EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH SIXTY … · 2011. 3. 21. · lepton-pair production in...

CERN LIBRARIES, GENEVA

CM-P00081677

CERN/1346 7 December 1979

ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE

CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

SIXTY-FOURTH SESSION OF THE COUNCIL

SOIXANTE-QUATRIEME SESSION DU CONSEIL

Geneva - 19 and 20 December 1979

PROGRESS REPORTS PRESENTED TO COUNCIL

BY THE DIRECTORS-GENERAL

RAPPORTS D'ACTIVITE PRESENTES AU CONSEIL

PAR LES DIRECTEURS GENERAUX

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INDEX

TABLE DES MATIERES

I. Page

I. RESEARCH DIVISIONS 1 I.

Theoretical Physics Division (TH) (J. Prentki)

3

I.

Experimental Physics Division (EP) (E. Gabathuler)

23

I.

Experimental Physics Facilities Division (EF) (A. Minten)

65

I.

Data Handling Division (DD) (P. Zanella)

85

II. ACCELERATOR DIVISIONS 97 II.

Proton Synchrotron Division (PS) (G.L. Munday)

99

II.

Intersecting Storage Rings Division (ISR) (F. Ferger)

117

II.

SPS Division (G. Brianti)

137

III. COMMON SERVICES DIVISIONS 155 III.

Division des Services techniques et Bâtiments (SB) (H. Laporte)

157

III.

Division des Finances (FI) (C. Tièche)

167

III.

Personnel Division (PE) (G. Ullmann)

175

III.

Health and Safety Division (HS) (A.J. Herz)

191

IV. SERVICES OF THE DIRECTORS-GENERAL 201

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I. RESEARCH DIVISIONS

- Theoretical Physics Division - Experimental Physics Division - Experimental Physics Facilities Division - Data Handling Division

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THEORETICAL PHYSICS DIVISION

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THEORETICAL PHYSICS DIVISION

The Division has continued its tradition of studying a wide range of problems, both phenomenological and more theoretical, on strong, weak and electromagnetic interactions as well as recent attempts to unify them. Most of the studies made have been at least guided by modern gauge theories and the fundamental interactions.

QCD has continued to be an important topic of current research, and there has been considerable work on both the phenomenological and theoretical properties of the theory. QCD perturbation theory has suggested a jet calculus of outgoing hadrons in reactions involving large momentum transfers. Leading order predictions for neutrino-induced jets have been investigated, with the conclusion that this aspect of QCD may be tested at present energies. Much attention has been paid to predictions for the energy flow into calorimetric detectors in e+e-annihilation, high pT hadron and photon reactions. The e+e- predictions have been verified at DESY, and underlie the recent claims to the discovery of the gluon. Predictions made for the photoproduction of high pT hadrons and photons, as well as for heavy quark pair production, can be tested soon using the SPS photon beam.

Several processes have been theoretically beyond the lowest orders of QCD perturbation theory. The results are very intriguing and can be summarized as follows: the newly computed corrections tend to be large, casting doubts on the phenomenological reliability of the lowest order predictions at present momenta. Examples of this dilemma occur in the comparison of deep inelastic structure functions with lepton-pair production in hadronic collisions, the breakdown of factorization in the neutrino production of hadrons, and in corrections to the hadronic widths of heavy quark-antiquark bound states. Recent SPS experiments suggest that the lowest order relations between lepton-pair production and deep inelastic data are indeed not applicable, and agree with the qualitative features expected from higher order QCD calculations. The calculation of the first higher order corrections to the moments of deep inelastic structure functions has been completed. Unambiguous comparisons of QCD and leptoproduction data have been attempted, with the conclusion that present experiments are not precise enough to test the theory beyond leading order, while agreeing qualitatively with the leading order predictions.

Meanwhile, QCD predictions have been made in areas where perturbation theory was previously thought not to be consistently applicable; small transverse momenta within very high energy jets, heavy quark multiplicities at high energies and the asymptotic behaviour

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of elastic form factors. The role of the ill-understood non-perturbative confining properties of QCD has been cornered into a smaller volume of phase space by the proof that QCD perturbation theory "preconfines" quarks by yielding colour-singlet pairs of small invariant masses. Further attempts have been made to develop experimental tests of the existence of the characteristic three-gluon couplings of QCD.

Work on non-perturbative phenomena in QCD has included studies of instanton effects at large momenta and of the U(1) problem. A simple effective Lagrangian dealing with the U(1) problem in the 1/N limit has been developed, and CP violation effects due to the QCD vacuum angle have been computed, including the leading contribution to the neutron electric dipole moment.

Turning to work on strongly interacting bound states, there have been studies of duality with non-relativistic potentials showing that a Q2 average over resonances removes the dependence on the confining part of the potential. A number of exact results on non-relativistic quarkonium potentials have been obtained, building on earlier work which had produced results on the order of levels, leptonic widths, and the reconstruction of the potential from experiment. Predictions for the T" leptonic width have been made, leading to an estimate of the total width which indicates that decays of this particle are Zweig-forbidden. The signs of some transition matrix elements have been shown to be potential independent. When combined with data from the J/ψ and Τ systems, the recent apparent observation at CERN of mesons with a single b quark leads to a test of the flavour independence of the potential. Inequalities on quark masses have been obtained, as well as predictions for the masses of yet-tobe-observed quark-anti-quark systems, some with non-zero net flavour. A prediction has been made for the energy gap between toponium and the threshold for the pair production of ( ) and ( ) mesons.

Interest in the spectroscopy of multiquark hadrons has been high because of its role as a unique testing ground for certain aspects of colour dynamics. If colour is indeed a hidden degree of freedom as now believed, then it should manifest itself in additional intricacies of the hadron spectrum, which are, however, accessible only in systems containing more quark constituents than the simplest and qqq. Previous investigations already suggest several effects sensitive to the details of colour dynamics and suitable for experimental study, e.g. the unusual properties of baryonia interpreted as diquark-antidi-quark colour molecules. Recent work reveals further interesting examples: the ΔΔ content of the deuteron arising from its component as a six-quark hadron bound by colour forces, and the effects of virtual quark-antiquark pair annihilation into one gluon, leading to large mass shifts and violations of the OZI rule in certain

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hadron states. Both of these should be clearly observable in experiments. More recently, the spectrum for Qc states (Q = u, d, s) has been investigated and the probable existence of narrow hadron states at around 3.5 GeV was noted. They can be copiously produced with the low-energy cooled antiproton devices now being planned at CERN, such as LEAR. This work on "traditional" hadron spectroscopy has been accompanied by a flurry of interest in "traditional" hadron collisions including the suggestion that the Pomeron intercept may be exactly 1 with a possible connection to the masslessness of QCD gluons, and parton and tunnelling interpretations of high-energy hadron-hadron collisions.

Proceeding to larger strongly interacting systems, there has been work on the problem of hot nuclear matter and its thermodynamics. One is led to expect three phases: a pure gas phase; a phase in which gas and "liquid" are in equilibrium; and a third phase which may best be described as a quark-gluon gas. There has been a growing awareness in nuclear physics in recent years that actual nuclei are very close to a phase transition associated with the pion field, and there have been studies of situations in which precursor phenomena to the phase transition become observable. One example may be the nuclear analogue of critical opalescence, which may even have been observed already. Of related interest is recent work on doubly radiative pion capture.

In parallel to this extensive activity on the strong interactions, there have been continued studies of weak and electromagnetic interactions and their possible combination with QCD into a grand unified theory. With regard to present experiments, analyses have been made of the significance of polarized deep inelastic electronhadron scattering and of the application of time reversal to unstable states used in experiments on parity violation in atoms. Calculations have been made of the bremsstrahlung production of vector mesons in e+e- collisions, as well as contributions to trilepton and like-sign dilepton cross-sections in neutrino collisions. Also, the electromagnetic radiative corrections to deep inelastic neutrino scattering have been re-analysed, and methods to implement them have been developed which are quark-mass and quark-model independent. Corrections to "sea" quark distributions and "longitudinal" cross-sections have been found to be enormous, and the corrections to scaling deviation tests have been fully studied. A proposed way of looking for heavy mesons containing the fifth b quark has led to the discovery at CERN of the first indications for the existence of ( ) and ( ) mesons. Estimates have been made for the unobserved mixing angles and masses of quarks. There have been several pieces of work on Higgs bosons. The production reactions Z° → Higgs + and e+e- → Higgs + have been analysed as possible ways for the proposed LEP machine to find light or heavy Higgs bosons. It has been suggested that the

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neighbourhood of 10 GeV may be a preferred range for the mass of the Higgs boson, and the resulting phenomenology explored. This and other work on Higgs boson production at LEP have been combined into a review written in collaboration with experimentalists from CERN and elsewhere, which concluded that LEP would have excellent chances of producing and detecting both charged and neutral Higgs bosons with masses up to about 100 GeV. A study has also been made of the possible production and detection at LEP of particles predicted by supersymmetry.

There has recently been an upsurge of interest in grand unified gauge theories of strong, weak and electromagnetic interactions, and now is perhaps an appropriate time to review progress in this domain and, in particular, recent contributions from the CERN Theoretical Physics Division. The first modern grand unified gauge theories were proposed in 1973 and 1974, around the time of the discovery of neutral currents but before the discovery of the J/ψ and charm. This was at a time when many physicists were still unconvinced that gauge theories constituted an appropriate framework for describing elementary particle interactions. Naively viewed, the simplest grand unified theories seem to predict values of the weak mixing angle θw which are larger than those found by experiment, and also yield mass relations between quarks and leptons which look rather unrealistic. However, it was soon realized that the weak mixing angle is renormalized downwards by calculable symmetry breaking effects, and more recent refined calculations at CERN and elsewhere have yielded values of θw which are quite close to the latest experimental values. It was also realized that the quark to lepton mass ratios acquired large calculable corrections, and shown that the μ and Τ lepton masses could be used to make successful calculations of the strange and bottom quark masses. These predictions turned out to be sensitive to the total number of quarks, and to favour the existence of six or at most eight quarks. Motivated by these successful predictions of grand unified theories, considerable effort has been devoted to estimating the proton lifetime, which is generally finite in grand unified theories, because they contain baryon number-violating forces which transform quarks into leptons. The latest calculations suggest that the proton lifetime may be only slightly longer than the present experimental lower limit. This has motivated several proposals for new experiments to search for proton decay, and CERN theorists have been active in discussions with interested experimentalists.

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Despite these successes and hopes for grand unified theories, a number of important problems remain which may indicate that present approaches are fundamentally inadequate, and there has been a lot of work on these problems in the Theoretical Physics Division in the past year. One such problem is that of the mass scales in grand unified theories, which are usually generated by spontaneous symmetry breaking through explicit Higgs fields. The possible directions of spontaneous symmetry breaking in SU(n) gauge theories have been clarified, and specific Higgs potentials have been constructed which are capable of yielding the desired pattern of symmetry breaking in the simplest SU(5) gauge model. The main outstanding problems concern the scales of different stages of symmetry breaking, and the large ratios between them. It has been shown that the largest grand unification symmetry breaking scale may be as high as the Planck mass of 1019 GeV, though it seems more natural to suppose the scale to be four or five orders of magnitude smaller, particularly if symmetry breaking comes about through radiative corrections. It remains to be understood why the usual weak interaction scale is 12 or 13 orders of magnitude smaller still. Discrete symmetries have been shown not to help, and while such a large hierarchy of scales is possible if symmetry breaking arises from radiative corrections, it has nevertheless been shown to require an arbitrary and unnatural adjustment of a parameter. However, if such a large hierarchy can be achieved, it seems quite possible that the mass of the single Higgs boson expected in the Weinberg-Salam model may be about 10 GeV. In this case its phenomenology reveals unusual feature, and it may be detected in the relatively near future.

The construction of grand unified theories has also been shown to give useful upper bounds on the possible masses of Higgs bosons, as well as on fermion masses. A long standing problem for the simplest grand unified theories has been the spectrum of light quark and lepton masses. A speculation has recently been made that this problem may be resolved without altering fundamentally the structure and phenomenology of such theories, including the predicted nucleon decays.

An exciting development in grand unified theories has been a growing connection with cosmology, and the early stages of the big bang in particular. It has been argued that a CP and C violating component in the baryon number violating interactions may have generated a net quark-antiquark asymmetry which has subsequently become the global excess of matter over antimatter seen in the universe at the present epoch. Grand unified theories may be used to discuss other aspects of the evolution of the very early universe. For example, there was probably an early period when all known elementary particle

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interactions were not in perfect thermal equilibrium, which may have played an important role in the suppression of primordial irregularities. It is possible that the inhomogeneities which eventually evolved into galaxies may have originated around the time of the breakdown of the grand unification symmetry.

Present theories of grand unification do not include gravitation or supersymmetry, and supersymmetry and supergravity have continued to be the object of intensive research. One of the most interesting properties of supersymmetric theories is the compensation of the vacuum self energy between bosons and fermions, to all orders in perturbation theory, a fact which could be related to the vanishing of the cosmological constant in the real world. This compensation is a consequence of the supersymmetry algebra, and it turns out that for spin 0 and 1/2 fields, supersymmetric Lagrangians can be characterized as those for which the compensation occurs. When supersymmetry is spontaneously broken, the vacuum self energy does not vanish, but is less divergent than in an arbitrary field theory, as a consequence of sum rules satisfied by the masses of bosons and fermions. The radiative corrections to these sum rules have been studied. In spontaneously broken supergravity, the mass sum rules are especially strong and the vacuum energy is finite to one-loop. The group-theoretic origin of these sum rules has recently been clarified. Other developments have been of a more technical nature. With the aim of understanding the mathematical structure of supergravity theories, non-linear supersymmetric σ models have been studied and the relation between complex structure and supersymmetry has been demonstrated. The description of scalar fields in terms of antisymmetric tensor fields with gauge invariance, natural in supergravity theories, has been investigated.

Other more mathematical problems studied by members of the Division have included topological aspects of gauge theories. There has been work on multi-monopole configurations, and a perturbative expansion incorporating both long and short range effects has been obtained. Important in the analysis of gauge theories such as QCD are stationary points in the functional integral, and in some cases virtual saddle points. The applications of semiclassical approximation methods, which involve the computation of quantum fluctuations, require the use of mathematical techniques from differential geometry such as fibre bundles, connections, the index theorem, and complex analysis. Further applications of the index theorem to the axial anomaly have been described, as well as some uses of the holonomy group. The Seeley coefficients of operators governing quantum fluctuations around Yang-Mills instantons have been studied. Two-dimensional models have proved a useful laboratory for studying phenomena associated with instantons, and quantum fluctuations in CPN-1 models, the stability of solutions to non-linear σ models,

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and their embeddings in CPN-1 models have all been investigated. Work has been done on the transformation of gauge theory path integrals from phase space to configuration space. Studies have been made of scattering by stationary external metrics, Yang-Mills potentials and general non-confining potentials. In the latter case, it has been shown that a potential which oscillates sufficiently rapidly can simulate short-range potentials in many respects. Also, new conditions for the finiteness of total cross-sections for slowly decreasing potentials have been obtained.

In addition to their theoretical work, members of the Division have been active in discussions with experimentalists, particularly in the areas of deep inelastic and hard scattering experiments, nuclear phenomena, weak interactions and tests of grand unified theories. Members of the Division have also been active on committees reviewing experiments with the different CERN accelerators, and in studies of future projects. These have included the low-energy LEAR project, antiprotons in the ISR, the SPS collider, a possible European ep colliding ring facility, the LEP project, and a possible eventual world accelerator. Members of the Division have also been active teaching at summer schools. An attempt has been made at presenting QCD in a serious but light-hearted theatrical manner, as well as using the more traditional and formal methods of lecturing.

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LIST OF REPORTS - December 1978 - November 1979

R. Bertlmann, H. Grosse and A. Martin

The lepton width of the Y".

A.R. White Critical and super-critical Reggeon field theory.

A. De Rujula, R. Petronzio and A. Savoy-Navarro

Radiative corrections to high-energy neutrino scattering.

F.E. Close Structure functions and the quark-parton model.

J. Ellis, M.K. Gaillard and V. Zakrzewski

Non-perturbative effects on factorization in high-momentum processes.

J. Ellis, M.K. Gaillard and D.V. Nanopoulos

Baryon number generation in grand unified models.

P.E. Close The new particles and their significance.

H. Grosse, H. Narnhofer and W. Thirring

Accurate determination of the scattering length for the scattering of e- on μ atoms.

G.J. Gounaris Current propagator : duality between vector mesons and perturbative QCD.

G. Preparata Predictions for the top-quark mass and for the generalized Cabibbo angles.

G.P. Chew Bootstrap theory of quarks.

P. Zachariasen The infra-red behaviour of the running coupling constant in Yang-Mills theories.

W. Nahm A critique of astrophysical applications of Hagedorn's bootstrap.

G. Parisi and R. Petronzio Gluon fragmentation functions from quark jets.

B. Schrempp and P. Schrempp Strong interactions - A tunnelling phenomenon ? - II. Inclusive particle production at small and large pT.

R. Hagedorn, I. Montvay and J. Rafelski

Thermodynamics of nuclear matter from statistical bootstrap model.

B. de Wit and S. Ferrara On higher-order invariants in extended supergravity.

H. Fritzsch Polarized electron-hadron scattering and weak interaction theory.

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V. Cerny Charmed quark fragmentation functions in a Monte Carlo quark recombination model.

Ph. Combe, A. Sciarrino and P. Sorba

On the directions of spontaneous symmetry breaking in SU(n) gauge theories.

A.M. Din, J. Finjord and W. Zakrzewski

Mass corrections to some instanton effects.

P. Binétruy and G. Girardi Jets in neutrino deep inelastic scattering.

M. Daniel Some uses of the holoncmy group.

G. Curci and E. Ferrari Answer to a criticism by Ojima on : "An alternative approach to the proof of unitarity for gauge theory".

O. Brander A peculiar property of the wave functions for confining potentials.

S.N. Sokolov Classical analogues of the Møller operators of the Pearson example, and of the Birmann-Kato invariance principle.

V.N. Popov and T.T. Wu Infra-red asymptotic behaviour of one-fermion Green's function in a scalar model with isospin.

O. Haan and K.H. Mutter A new perturbative approach for the anharmonic oscillator.

P. Binétruy and G. Girardi Improved Sterman-Weinberg jet formula.

G.F. Chew Topological colour and disc mating; unitarity as the source of zero triality.

K. Harada, T. Kaneko and N. Sakai

Hadronic lepton-pair production beyond the leading order in perturbative QCD.

D. Amati and G. Veneziano Preconfinement as a property of perturbative QCD.

J. Baacke On the divergence of parton distributions for static bags.

R. Barbieri, G. Curci, E. d'Emilio and E. Remiddi

Strong radiative corrections to annihilations of quarkonia in QCD.

J. Stern Interference of particles emitted from a sphere.

H. Römer Axial anomaly and boundary terms for general spinor fields.

W. Furmanski, R. Petronzio and S. Pokorski

Heavy flavour multiplicities at very high energies.

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I.I.Y. Bigi Angular energy flow beyond lowest order.

G. Parisi and R. Petronzio Small transverse momentum distributions in hard processes.

L. Van Hove The quark recombination mechanism in multi-hadron production.

A.R. White The confinement of massless non-Abelian gluons and rising total cross-sections.

P. Lambert Explicit solutions of the Korteweg-de Vries equation without scattering data.

Y. Frishman and A.R. White Contribution of renormalon singularities.

G. Curci, M. Greco and Y. Srivastava

QCD jets from coherent states.

H. Satz Dimensionality in the statistical bootstrap model.

J. Ellis, M.K. Gaillard, D.V. Nanopoulos and G.T. Sachrajda

Is the mass of the Higgs boson about 10 GeV ?

G.P. Chew, B. Nicolescu., J. Uschersohn and R. Vinh Mau

Topological quark-gluon structure of elementary hadrons beyond mesons and baryons.

J.S. Bell and J. Pasupathy On duality between resonances and free quark-antiquark pairs.

J. Baacke Field theoretic bags : some formal considerations.

E. Christova and S.T. Petcov Model-independent analysis of the weak interaction in e- - Ν elastic scattering experiments.

B. Humpert Asymptotic freedom versus exact lowest order QCD.

H. Fritzsch Quark masses and flavour mixing.

N. Sakai Factorization breaking in deep inelastic neutrino hadron production in perturbative QCD.

W. Nahm Interacting monopoles.

S.D. Viollier Elastic alpha-nucleus scattering at more than 300 MeV/n.

L. Gonzales-Mestres and P. Aurenche

Glueball-Pomeron identity and the transverse structure of two-jet events.

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M. Fierz The scientific work of Albert Einstein.

A.M. Din, P. Di Vecchia and W.J. Zakrzewski

Quantum fluctuations in the one-instanton sector of the CPn-1 model.

Tu Tung-Sheng and Wu Chi-Min QCD predictions for γΡ collisions with a large pT real photon in the final state.

H. Fritzsch Comment about the magnetic moments of the hyperons.

H. Fritzsch How to discover the Β mesons.

J.S. Bell and J. Pasupathy JWKB connections for radial wave functions, and bound-state/free-state duality.

D. Amati The structure of hard processes from QCD.

G. Veneziano U(1) without instantons.

J. Kalinowski, S. Pokorski and L. Van Hove

Probabilistic quark-model approach to proton fragmentation.

M. Magg Stable Yang-Mills fields for an over-critical point source.

B. Humpert and W.L. van Neerren Ambiguities in the infra-red regularization.

K. Chadan and A. Martin Scattering theory and dispersion relations for a class of long-range oscillating potentials.

J. Dias de Deus Parton distributions in baryons and mesons consistent with the naïve quark model and QCD.

J. Smith Trimuon production by antineutrinos.

R.M. Godbole and J. Smith The production of neutral vector mesons by bremsstrahlung in electron-positron colliding beams.

J. Rafelski and R. Hagedorn Thermodynamics of hot nuclear matter in the statistical bootstrap model.

P. Christillin, M. Rosa-Clot and S. Servadio

Muon wave function and Coulomb propagator in radiative muon capture in nuclei.

W.J. Zakrzewaki Some instanton effects at large momenta.

D.R.T. Jones and S.T. Petcov Heavy Higgs bosons at LEP.

A. Martin Boundedness of total cross-sections in potential scattering.

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J. Finjord A light Higgs boson : the decay zo → Ko l+l-.

W. Furmanski e+e- jets : cones or tubes ?

W. Furmanski and S. Pokorski Sensitive tests of QCD in large pT calorimeter measurements.

J. Smith and C.H. Albright Like-sign dimuon production by neutrinos and antineutrinos.

Q. Shafi and C. Wetterich Gauge hierarchies and the unification scale mass.

H. Hogaasen, P. Sorba and R. Viollier.

Hidden colour and the isobar content of the deuteron.

J. Smith Trilepton production by neutrinos and antineutrinos.

P. Castorina, G. Nardulli and G. Preparata

A realistic description of deep inelastic structure functions.

G.F. Chew Hadron-disc spectrum of the spherical S matrix.

H. Fritzsch Flavour mixing and quark masses in sequential flavourdynamics.

J. Rafelski and R.D. Viollier Test of QCD with heavy quark bound states.

H. Grosse and A. Martin Exact results on potential models for quarkonium systems.

Chang Chao-hsi, Tu Tung-sheng and Wu Chi-min

QCD predictions for γ-p collisions with a large pT real photon in the final state (II).

J. Dias de Deus and W.A. Rodrigues, Jr.

Centauro, Geminion and multi-pion events.

J.S. Bell and R.A. Bertlmann Testing Q2 duality with non-relativistic potentials.

J. Lukierski Four-dimensional quaternionic σ models and SU(2) gauge fields.

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J. Rafelski Hydrogenic mesomolecules and muon catalyzed fusion.

P. Di Vecchia An effective Lagrangian with no U(1) problem in CP n - 1 models and QCD.

H.M. Chan Baryonium-nuclear atom or colour molecule ?

J. Ellis Are weak interactions solved ?

D. Ebert Unified gauge model with a non-linear chiral SU(4)×SU(4) hadron Lagrangian.

I.I.Y. Bigi The decay of heavy quarkonia states and the triple gluon vertex.

G. Alberi, G. Baldracchini and V. Roberto

Role of the quark parton model in deuteron inelastic screening at T ≠ 0.

N. Cabibbo, L. Maiani. G. Parisi and R. Petronzio

Bounds on the fermions and Higgs boson masses in grand unified theories.

A. Martin The sign of the electric dipole matrix element 2S → 1P.

W. Furmanski and S. Pokorski Exact solution of the Q2 evolution equations in QCD.

F. Schwarz An approximation scheme for constructing πOπO amplitudes from ACU requirements.

A.R. White Why rising cross-sections are further evidence for a non-Abelian gauge theory of strong interactions.

T.S Tu Is it possible to measure QCD Compton effects ?

G. Veneziano Momentum and colour structure of jets in QCD.

G. Fäldt The pion mass difference in threshold pion reactions on light nuclei

G. Fäldt Threshold πO photoproduction on deuterium.

P. Christillin and T. Ericson Theory of doubly radiative π capture in nuclei.

J. Dias de Deus and N. Sakai Generating quark and gluon fragmentation functions from QCD.

H.M. Chan Theoretical implications of narrow hadron states.

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J. Ellis, M.K. Gaillard, A. Peterman and C. Sachrajda

A hierarchy of gauge hierarchies.

P. Christillin, M. Rosa-Clot and S. Servadio

Radiative muon capture in medium heavy nuclei.

R. Schrader High-energy behaviour for non-relativistic scattering by stationary external metrics and Yang-Mills potentials.

H. Fritzsch Masses and mass generation in chromo and flavour dynamics.

M. Jacob High pT and jets.

J. Ellis Status of gauge theories.

A. Para and C.T. Sachrajda Search for the effects of higher-order terms in deep inelastic lepton-hadron scattering.

H. Fritzsch Seeing the Β mesons in hadronic collisions.

W. Furmanski and S. Pokorski QCD tests : 3G vertex effects.

S. Ferrara and B. Zumino The mass matrix of N = 8 supergravity.

G. Fäldt and I. Ericson Binding effects in coherent πO photo-production on deuterium.

I.I.Y. Bigi Experimental tests for the equality of gluon-gluon and quark-gluon coupling on resonance in e+e- annihilation.

E.K. Manesis and N.A. Papadopoulos

QCD and angular energy patterns in leptoproduction.

F. Niedermayer Colour distribution in hadron-hadron scattering.

C.N. Yang Einstein and his impact on the physics of the second half of the Twentieth Century.

A.P. Balachandran, G. Marmo, B.S. Skagerstam and A. Stern

Supersymmetric point particles and monopoles with no strings.

G. Preparata and J. Soffer An important test of short-distance behaviour : the spin dependence of large angle nucleon-nucleon elastic scattering.

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G. Preparata QGD : problems and alternatives.

M. Magg, Q. Shafi and C. Wetterich

Gauge hierarchy in presence of discrete symmetry.

J. Bernabeu and P. Pascual Neutral current couplings of higher generations.

L. Michel Minimal of Higgs-Landau polynomials.

L. Girardello and J. Iliopoulos Quantum corrections to a mass formula in broken supersymmetry.

J. Bernabeu and P. Pascual Long-range parity violating : interaction in muonic atoms.

L. Bergström and S. Fredriksson Backward production on nuclei and the tube model.

S. Fredriksson The collective tube model - and how to disprove it.

A.M. Din and W.J. Zakrzewski Stability properties of classical solutions to non-linear σ models.

A.M. Din and W.J. Zakrzewski Embeddings of classical solutions of O(2p+1) non-linear σ models in CPn-1 models.

J. Ellis SU(5). E. Witten Dyons of charge eθ/2π.

C.N. Yang Fibre bundles and the physics of the magnetic monopole.

N. Cabibbo and 1. Maiani Multilepton configurations in b and t decays.

Ρ.ΙΫ. Townsend Covariant quantization of antisymmetric tensor gauge fields.

A. Gonzales-Arroyo, C. Lopez and P.J. Yndurain

Testing QGD predictions beyond the leading order fo non-singlet structure functions in neutrino scattering.

M. Magg and Q. Shafi Symmetry breaking patterns in SU(5). J.D. Jackson Gharmonium chi states : radiative and

hadronic widths, spin of the gluon.

S.J. Brodsky, Y. irishman, G.P. Lepage and C. Sachrajda

Hadronic wave functions at short distances and the operator product expansion.

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V.F. Weisskopf Personal impressions of recent trends in particle physics.

B. Zumino Supersymmetry and Kähler manifolds.

A. Gonzales-Arroyo and C. Lopez Second order contributions to the structure functions in deep inelastic scattering. III The singlet case.

R.J. Crewther, P. Di Vecchia, G. Veneziano and E. Witten

Chiral estimate of the electric dipole moment of the neutron in quantum chromo-dynamics.

C.H. Chang Tests of QCD for three-jet semi-leptonic processes based on generalized moments.

D.V. Nanopoulos Bounds on the baryon/photon ratio due to our existence.

C.T. Sachrajda Applications of perturbative QGD to hard scattering processes.

B. Humpert and W.L. Van Neerven How to regularize the infra-red and mass singluarities in QCD.

A. De Rujulá Quantum chromodynamite.

A.P. Balachandran, G. Marmo B.S. Skagerstam and A. Stern

Spinning particles in general relativity.

A. Martin Flavour independence of forces between quarks.

J. Finjord, G. Girardi and P. Sorba

The needle in the large pT haystack : Higgs versus quark or gluon jets together with ZO in hadronic reactions.

R. Tarrach The two-body hadronic Δo decays are fine.

J. Ellis Status of perturbative QGD.

J. Ellis and G. Steigman Non-equilibrium in the very early universe.

J. Ellis and M.E. Gaillard Fermion masses and Higgs representations in SU(5).

T.S. Tu, H.C. Yin and T.N. Yuan General form of effective Lagrangian in path integral quantization formalism.

J.S. Bell Reversal in time, unstable states, and parity violation in atoms.

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M. Jacob New directions in elementary particle physics - from very low to very high energies.


On the effective Lagrangian for baryon decay.

P. Lambert Padé approximants and closed form solutions of the XdV and MKdV equations.

C.M. Wu A possibility for measuring the S,P,T type neutral weak current in muon scattering.

T.S. Tu Photoproduction of charm and beauty.

P.K. Townsend Local supersymmetry without gravity ?

A.K. Common and A. Martin Constraints on the decay rates of quarkonium.

C.H. Chang Hadronic production of J/ψ associated with a gluon.

R. Casalbuoni, V. Eittenberg and S. Yankielowicz

Self-duality conditions for spin systems defined on a new class of non-Abelian solvable finite groups.

A. Peterman Towards the early stages of the universe.

H. Nicolai On a new characterization of scalar supersymmetric theories.

M. Daniel The operators governing quantum fluctuations of Yang-Mills multi-instantons on S4 and their Seeley coefficients.

J. Rafelski annihilation on heavy nuclei.

H. Fritzsch The unification of physics.

A. Peres The physicist's role in physical laws.

T.S. Tu QCD predictions for beauty production in πp and collisions.

A. Martin Boundedness of total cross-sections in potential scattering II.

A. Molinari Photon-induced nuclear processes.

I. Ragnarsson Some applications of the shell correction method.

I. Ragnarsson The shell correction method and its applications to nuclear masses.

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I.I.Y. Bigi Are Cabibbo suppressed decays really suppressed in D+ decays ?

P. Aurenche and J. Lindfors Direct photon production beyond leading order in QCD.

C.M. Wu QCD predictions for the Q2 dependence of quark and gluon fragmentation functions using Altarelli-Parisi type equations.

C.M. Wu QCD predictions for the distribution functions of the photon using Altarelli-Parisi type equations

M. Daniel, G. Lazarides and Q. Shafi

Electric and magnetic flux in unified SU(5) gauge theory.

R.A. Bertlmann and A. Martin Inequalities on heavy quark systems.

P. Castorina, G. Nardulli and G. Preparata

Understanding deep inelastic scattering data.


The smoothness of the Universe.

I.I.Y. Bigi and M. Fukugita A clean test of the W boson exchange model for the decays of charm and bottom mesons.

R. Barbieri, D.V. Nanopoulos G. Morchio and P. Strocchi

Neutrino masses in grand unified theories.

G. Lazarides Mass generation in the O(3) non-linear σ model.

A. De Rùjula, J. Ellis, R. Petronzio, G. Preparata and W. Scott

Can one tell QCD from a hole in the ground ?

E.J. Weinberg Fundamental monopoles and multi-monopole solutions for arbitrary simple gauge groups.

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EXPERIMENTAL PHYSICS DIVISION

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EXPERIMENTAL PHYSICS DIVISION

1. SPS PROGRAMME

1.1 Physics from hadrons beams

1.1.1 Lepton pair production

The SISI Collaboration,WA11, have measured 500 μ+μ- pairs with masses ≥ 3.8 GeV produced by π- Be collisions at 150 and 175 GeV/c. They find the production cross section is about three times that predicted by the Drell-Yan process where in this calculation they use the nucleon structure functions derived from deep inelastic lepton scattering. They derive the pion structure function Fπ(x) ~ √x(1 - x)b with b = 1.56 ± 0.18. The CEN Saclay-CERN-Collège de France-E.P. Palaiseau-Orsay Collaboration, NA3, have measured μ+μ- pair production with π±, Κ± and p± beams of 200 GeV/c and a π- beam of 280 GeV/c and have ~ 15 000 events with (μ+μ-) mass > 4 GeV. For each beam they find the experimental cross section is greater than that predicted using the Drell-Yan mechanism using the CDHS values of the nucleon structure functions, the factor being about 2.2 times. The shape of the pion structure function is found to be Fπ(x) ~ x0.4±0.1(1 - x)0·9±0·1.

The discrepancy between the absolute cross sections from deep inelastic neutrino scattering and from muon pair production is interpreted as being caused by QCD effects, i.e. the necessity to include diagrams involving gluons. These results suggest that the QCD corrections are large.

Both experiments find their results are consistent with scaling, i.e. M3.dσ/dM is a function only of M2/s.

By using both a hydrogen and a platinium target, the NA3 experiment find that cross section has a dependence on the target Atomic Number A of A 1 . 0 3 ± 0 . 0 4. They also find that the charge asymmetry and decay angular distributions are in agreement with the predictions of the Drell-Yan mechanism.

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Upsilon γ, production by pions has been observed for the first time by NA3. The cross section is found to be 30 times higher than that by incident protons and to be 2×10-4 of the cross section for J/ψ production.

The Birmingham-CERN-Palaiseau (E.P.) Collaboration, WA39, have measured (μ+μ-) pairs produced by 40 GeV/c beams of π+, Κ± nd p± For J/ψ production, the following cross section ratios are observed:

π+/π = 1.02 ± 0.14, K +/K - = 0.44 ± 0.09, Κ-/π- = 0.92 ± 0.10

= 1.10 ± 0.10, = 5.2 ± 1.2.

An analysis of the Feynman x-distributions using the quark fusion model requires roughly equal contributions from valence quarks and charmed sea quarks. The implied couplings are compatible with the observed cross section ratios. Data have also heen taken in hydrogen.

The NA3 Collaboration find for J/ψ production the cross section ratios

π+/π- = 1.003 ± 0.004 for platinium and 0.987 ± 0.02 for a hydrogen target. For upsilon production on a platinium target the following ratios are found:

Κ+/π+ = 0.34 ± 0.23, p/π+ = 0.03 ± 0.02, π-/π+ = 0.76 ± 0.29.

These are consistent with a quark fusion model which would give 0.10, 0.05 and 0.83 respectively. On the other hand a gluon fusion model would give Κ+/π+ = 1.

The Pàlaiseau (Ε.P.-Strasbourg-Zurich (ΕΤΗ) Collaboration, NA10, are preparing a beam dump experiment to measure with high resolution and large acceptance the inclusive production of massive muon pairs by the pion beam of high intensity (up to 1010 π/pulse) which is being constructed in the new experimental hall EHN3.

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1.1.2 Single lepton production

The Bologna-Glasgow-Rutherford-Saclay-Torino Collaboration, WA30, have studied prompt electron production in 70 GeV/c π- interactions on hydrogen in the Track Sensitive Target (TST) in BEBC. Preliminary results on 5100 interactions are that, after cuts, five prompt electrons (3 e+ and 2 e-) are observed while the calculated background is 0.7 ± 0.4 events. This would give a prompt e/π ratio of (3.8 ± 2.0)10 and using standard assumptions, a π- p → cross section of 23 ± 12 μb.

The Brussels (IIHE)-Helsinki-Liverpool-Mons-Stockholm Collaboration, WA31, are analysing the interactions of 70 GeV/c antiprotons in the TST and have found several single e± candidates in a subsample of 20 000 interactions.

Results on prompt neutrino production are given as the Beam Dump results in sect. 1.2.13.

1.1.3 Resonances - beauty, strangeonium, baryonium, charmonium and others

The Saclay (CEN)-London (IC)-Southampton-Indiana Collaboration, SISI, WA11, have possibly observed a new mesonic resonance with a mass of 5.3 GeV. The great interest in this is that the decay mode (J/ψ)Κπ suggests that it could be a meson containing a b-quark. In view of the importance of direct observation of beauty, additional running time has been allocated to WA11. Preliminary results with 75% more data tend to confirm the resonance whose significance is now at the level of 4.1 standard deviations. The experiment was performed with 150 and 175 GeV/c π- beams on a Be target in a large-acceptance spectrometer which was triggered by J/ψ → μ+μ-.

Surprisingly little is known about the strangeonium ( ) system, but several experiments are being performed to remedy this. The Amsterdam-CERN-Cracow-Munich-Oxford-Rutherford Collaboration, WA3, have observed in the reaction π-p → Κ+Κ- n at 63 GeV/c a peak in the (Κ+Κ-) mass distribution at 2300 ± 10 MeV and width Γ = 272 ± 32 MeV. The resonance is found to have the quantum numbers JP = 5-, C = -1 and very probably IG = 1+. It may be speculated that it is the highest member of the series p, f/A2, g, h with JP = 1-, 2+, 3- and 4+ respectively.

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Phi-production is studied in seven experiments. The ACCMOR Collaboration, WA3, show that when a Φ-meson is produced, there is a higher rate of production of a strange meson or of a second Φ-meson - this is a striking confirmation of the Okubo-Zweig-Iizuki rule. This collaboration, using π±, Κ±, p± beams of 63 and 93 GeV/c, the CEN, Saclay-CERN-Collège de France-E.P. Palaiseau-Orsay Collaboration, NA3,with similar beams of 200 GeV/c and the Aachen-Berlin-Bonn-CERN-Cracow-Heidelberg-Innsbruck-London (IC)-Vienna-Warsaw Collaboration with Κ- and π+ beams of 16 GeV/c show that Φ-production is more frequent with kaon beams than with π or p beams. The ABBCCHILVW Collaboration also show there is a strong forward peak of Φ-production by kaons, which may be attributed to the effect of the strange valence quark contained in the kaon. The WA3 Collaboration find the production data consistent with the quark fusion model. The Glasgow-Birmingham-CERN Collaboration, WA48, using 13 GeV/c K+ are studying the (Κ+Κ-) state and expect to obtain over 100 000 phi-mesons. Phi-production

has been studied at ISR energies by the Amsterdam-Louvain-Northwestern Collaboration, R607, and by the CERN-Collège de France-Heidelberg-Karlsruhe Collaboration, R410.

Strange-baryonium is being studied by the Geneva-Lausanne Collaboration, WA10, in the reactions K+p → ()p and Κ-p → ()p at 50 GeV. An amplitude analysis of the moments of ( ) and ( ) decay angular distributions gives evidence for two broad states with spin-parity 2- and 4- at 2.3 and 2.5 GeV respectively. WA48 is also studying ( ) production in Κ+p reactions at 13 GeV/c. Further the Bari-Birmingham-CERN-Milan-Paris (Univ. VI)-Pavia Collaboration, WA60, are taking data with Omega Prime Spectrometer with Κ- and π- beams of 18.5 GeV/c to search for Strangeonium and Baryonium. The ACCMOR Collaboration, WA3, observe the production of the resonance at 1940 GeV in the reaction pp → + anything, at 93 GeV. The CERN-Liverpool Collaboration, WA49, using a 12 GeV/c beam find no peaks in ( ) system at 2.02 and 2.20 GeV in the reaction → , but observe small (two standard deviations) signals in the reaction → π+π-. This question is also being studied by the CERN-Neuchâtel-Palaiseau

(E.P.)-Paris (Collège de France) Collaboration, WA56, using a 20 GeV/c π+ beam in the Omega Prime spectrometer.

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The SISI Collaboration, Wall, have measured gamma rays as well as μ+μ- pairs and find evidence for the cascade decay χ(3515) → (J/ψ)γ. The Amsterdam-Bristol-CERN-Cracow-Munich-Rutherford Collaboration, NAll,will measure D-meson production in π- Be interactions at 200 GeV at the end of 1979.

The IHEP-IISN-LAPP Collaboration, NA12, are well advanced in their preparations to measure neutral final states in the reaction π-p → M0 + n at 40 GeV.

1.1.4 Photoproduction experiments

The Bonn-CERN-Glasgow-Lancaster-Manchester-Orsay-Palaiseau (EP)-Paris VI-Rutherford-Sheffield Collaboration, WA4, are analysing photo-production data taken with the Omega spectrometer. A sample of 14 000 η mesons is obtained by observation of η → 2γ decays. Evidence for F-meson production is seen at the 4-standard deviation level in both the (η3π) and (η5π) decay modes, the corresponding F-masses being 2.017 ± 0.011 and 2.020 ± 0.007 MeV. Indications of the decay into Κ0π+π- and Κ+π- have been found at the 3.5 standard deviation level. Prompt electron production has been observed and a total charm production cross section of 800 ± 200 nb has been calculated. Evidence is also found for higher mass resonances. Peaks are observed at 1.6 GeV in both the 4π channel (mainly from ρππ) and 2π channel with widths of 0.5 and 0.23 ± 0.08 GeV respectively. The different widths may be caused by the complicated nature of the non-resonant background. In the (π+π-π0) mass spectrum significant peaks are found at the Φ-mass and at 1.27 and 1.67 GeV each with an observed cross section of 100 nb. In the reaction γp → Κ+Κ- p, an enhancement is observed in the (Κ+Κ-) mass distribution at 1.76 ± 0.01 GeV with Γ = 120 ± 30 MeV.

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The Frascati-Milan-Pisa-Rome, FRAMM, Collaborateon, ΝΑ1, have set up a forward spectrometer for the detection of charged particles and photons as well as a vertex detector. The apparatus has been successfully tested and effective mass peaks have been observed at the π0, ρ and ω masses. A silicon live target has been developed to study lifetimes in the range 5×10-4 to 10-2 s. It consists of 30 detectors, each 300 μm thick, with spacing variable between 100 and 600 μm. The lifetime would be measured by the ionization pattern as a charmed particle decay would give an increase in the multiplicity.

The London (WC)-Southampton-Frascati-Milan-Pisa-Rome Collaboration, NA7, have constructed apparatus to be added to the Framm experiment, NA1, to measure the electromagnetic form factors of the π and Κ mesons. This apparatus has now been tested in the D31 beam of the P5 and works satisfactorily.

1.1.5 Charm production

Production of charmed particles is being studied in a number of experiments. Results with neutrino beams are given in sects 1.2.2 and 1.2.3 and ISR results are presented in sect. 2.1. Reports from WA11 and NA11 are given in sect. 1.1.3 and a silicon live target for NA1 is described in sect. 1.1.4.

The Bologna-CERN-Florence-Genova-Moscow (Lebedev)-Paris VI-Santander-Valencia Collaboration, WA45, exposed 15 litres of emulsion to a tagged photon beam from 80 GeV electrons in the Omega spectrometer. Most of the emulsion turned out to have manufacturing faults and only ~ 500 events could be added to the 500 events found in the test experiment. A neutral charmed particle was found decaying after 1227 ± 2.2 μm according to the scheme → Κ+π-π+π- where all the decay products were detected in the spectrometer. The mass was found to be 1866 ± 8 MeV and the decay time (2.26 ± 0.05)-10-14 s. This experiment will be continued soon as WA58 with an exposure of 30 litres of emulsion in the Omega Prime Spectrometer.

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To observe directly the decay of charmed particles, a high-resolution fast-cycling bubble chamber, (LEBC - Little European Bubble Chamber) has been constructed. It is 20 cm in diameter, has a volume of ~ 1 litre and a bright field optical system which has been found to give bubble images corresponding to 35-50 μm in space. The Brussels-CERN-Oxford-Padova-Rome-Rutherford-Trieste Collaboration, NA13, have taken some 110 000 triggered pictures in a 340 GeV/c π- beam. From the scanning of ~ 36 000 interactions 12 events were found where a pair of decays were observed. This would correspond to a visible pair production cross section of 7 to 10 μb. The Amsterdam-Brussels-CERN-Madrid-Mons-Nijmegen-Oxford-Padova-Paris-Rome-Rutherford-Serpukhov-Stockholm-Trieste-Vienna

Collaboration, NA16, will use an improved version of LEBC together with the downstream analysis system of the European Hybrid Spectrometer to study production and properties of charmed particles by beams of 370 GeV π- and 400 GeV protons.

1.1.6 Hyperon physics

The Bristol-Geneva-Heidelberg-Orsay-Rutherford-Strasbourg Collaboration, WA2 and WA46, have continued to run with the hyperon beam. From a sample of 2500 Ω- → ΛΚ- decays at Ω- momenta of 98.5 and 115 GeV/c, an Ω-

lifetime of (0.822 ± 0.028) × 10-10 s was found. The main Ω- decay branching ratios have been measured to be (68.3 ± 1.3)% to ΛΚ-, (23.4 ± 1.3)% to Ξ0π- and (8.0 ± 0.8)% into Ξ-π0. Further data with 15 000 decays, have been taken. Cross sections for the inclusive production by 200 and 210 GeV protons of π+, Κ+, p, Σ+, , , d and π-, Κ-, , , , Ω- and in the forward direction have been measured at lab momenta between 70 and 130 GeV/c. The differential cross sections have a (1 - x)n dependence where n is characteristic of the particle.

The Bristol-Geneva-Heidelberg-Orsay-Rutherford-Strasbourg Collaboration, WA42, have started taking data on the measurement of hyperon total cross sections using the hyperon beam.

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1.1.7 Exclusive reactions

The CERN-Annecy (LAPP)-Genova-Copenhagen-Oslo-London (UC) Collaboration, WA7, have measured large-angle elastic scattering of π+, π- and Κ- off hydrogen at 20 and 30 GeV/c. Near 900 c.m. the π-p cross section decreases as s with n ~ 9.5 while for smaller angles n ~ 8. This latter value is in agreement with the dimensional counting rule. Although some results agree with predictions of the constituent interchange model, there are also some disagreements. Further measurements have been made at 20, 50 and 9.2 GeV/c covering the |t| range from 1 to 8 GeV2.

The Clermont Ferrand-Leningrad-Lyon-Uppsala Collaboration, NA8, have measured small-angle elastic scattering of π+, π- and protons of 100 to 300 GeV and the data are now being analysed.

The Freiburg-Moscow (ITEP) Collaboration, NA6, have taken data on small-angle neutron scattering. Some 107 events have been recorded on tape in the ranges 0.04 ≤ |t| ≤ 0.14 and 0.001 ≤ |t| ≤ 0.016 GeV| for four energy bins.

The CERN-Padova-Tries te-Vienna Collaboration, WA6, have measured elastic scattering of protons of 150 GeV/c from a polarized proton target over the |t| range 0.4 to 3 GeV2. The polarization data are consistent with models which predict that there should be a cross-over from negative to positive values at t-values corresponding to the dip observed at |t| ~ 1.5 GeV2 in the differential elastic scattering cross section. Further data will be taken at 200 GeV/c.

The WA3 Collaboration, from results of a study of the reaction π-p → π+π-n at 63 GeV/c, have determined the elastic π+π- cross section by isolating the pion-exchange contribution in the mass range from 2 to 4 GeV. The resulting ππ differential cross section shows exponential behaviour for |tππ| < 0.7 GeV2 and it can also be described up to 600 c.m. by a Regge (ρ + f) and a Pomeron contribution, the latter being very small (~ 4 mb). The total ππ cross section was determined from the optical theorem point.

The WA10 Collaboration using π±, Κ±, p± beams of 50 GeV have obtained samples of 10 000 to 100 000 events of many exclusive channels, for which some results were given in sect. 1.1.1. Amplitude analysis is in progress for the channels K±p → Κ*±p with Κ* → Κ0π; π0p → X±p with X → K0K±;

Κ±p → Κ*±p with Κ*± → Λρ and with measurement of the Λ polarization; Kp → KKKp.

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The CERN-Neuchâtel-Paris (Collège de France) Collaboration, WA13, have measured in the Omega spectrometer two-body processes near 900 c.m. at 3 to 12 GeV/c and is finishing the analysis. The Collaboration have now performed the first experiment, WA55, in the Omega prime spectrometer, which is Κ+p elastic scattering at 12 GeV/c.

1.1.8 Hadrons in BEBC

The Brussels-CERN-Genova-Mons-Nijmegen-Serpukhov-Tel Aviv Collaboration, WA27, have taken 120 000 more photographs of 70 GeV/c K+ in BEBC. The External Particle Identifier, EPI was operational and the analysis of the results is very encouraging. Some photographs of Κ+ in deuterium were also taken but the run had to be terminated early. A comparison of the data for slow proton production in the reaction Κ+p → p + anything, with a simplified triple-Regge parameterization of this reaction at 32 GeV/c, indicates the dominance of Pomeron exchange. Comparison of this reaction and Κ+p → Δ++ + anything, with corresponding Κ+p reactions at 32 GeV/c and pp reactions at 69 GeV/c shows evidence for factorization. Inclusive single particle distributions of negative secondaries in 70 GeV/c Κ+p reactions are compared with data at lower energies and confirm "early" scaling in the target and fragmentation regions, whereas the cross section in the central region rises with energy. The invariant transverse momentum distribution in the central region shows thermodynamical behaviour when expressed in terms of transverse mass mT = (p2T + m2)½.

The Aachen-Berlin-CERN-London-Vienna-Warsaw Collaboration, WA28, have taken 80 000 additional photographs with a 110 GeV/c Κ- beam. Together with the 30 000 photographs taken in 1977 this should give 25 000 well-tagged

Κ- events. Fragmentation distributions of mesons were obtained and interpreted in terms of quark parton models. A simple relation between the fragmentation distributions in hadron-hadron interactions and quark fragmentation functions is observed. The quark distributions

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in the kaon, estimated using the recombination model, are found to be similar to the pion structure functions. At large transverse momentum the cross section for multiparticle systems (jets) is an order of magnitude larger that for single particles. This and other features of the data are consistent with results at larger p┴ obtained by a counter experiment at 200 GeV/c which had been interpreted as evidence for a new dynamical mechanism in hadron-hadron interactions. However, similar features are observed in a Κ-p experiment at low energy (16 GeV/c).

Results on single electron production by π- and of 70 GeV/c in a hydrogen filled TST, WA30 and 31, are given in sect. 1.1.3.

1.1.9 Large transverse momenta

The Bari-Cracow-Liverpool-Nijmegen-Munich (MPI) Collaboration, NA5, started taking data in May 1979 without the calorimeter. About 120 000 events of p and interactions at 200 GeV on hydrogen, argon and xenon targets were recorded. Since September the full apparatus is operational and so far (end October) 8000 events of π- and p on a hydrogen target inside the streamer changer were collected with a 340 GeV beam. It was required that the sum of the transverse momenta was greater than 10 GeV. Data taking is continuing.

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1.1.10 Reactions on nuclei

The Heidelberg-Virginia-Warsaw Collaboration, WA35, have taken data in 1977 on π, Κ, p, and interactions with nuclei at 20 and 40 GeV, using the unseparated S1 beam. It was found that:

(a) The characteristics of knock-out nucleons and of pions at low pseudo-rapidities are both energy independent.

(b) A systematic deviation from KNO scaling is observed. This gives further support to the "standard picture" of the hadron-nucleus interaction and it contrasts with predictions of the coherent tube model.

(c) The regularity observed for the angular distribution of fast secondaries as a function of the number of slow particles can only be explained by combining features predicted by different models.

1.1.11 Search for long-lived particles

The Bologna-Saclay (CEN) Collaboration, WA33,have searched for long-lived particles (lifetime ≥ 10-8 s) with charges ± 2/3, ±1, ± 4/3 and

±2 produced in pN collisions at 200 GeV. Upper limits were obtained which depend on the mass of the supposed particle. For charge -1 particles the limits are at the level of 10-7 of the pions at a mass of 0.2 GeV and reach 10-11 for 3 to 8 GeV mass. The following cross sections for light anti-nuclei were measured: (1.3 ± 0.3) and (1.9 ± 0.3)×10-34 cm2/ster. GeV/c for He-3 at 21 and 47.4 GeV/c respectively and (7.6 ± 0.9)×10-34 cm2/ster. GeV/c for at 23.7 GeV/c.

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1.2 Neutrino Physics

1.2.1 Introduction

Neutrino experiments continue to be extended and improved. The shielding against muons has been upgraded to allow running wideband beams with protons of up to 450 GeV. The CERN-Dortmund-Heidelberg-Saclay Collaboration, WA1, are now analysing data taken with a hydrogen target in front of their apparatus and are building a new apparatus to be ready early in 1981. The CERN-Hamburg-Amsterdam (NIKHEF)-Rome-Moscow, CHARM Collaboration, WA18, have started running with their complete apparatus. Their detector is also being improved to study neutrino-electron scattering. These two groups plus the Aachen-Bonn-CERN-London-Oxford-Saclay Collaboration, WA52, have performed a second Beam Dump experiment. The Amsterdam (NIKHEF)-Bologna-Padova-Pisa-Saclay-Torino Collaboration, WA25, have run with BEBC filled with deuterium taking 126 000 photographs with 26 000 events with neutrinos and 60 000 photographs with 11 000 events with antineutrinos. Preparations are being made to add a picket fence of counters inside BEBC. Additional cracks have been found in the Gargamelle bubble chamber which have stopped any further repair of the chamber. The Bologna-CERN Collaboration, WA44, have started a search for quarks.

1.2.2 Lifetime of charm particles

The Ankara-Brussels-CERN-Dublin-London (U.C.)-Pisa-Rome-Turin Collaboration, WA17, exposed in 1977 30 litres of emulsion, placed in front of BEBC to the wideband neutrino beam. The BEBC photographs yielded 400 predictions of events in the emulsion of which 170 have been located. Three examples of decays of positively charged particles and three of the decays of neutral particles have been found (these latter are the first observed). These six events are attributed to decay of charm particles, the probability that either type could be due to background is negligible (< 10-7). One event is a unique example of charmed baryon Λ+c, decaying

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after a flight time of (7.3 ± 0.1) × 10-13 s via the pK-π+ mode. The other two charged particles yield lifetimes between (0.5 and 5) × 10-13 s while the three neutral particles yield proper times of ~ 10-13 s.

1.2.3 Charm production

The Aachen-Bonn-CERN-Munich-Oxford Collaboration, WA21, have observed two events, each giving three-constraint kinematical fits, in which an excited charmed meson D*+, decays into D0π+, with the mass difference ΔΜ = M(D*+) - (MD0) = 145.2 ± 0.6 MeV. The inclusive cross section for D production has been determined for all events by assuming that each negative track in turn is a K- and studying ΔΜ distributions as the error on ΔΜ is small. It is found that the production rate of σ(νp → μ-D*+ + anything) relative to σ(νp → μ- + anything) above the D threshold is (4.2 ± 2.4)%.

1.2.4 Structure functions

The CDHS Collaboration have measured the structure functions F2(x, Q2) and xF3(x, Q2) in high-energy neutrino charged current interactions on nuclei and compared the results with QCD predictions. Solutions to the moment equations of QCD are found which are in good agreement with the data and yield simple parameterizations of the structure functions. For the scale parameter Λ, a value is found of Λ = 0.5 ± 0.2 GeV. The analysis also gives values of the width of the gluon distribution as a function of Q2. It is found that <x>gluons = 0.16 ± 0.03 for Q2 = 10 GeV2.

1.2.5 QCD effects at the hadronic vertex - fragmentation functions

The ABCMO Collaboration, WA21, have studied inclusive distributions of single hadrons in CC neutrino-hydrogen interactions. Contrary to the naïve parton model predictions, evidence has been found for non-factorization at fixed q2,i.e. the hadron and leptonic vertices cannot be treated separately. Analysis of double moments of fragmentation functions show scaling functions in agreement at high q2 with QCD predictions with

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Λ = 0.75 GeV. Analysis of quark singlet moments yields moments of the gluon distribution. It is found that for q2 = 10 GeV2, the gluon moments are 1.0 to 1.5 times the average quark moments, which indicates that the quark and gluon fragmentation functions are rather similar. Other indications of QCD effects, such as an anomalous increase of <p┴2> with q2, have been observed by the ABCMO and ABCLOS Collaborations.

1.2.6 The reaction νμe- → μ-νe

The purely leptonic CC reaction νμe- → μ-νe has been observed in Gargamelle and measured for the first time by the Bari-CERN-Milan-Orsay-Palaiseau (Ecole Polytechnique) Collaboration, WA14. The total of 26 events above background lead to a cross section in agreement with standard V-A prediction.

1.2.7 The reaction μe- → μe-

The CERN-Hamburg-Amsterdam (NIKHEF)-Rome-Moscow (ITEP) Collaboration, WA18, have measured a sample of 73 000 neutrino interactions with shower energies in the range 5 to 50 GeV. Among these, 6.5 ± 3.6 have been selected which can be attributed to the reaction νμe- → νμe- and which lead to a cross section of σ/Εν = (2.6 ± 1.4) × 10-42 cm2/GeV which agrees with earlier measurements. These results show that this experiment is feasible using an electronic, non-visual fine-grain calorimeter. The statistics are being increased by a factor of ~ 10.

The WA14 experiment has found in Gargamelle 9 events (of which 0.5 are background) of the reaction νμe- → νμe-. The slope of the cross section versus energy curve is found to be 2.4 ± 10-42 cm2/GeV, which corresponds to sin2 θW = 0.12 ± . No event was found in the anti-neutrino beam by the Aachen-Bergen-Brussels-Strasbourg-London(UC) Collaboration, WA15, which corresponds to a slope of < 2.7 × 10-14 cm2/GeV and sin2 θW < 0.39.

The Bari-Birmingham-Brussels-London(UC)-Palaiseau (Ecole Polytechnique)-Rutherford-Saclay (CEN) Collaboration, WA24, searched film of BEBC, equipped with a Track Sensitive Target (TST) filled with hydrogen

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and surrounded by a neon-hydrogen mixture for Weinberg electrons produced by antineutrinos. Only one ambiguous candidate was found, consistent with theoretical expectation and excluding very high values of the Weinberg angle suggested by previous Gargamelle results.

For antineutrinos the CHARM Collaboration have found in 160 000 semi-leptonic charged current events 41 ± 10 events of the reaction → giving a preliminary cross section value of σ/Ε ~ (1.8 ± 0.4) × 10-42 cm2/GeV.

1.2.8 Neutral currents

The CHARM collaboration, WA18,have measured 9 200 neutrino and 2 700 antineutrino reactions in a fine-grain calorimeter using the 200 GeV narrowband beam. The corresponding ratios R = σ(NC/σ(CC) are R = 0.30 ± 0.006 ± 0.02 and = 0.39 ± 0.014 ± 0.02 where the first error is statistical and the second is the present estimate of systematic uncertainties.

The CDHS Collaboration used 21 700 neutrino and 4500 antineutrino reactions to obtain R = 0.307 ± 0.008 and = 0.373 ± 0.025. A value of Sin2 θw of 0.228 ± 0.018 is obtained,

The ABCLOS Collaboration, WA19, determined the hadronic energy distribution for NC interactions of neutrinos and antineutrinos from the narrowband beam in BEBC filled with a neon-hydrogen mixture. The results show that the contributions from scalar or from pseudoscalar forms of the interaction are consistent with zero and that pure V, A, and V + A are excluded. A determination of the left- and right-handed couplings to the u and d quarks are made in the form (u2L + d2L) and (u2R + d2R).

The ABCMO Collaboration, WA21, studied NC interactions produced by neutrinos from the wideband beam. BEBC was filled with pure hydrogen. By combining the results for R = σ(NC)/σ(CC) for hydrogen with those from WA19 for an isoscalar target, so that the ratio of u to d quarks in the target is different, the coupling parameters were found,

u2L = 0.15 ± 0.05 ± and dL = 0.17 ± 0.07 ± giving Sin2 θW = 0.19 ± 0.03 ± 0.02 where the first error is statistical and the second systematic.

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1.2.9 Like-sign dimuons

A large sample of like-sign dimuons has been analysed by the CERN-Dortmund-Heidelberg-Saclay (CEN), CDHS, Collaboration, WA1, from data recorded in positive and negative wideband beams. 290 events of the type νN → μ-μ-X and 53 events of the type → μ+μ+X with Εν > 30 GeV and muon momenta > 6.5 GeV/c, show evidence for a prompt signal of like-sign dimuon production. After subtracting the background from single events with μ or Κ decay in the hadronic shower, a rate of prompt like-sign dimuon production of (3.4 ± 1.8) × 10-5 for neutrinos, and of (4.3 ± 2.3) × 10-5 for antineutrinos relative to single μ events, has been measured.

1.2.10 Trimuons

A clear signal of trimuon production by antineutrinos has been found by the CDHS Collaboration, WA1. Eight observed events with the signature μ+μ+μ- seem consistent both in rate and in average kinematical parameters with trimuon events produced by neutrinos. The average rate of μ+μ+μ- production by antineutrinos is (1.8 ± 0.6) × 10-5 relative to the single μ rate, for visible energy ≥ 30 GeV and muon momenta ≥ 4.5 GeV.

1.2.11 Polarization of positive muons

In a joint experiment the CHARM and the CDHS Collaborations, WA18 and WA1, respectively, have determined the polarization of positive muons produced in antineutrino CC interactions. The CDHS detector served as target and provided the trigger and the relevant kinematical parameters. The CHARM detector analysed the direction of the muon spin with respect to the muon momentum vector. A positive polarization of 1.09 ± 0.22 has been found, consistent with helicity +1 as expected in V-A theory.

1.2.12 Quark search

The Bologna (INFN and Univ.)-CERN Collaboration, WA44, are searching for fractionally charged quarks produced by neutrino interactions in lead. The specific ionization of the secondaries is measured by an avalanche

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streamer chamber as well as scintillation counters. So far in ν and wideband beams 18 000 and 21 500 pictures have been obtained. In a preliminary scan of 1 500 pictures a two-track separation of 1.2 mm was found and the ionization resolution for minimum ionizing particles has been measured to be within expectations. No quark candidates have been observed so far.

1.2.13 Prompt lepton production - beam dump exgeriment

A second beam dump experiment has been performed to confirm with higher statistics a prompt neutrino flux discovered in December 1977 in BEBC, Gargamelle and the WA1 apparatus. The experiment was performed by the ABCLOS Collaboration, WA52, the CDHS Collaboration, WA54 and the CERN Collaboration, WA18. The use of targets of variable effective density allowed a direct measurement of the prompt neutrino signal by extrapolation to infinite density. The monitoring of the beam showed that beam scraping could not be the origin of the effect. Positive effects were observed in all three experiments and the rates were consistent with equal fluxes of prompt νe, , νμ and . From the BEBC results, a flux of (3.7 ± 1) × 10-8 νe/(proton. sr) is obtained for Ε > 10 GeV in the forward direction (< 1.8 mrad) from 400 GeV protons. If D-mesons are the principal source of neutrinos, then production cross sections of 15 to 30 μb/nucleon are obtained for production assuming a linear Α-dependence (or 40 to 85 μb if the production cross section is proportional to the proton absorption cross section).

1.2.14 Results using the TST

The Bari-Birmingham-Brussels-London (UC)-Palaiseau (EP)-Rutherford-Saclay (CEN) Collaboration, WA24, took ~ 550 000 photographs in the wideband neutrino and antineutrino beams in 1978 using BEBC equipped with a Track Sensitive Target (TST). Abnormal dirt problems, unassociated with the TST, have greatly slowed scanning and measuring of the thin-track events inside the TST. After a search for Weinberg electrons, an EMI-directed search for multimuon events in the film was performed. A flux-independent measurement of the ratio of CC neutrino cross sections on neutrons and protons was made. The measurement of events originating in the TST is continuing.

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1.3 Muon experiments

1.3.1 Structure functions

The Annecy (LAPP)-CERN-Hamburg (DESY)-Freiburg-Kiel-Lancaster-Liverpool-Oxford-Rutherford-Sheffield-Shrivenham-Turin-Wuppertal Collaboration, NA2, have taken data on muon scattering off hydrogen, deuterium and iron targets at different muon beam energies between 120 and 280 GeV. Preliminary results on the F2(x, Q2) structure function in iron show good agreement with the nucleon structure function determined by the CDHS Collaboration WA1, from neutrino scattering, when the weight of the contributing quark charges is taken into account by multiplying the neutrino results with the factor 5/18 in agreement with the picture of non-integrally charged quarks contributing to deep inelastic lepton scattering. Data on the F2 structure function taken with a hydrogen target have also been presented and are in agreement with QCD predictions.

The CERN-Dubna-Munich-Saclay Collaboration, ΝΑ4, have taken data on 1.6·106 deep inelastic muon interactions in carbon over the energy range 120 to 280 GeV. Results on the F 2(x, Q2) structure function have been presented for 280 GeV muons (15% of the sample containing 10 000 μ+ scatters with Q2 > 50 GeV2) and 120 GeV muons (10% of the total containing 29 000 μ+ scatters with Q2 > 25 GeV2). After correcting for the 5/18 factor, satisfactory agreement is obtained with WA1 neutrino scattering results. The data covering the Q2 range 30 to 220 GeV2 and 0.2 < × < 0.7, are consistent with little or no scaling violation.

1.3.2 Multimuon production

The European Muon Collaboration, NA2, have measured elastic and inelastic J/ψ production by virtual photons where the J/ψ decays into μ+μ-. The naïve vector dominance model for the elastic production by transversely polarized photons predicts a Q2 dependence of the form (1 + Q 2/m J / ψ) - 2. A fit of the form C(1 + Q2/M2)-2 with C and M as free parameters is in good agreement with the data giving M = 2.4 ± 0.3 GeV.

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In the NA4 experiment final states yield a (μ+μ-) spectrum with masses up to 11 GeV/c. In the restricted mass region around the upsilon mass, the number of events observed is 24, while the number calculated assuming electromagnetic trident production by the Bethe-Heitler and Compton processes is 30. An upper limit on upsilon production cross section is then

σT × BR (Τ → μ+μ-) ≤ 0.6 × 10-38 cm2/nucleon with 90% confidence.

1.3.3 Future muon experiments

The NA2 experiment is adding a lead glass photon detector to the forward spectrometer to study single photon, π0 and η inclusive distributions. A polarized target is being developed to study the interaction between longitudinally polarized muons and longitudinally polarized protons.

The Aachen-Annecy (LAPP)-CERN-Freiburg-Hamburg (DESY and University)-Kiel-Lancaster-Liverpool-Mons-Munich-Orsay-Oxford-Rutherford-Sheffield-Turin-Wuppertal Collaboration, NA9, are adding a vertex detector (including a streamer chamber) and backward particle detector to the NA2 apparatus. The work is progressing satisfactorily.

The NA4 experiment is continuing to collect data and the apparatus is being improved in order to eliminate possible sources of systematic errors.

1.4 SPS collider

The Aachen-Annecy (LAPP)-Birmingham-CERN-London (QMC)-Paris (Collège de France)-Riverside-Rome-Rutherford-Saclay (CEN)-Vienna Collaboration, UA1, have all major components either well advanced or ordered.

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(a) Spectrometer magnet (CERN) and hadron calorimeter (Birmingham, QMC) are being preassembled, tested and measured in Building 156. The quality of the delivered parts of the magnet exceed specifications. The implementation of the hadron calorimeter (6000 plates of scintillator, 12 000 BBQ-bars and light guides) has been satisfactorily tested on one of the magnet components.

(b) Central detector and electronics (CERN) - the very ambitious project of the image chamber has met with a number of difficulties mainly in connection with the mechanical construction of the transparent self-supporting structure. A model chamber with the full-size wire configuration was successfully tested and confirmed the validity of the concept.

(c) Electromagnetic shower counters (Saclay, LAPP) are in production.

(d) Forward detectors (Collège de France, INFN Roma, Riverside) - the production of components is on schedule.

(e) Muon chambers (Aachen) - the mechanics of the muon detector (60 chambers of 4 × 5 m2, 4 wire planes each) is ordered. The electronics are being developed with CERN.

It is still believed that the detector will be capable of collecting physics when the ring operates.

The Berne-CERN-Copenhagen (NBI)-Orsay (LAL)-Saclay-Pavia Collaboration, UA2, detector is being constructed and matches the progress of the civil engineering work. The main parts are:

(a) Vertex detector (Orsay) full-scale prototypes of a drift chamber sector and of a cathode strip proportional chamber are under construction and will be tested in 1979.

(b) Central calorimeter (CERN) - a full-size prototype of a calorimeter module has been produced and is being tested in beam H5. Assembly will start in January 1980 at the rate of one module/week.

(c) Magnets (CERN) - both toroid and wedge magnets have been ordered.

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(d) Wedge detectors (Saclay, CERN) - scintillator hodoscopes, lead glass array and drift chambers are being modified and will be completed in 1979.

(e) Drift chambers (Copenhagen, Pavia) - a full-size prototype chamber is under test. From April 1980 each institution is to produce one chamber per week for 40 weeks. (f) Multitube chambers (Berne) - main orders have been placed.

(g) Forward-backward calorimeters (Saclay) - a two-cell module has been successfully tested and orders placed.

(h) Supports, services (CERN) - design is progressing on schedule.

(i) On-line computing (CERN) - a VAX 11/780 has been ordered.

The Annecy (LAPP)-CERN Collaboration, UA3, are designing their detectors of magnetic monopoles to fit in place.

The Amsterdam-CERN-Genova-Napoli-Pisa Collaboration, UA4, have finalized the layout of detectors and vacuum chamber in their experiment to measure elastic scattering and total cross section. The construction of the vertex detectors has started and two prototype drift chambers have been built. The mechanical design of the movable vacuum chamber ("Roman pots") was completed and a prototype is being built. A data acquisition system has been designed.

The Bonn-Brussels-Cambridge-Stockholm Collaboration, UA5, are constructing their equipment and aim to test it on the ISR after the main shutdown (October-November 1980). Parts will be tested at the ISR starting April 1980. The first of the two 6 m streamer chambers is under construction at CERN. The 2.7 m Munich streamer chamber is being used for performance tests. The optics are defined and the first of the 90 mm diameter image intensifier tubes should be delivered in December 19 79. The triggering system and its logic are designed and will be tested soon. The laboratories are testing data analysis problems of the expected complicated events by measuring computer simulated events on film.

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2. ISR PROGRAMME

At the ISR, the hadronic production of charmed baryons and of large pT single photons have been observed for the first time. New results have come from lepton pairs, meson production at small and large pT values and from correlations between mesons.

2.1 Charm production

Production of the charmed baryon Λ+c has been observed by two Collaborations. The Annecy (LAPP)-CERN-Collège de France-Dortmund-Heidelberg-Warsaw Collaboration, R407/408 and R416, have observed a sharp peak at 2.26 GeV in the decay mode Λ+c → in events triggered with a forward Κ- produced in pp collisions at √s = 52.5 GeV. Evidence is also found for the Κ-Δ++ decay mode and a cross section is obtained for Λ+

production of 30 to 60 μb depending on the production model assumed. Evidence is also found at √s = 61.5 GeV for Λ+c → pK-π+ when it is required that an electron be also produced. To study charm production in the central region, analysis is in progress of a few times 105

complete events associated to a clean prompt electron candidate (for PT ≥ 0.5 GeV/c).

The Aachen-CERN-Harvard-Munich University-Northwestern-Riverside Collaboration, R606, have observed the Λ+c decay into pΚ-π+ and Λπ+π+π- at a mass of 2.255 GeV. The results indicate a non-central production mechanism since the Λ+c particles are observed at large values of Feynman x

(0.3 < xc < 0.8) and in association with a recoil proton 0.8 < xp < 0.975. The cross section measured in these conditions is 0.7 to 1.8 μb for the pK-π+ final state which would correspond to a total Λc cross section of ~ 100 μb.

The CERN-INFN Bologna-INFN Frascati-University of Bologna Collaboration, R415, have obtained 1.2 × 107 events in the Split Field Magnet with a single electron near 900 as trigger. First priority has been given to 800 events in which the electron is accompanied by an identified K-meson. From these eK events it has been shown that the total cross section for inclusive D0-production is less than 1.7 μb for a production cross section of the form

σinvariant α e-1.6pT.(1 - x)4.3.

The CERN-Los Angeles-Saclay Collaboration, R608, are extending their R603 apparatus, improving the acceptance by a factor of 100, and will further study charmed particle production.

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2. 2 Single photon production

The Athens-BNL-CERN Collaboration, R806, have measured single photon production in pp collisions at 30 < √s < 62 GeV, in liquid argon-lead calorimeters. The rates remain approximately constant with increasing energy, √s For fixed √s, the γ/π0 ratio increases strongly with increase in pT being ~ 0.2 for pT > 4.5 GeV/c. The CERN-Copenhagen-Lund-Rutherford-Tel Aviv Collaboration, R807, have started to use their apparatus together with the R806 single photon detector. The aim is to obtain multiplicity information from the barrel counter hodoscope.

The CERN-Columbia-Oxford-Rockefeller Collaboration, R108, have obtained for single photon production a value of γ/π0 of ~ 10% at pT of 10 GeV/c.

2.3 Lepton pair production

The Frascati-Harvard-MIT-Naples-Pisa Collaboration, R209, are completing their data taking on dimuon production at √s = 62 GeV. So far an integrated luminosity of 1.25 × 1038 cm-2 has been obtained. Some data have also been taken at √s = 44 GeV to test scaling. The mass spectrum for dimuons extends up to a mass of 20 GeV. In a search for higher mass events, two have been found with a mass of 25 GeV and one with a mass of 28 GeV. The angular distribution of single muons in the dimuon rest frame has been found to be ~ 1 + cos2θ except near the upsilon mass where it is flat.

The CCOR experiment, R108, in a study of massive electron pairs finds that the <pT> of the pair is considerably higher at ISR energies, √s = 62 GeV, than at Fermilab energies (√s = 27 GeV). The experiment is being extended and, as R110, will have a five-fold increase in the acceptance for high-mass e+e- pairs.

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2.4 Large transverse momentum physics

The ABCS Collaboration, R806,have measured π0 production at √s = 62 GeV at very large pT values, up to 15 GeV/c. It is found that the differential cross section decreases more slowly with pT than the pT-8

behaviour that has been observed at lower values of pT. This is in qualitative agreement with QCD predictions. The inclusive η cross section has been measured out to 11 GeV/c and the corresponding η/π0 cross section has an average value of 0.55 ± 0.07 and varies little with pT.

The Open Axial Field Spectrometer of the CCLR Collaboration, R807, is ready to start measuring the inclusive spectra of charged hadrons up to pT ~ 12 GeV/c plus the energy flow in the opposite hemisphere.

The CCOR Collaboration, R108, have taken further data on π0 production at high pT and on π0-π0 pairs of high invariant mass (> 10 GeV) with a view to testing QCD predictions.

2.5 Resonance production and studies of the reaction mechanism

The CERN-Holland-Manchester Collaboration, R207, studied the reaction p + p → p + p + X where each proton had a momentum in excess of 80% of the momentum of the primary beam. Signals for the production of ρ, ω, f and A2 mesons are observed in the missing mass spectra. It is concluded that the bulk of the final states are not produced through double Pomeron exchange. In the continuation of this experiment, the Amsterdam-Louvain-North Western Collaboration, R607, studied p + p → π + π + Χ where a substantial fraction (> 50%) of the available energy per primary proton is transferred to a single pion. The pions in π+π+, π-π- and π+π- pairs are found to be essentially uncorrelated. The results are inconsistent with quark exchange and only consistent with gluon exchange under further assumptions. The production of high-momentum Λ, , Λ0(1520), Φ(1020) and has been observed.

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2.6 Magnetic monopole search

The CERN-Rome Collaboration, R109, have found no magnetic monopole in the plastic detectors exposed to a luminosity of 8.5 × 1037 cm-2

It is concluded that the cross section for production of free monopoles with masses smaller than 30 mP and n-values of charge ≤ 3, is smaller than 10-37 to 10-36 cm2.

The Annecy (LAPP)-CERN Collaboration, R501, have irradiated three sets of Kapton foils inside the machine vacuum with an integrated luminosity of 7.4 × 1037 cm-2. The foils were analysed by chemical etching and no monopoles were detected. The experiment is continuing.

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3. PS PROGRAMME

The PS programme is confined to the East Hall for physics, using only the South Hall to provide test beams for calibrating and testing experimental detectors. The LEAR facility to provide intense beams has been approved and will be situated in the South Hall. The future PS programme of physics experiments and test beams using standard extracted beams will all have to be accommodated in the East Hall.

3.1 Counter experiments

The experiments PS 153 and PS 157 (CERN-Collège de France-Ecole Polytechnique Collaboration) which use large parts of the same apparatus have now completed their data taking using negative pions of momentum between 2-14 GeV/c. Preliminary results of these experiments which studied the behaviour of the total cross section and large-angle elastic scattering with high precision as a function of 22 different incident momentum to look for the on-set of narrow structures do not show any such effects at the present level of the analysis. The group plan to take total cross section data at the same level of precision using positive pions.

At present the experiment PS 164 (Aarhus-CERN-Strasbourg Collaboration) is now installed in this beam line to study channelling effects.

Experiment PS 159 (CERN-Rome-Saclay-Vanderbilt Collaboration) is studying the reaction Κ-D → Κ+ + missing mass, in order to look for dibaryon candidates of strangeness -2 using kaons in a separated beam of 1.4 GeV/c. Emphasis is placed on having a very good momentum measurement and signature of the incoming and outgoing kaon and this has been tested using the reaction Κ-p → Κ+Ξ- and π-p → Κ+Σ-. The results on the measurement of the baryon missing mass spectrum gave an inherent mass resolution of ± 5 Mev consistent with calculations. The experiment is running to obtain high statistics for a sensitivity of 40 evt/nanobarn at the production.

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Experiment PS 161 (Basel-Karlsruhe-Stockholm-Thessaloniki Collaboration) has been running in order to look for-high energy gamma rays occurring in the decay of baryonium.

Experiment PS 165 (Birmingham-Rutherford-Surrey Collaboration) is preparing to measure the 2p-1s kaonic hydrogen X-rays produced by kaons stopping in liquid hydrogen. The aim is to deduce the Κ-p scattering length at threshold.

The Edinburgh-Rutherford-Westfield College Collaboration, PS160, have tested their beam and equipment and are ready to start measuring the A and R parameters in the reaction π+p → Κ +Σ +.

The Aarhus-CERN-Strasbourg Collaboration, PS 164, are testing the equipment in the d31 beam. They are studying X-ray production due to channelling effects of particles going through crystal, and are measuring their scattering angle at very small transverse momentum.

3.2 Hadron physics in bubble chambers

The CERN-Collège de France-Madrid-Stockholm Collaboration have reached their final statistics of 90 ev/μb for 4 GeV/c π-p reactions. The poorly established Ε-meson has been studied in the reaction π-p → En. A mass-independent partial wave analysis of the decay Dalitz plot (Ε → ) strongly favours the spin-parity assignment 1+ and charge conjugation C = +1. The same analysis results in the branching ratio (E → Κ*Κ)/(Ε → δπ + Κ*Κ) = 0.86 ± 0.12 with δ → . The non-observation of a charged Ε-meson shows that 1 = 0. The complete quantum numbers of the Ε-meson are therefore IGJPC =0+1++. The mass and width are found to be 1426 ± 6 MeV and 40 ± 15 MeV respectively.

In the 4.2 GeV/c Κ-p experiment, Amsterdam-CERN-Nijmegen-Oxford Collaboration, a partial wave analysis of the 3π system produced backwards in the reaction Κ-p → Σ-π+π+π- has established a phase variation for the

JP = 1+, ρπ enhancement at a mass of 1041 ± 13 MeV with a width of 230 ± 50 MeV, thus confirming the resonant nature of this A1 enhancement.

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In a study of Κ-p interactions at 8.25 GeV/c, the Birmingham-CERN-Glasgow-Michigan State-Paris LPNHE Collaboration have observed a narrow Y* with a mass of 3170 MeV and a width ≤ 20 MeV decaying to Σ + pions, Λ + pion and ΞΚ + pions. The sequential decay ω(1670) → Βπ → ωππ has also been observed.

In the analysis of 16 GeV/c π±p and Κ-p interactions, the Aachen-Berlin-Bonn-CERN-Cracow-Innsbruck-London-Vienna-Warsaw Collaboration have

published additional results including (1) study of inclusive Κ* production in π+p reactions and in pp reactions at 12 and 24 GeV/c (this jointly with the Bonn-Hamburg-Munich Collaboration). It is found that 30% of the observed Κ0 particles come from Κ* decay. The Κ*+ production spectra are similar for both reactions in the target hemisphere but there is more forward Κ*+ production by π+ than by protons at 24 GeV/c. The Κ*- spectra are similar for π+p and Κ-p reactions over the whole kinematic region when viewed in the quark c.m.s. and point to a central production mechanism. Comparing Κ*+ and ρ0 production striking similarities are found, the Κ* production rates being ~ 20% of the ρ0 production cross sections. (2) Inclusive production of Σ+ and Σ- hyperons has been studied in 10 and 16 GeV/c Κ-p interactions. Comparison with Λ production shows features which can be considered intermediate between those for

Σ+ and Σ- but the cross section is ~ 2 times greater. (3) Inclusive phi production (sect. 1.1.3).

The CERN-Soviet Union and France-Soviet Union Collaborations are analysing Κ-p interactions observed in the Mirabelle bubble chamber exposed to a 32 GeV/c beam at Serpukhov. Some twenty papers are being written on inclusive and exclusive reactions. Of particular interest are results on vector and tensor meson production and on diffractive proton fragmentation containing quarks.

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4. SC PROGRAMME

The SC programme went into 1979 with an average of 14 active experiments. After a three-weeks' maintenance shutdown the cyclotron was started up with 400 MeV 3He for the Cagliari-Strasbourg-Torino Collaboration, SC75. By further analysis of their earlier 3He data, which showed evidence for the observation of the doubly coherent two-body final-state reaction 3He + 6Li → 9C + π-, it is found that the rate of high-energy π- is 100-1000 times higher than expected from a simple estimate on the basis of the elementary production process NN → ΝΝπ. New data were taken on 3He reactions with 9Be, 12C, 27A1 and 208Pb to measure the mass dependence. A preliminary analysis indicates the possible observation of the two-body final state 12N + π-.

With the start, beginning March, of a 2½ month maintenance period the most productive period in the history of ISOLDE Collaboration until now was completed. Several of the key experiments finished their data taking and have left the floor and several new experiments are in progress. One of the most striking results is the first observation of beta-delayed two-neutron emission from the 8.5 ms isotope 11Li which was first discovered at the CERN PS. It beta-decays to a resonance at 8.84 MeV in 11Be which desintegrates into 9Be and two neutrons. A series of experiments has been performed to measure the masses of Rubidium isotopes. In a joint CERN-Jülich experiment the first excited level of 132Su has been observed at 4.041 MeV and shown to be 2+ and not 3- as was previously believed. A new experiment with application to solid state physics, makes use of ISOLDE's intense beams of radioactive ions for studies of implantation using the Mossbauer effect to detect tin defect structures in semiconductors.

A beam of 12C has been successfully accelerated with 1 μΑ current and up to 86 MeV/N. It will be used for several experimental Collaborations, CERN-Copenhagen-Grenoble-Lund (SC83)-Orsay (SC84)-Heidelberg (MPI)-Darmstadt (SC85) and Bordeaux-Gardigan (SC86).

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A μSR (muon spin rotation) Collaboration probe metals, semiconductors and organic radicals by means of muons as it has been realized that muon diffusion in metals is very strongly influenced by impurities. The interesting result obtained last year by the CERN-Geneva-Julich-Uppsala Collaboration, SC76,that no indication of muon spin relaxation can be detected in pure A1 has been confirmed also for temperatures down to 0.1 K. On the other hand Cu-metal and A1-alloys show a complicated behaviour over the 0.03 to 2 Κ range. Ferromagnetic materials have been studied by the CERN-Uppsala Collaboration, SC65. Coherent tunnelling seems possible in the purest Fe samples but carbon impurities destroys this. In iron and in nickel the pressure dependence of the local contact field has been measured up to pressures of 7 kbar. First measurements on Si and Ge by the CERN-Parma-Rutherford Collaboration, SC81, have indicated muonium signals at low fields and fairly high temperature (~ 200 K).

The CERN-London (IC)-Rutherford Collaboration, SC82, are using the muonium and μ+ SR technique to probe the physico-chemical behaviour of polymer systems at the molecular level. The experiments observe the formation of muonium from free muons, and subsequent chemical reaction: the observed decay times give information on chemical reactivity and molecular relaxation processes. Polymethyl-methacrylate, polysterene and benzene have been studied.

The reconstruction, after the fire, of the large-volume multiparticle spectrometer operated by the Omicron Collaboration has been completed and improvements made. The Amsterdam-Birmingham-CERN-Ljubljana-Oxford-Turin Collaboration, SC73, have studied pion backward scattering off light nuclei and ~ 10 triggers have been recorded.

The Pisa group, SC74, are measuring the population and lifetime of the 2S state of muonic hydrogen (μp). Data are now being analysed.

The Lund-Oslo Collaboration, SC79, have studied the binary fission of light nuclei by 600 MeV protons. Some deviations from the macroscopic-microscopic approach have been found.

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The radiobiological experiments using the 600 MeV neutron beam (CERN-Manchester-Rome Collaboration, SC78) are already giving some results. It has been found that the production of apotoses in mice crypt are produced for as low a dose as 0.5 rad and that the dose effect relation appears to be similar to that found earlier for spermatogonia survival in mice exposed to the 400 MeV neutron beam and a negative pion beam at the SC.

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5. NEW DEVELOPMENTS, STANDARDIZATION, DATA COMPILATION

5.1 New detectors

The main activities in detector development include:

(a) Possible applications of the avalanche streamer chamber are: (1) a high rate gated chamber for detecting very high fluxes of particles; (2) Čerenkov ring imaging in the far ultra-violet for particle identification; (3) radio-chromatography imaging.

(b) Čerenkov ring imaging has been realized using the single photon capabilities of the multi-step chamber.

(c) The photo-ionization proportional chamber couples the excellent energy resolution properties of gas proportional scintillation counters to the localization properties of MWPC. The first applications foreseen are in astrophysics.

(d) Data obtained last year at CERN from the proton radiography of a human head have been analysed. An improved set-up is now operational at Saturne in Saclay for further studies.

5.2 Electronics

The Electronics Research and Development Group has given design, development, production and commissioning support to many experiments. An effort is continuously being made to develop general purpose systems. Among the major projects are: (a) design of electronics for the central detector of UA-1, a system which provides three-dimensional track information and measures energy loss, by processing signals from image retaining drift chambers, is nearing completion; (b) electronics for drift chambers of R807; (c) development work on photon tagging system for NA14, it should derive a complex trigger from eight planes of scintillation counters (600) within 500 ns.

Major efforts have been made in the direction of standardization of data acquisition system elements, particularly for the CAMAC-ROMULUS series of compatible data buffers, processors and data routing devices. The outlines of the new data acquisition system FASTBUS have sufficiently advanced that prototyping can be started.

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5.3 Complilation of cross sections

The High Energy Reaction Analysis Group, HERA, has published three volumes of updated cross sections for reactions with beams of π±, Κ± and p± respectively.

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SPS EXPERIMENTS ON THE FLOOR IN 1979 Exp. No.

Experiment Collaboration Status

WA1 High-energy neutrino interactions CERN-Dortmund-Heidelberg-Saclay Data Taking WA6 Polarization in pp and πp elastic scatt. CERN-Padova-Trieste-Vienna Data Taking WA7 Two-body reactions at large pT Annecy-CERN-Copenhagen-Genova-London-Oslo Data Taking

WA11 Search for high mass slates produced with the Ψ(3.1)

London-Indiana-Saclay Data Taking

WA18 Study of semileptonic neutral-current processes and of μ-polarization produced in ν and interactions using counters

CERN-Hamburg-Amsterdam-Rome-Moscow (ITEP)

Data Taking

WA21 High energy ν and interactions in BEBC filled with hydrogen

Aachen-Bonn-CERN-Munich-Oxford Data Taking

WA22 Experiment in BEBC to compare neutral and charged current neutrino interactions induced by νπ and νK at the same energy

London (I.C.)-Saclay (CEN) Pending

WA25 Neutrino and antineutrino interactions in deuterium Amsterdam-Bologna-Padova-Pisa-Saclay-Torino Data Taking

WA27 K+p interactions in BEBC at 70 GeV/c Brussels-CERN-Genova-Mons-Nijmegen-Serpukhov-Tel Aviv

Data Taking

WA28 K-p interactions in BEBC at 110 GeV/c Aachen-CERN-Cracow-London (I.C.)-Vienna-Warsaw Data Taking

WA33 Systematic search for long-lived heayy particles

Bologna-Saclay (CEN) Completed 9.5.79

WA35 Measurement of the correlations between; emitted protons and pions in hadron-nucleus collisions for 60 to 150 GeV/c incoming momenta

Heidelberg (MPI) Data Taking

WA38 Magnetic monopole search at the SPS USSR-Bologna-CERN Data Taking WA42 An experiment on the strong interactions

of charged hyperons Bristol-Geneva-Heidelberg-Lausanne-London (Queen Mary)-Rutherford Data Taking

WA44 Search for quarks in high-energy neutrino interactions

Bologna (INFN and Univ.)-CERN Data Taking

WA46 Study of Σ- decays and of the Σ- → n e- decay mode Bristol-Geneva-Heidelberg-Orsay-Rutherford-Strasbourg Completed 28.5.1979

WA47 Continuation of the study of neutrino interactions with dichromatic beams at SPS, using BEBC filled with Neon

Aachen-Bonn-CERN-London (I.C.)-Oxford-Saclay (CEN)

Data Taking

WA49 Study of interactions involving baryon exchange using the Omega spectrometer

CERN-Liverpool Completed 31.10.1979

WA50 Biological effects of 200 GeV/c protons CERN Completed 31.10.1979

WA51 Study of π± interactions in BEBC at 25 and 60 GeV/c

Seattle-Strasbourg-Warsaw Completed 14.5.79

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Exp. No. Experiment Collaboration Status

WA52 A second generation beam dump exp. in BEBC Aachen-Bonn-CERN-London (I.C.)-Oxford-Saclay CEN Completed 28.5.1979 WA54 Beam dump experiment with 400 GeV protons CERN-Dortmund-Heidelberg-Saclay Completed

28.5.1979 WA55 Test of Omega Prime accuracy and Κ+p elastic

scattering at 12 GeV/c around 900 c.m. CERN-Neuchâtel-Paris

(Coll.de France) Completed 28.5.1979

WA56 Study of states produced via baryon exchange in π+p interactions using the Omega Prime spectrometer

CERN-Neuchâtel-Palaiseau-Paris (Coll.de France)

Data Taking

WA57 Studies of high mass vector meson photo-production in energy range 20 to 70 GeV

Bonn-CERN-Glasgow-Lancaster-Man-chester-Paris VI-Rutherford-Sheffield

Data Taking

WA58 Measurement of lifetime of charmed particles in nuclear emulsion exposed to an 80 GeV bremsstrahlung beam in conjunction with the Omega Prime spectrometer

Bologna-CERN-Florence-Genova-Moscow (LPI)-Paris VI-Santander-Valencia

Setting Up

WA59 Measurement of nucleon structure functions in horn focused ν and beams in BEBC filled with Neon

Aachen-Athens-Bari-Birmingham-Bonn-Brussels-CERN-London (I.C.)-Munich (MPI)-Oxford-Palaiseau-Rutherford-Saclay

Setting Up for 1980

WA60 Study of strangeonium and baryonium produced in K-p interactions using the Omega Prime spectrometer

Bari-Birmingham-CERN-Milan-Paris VI-Pavia

Completed 30.8.1979

WA61 Investigation of inelastic interactions of high energy hadrons in nuclear emulsions

Cairo Completed 3.8.1979

NA1 Measurement of the photoproduction of vector and scalar bosons

Frascati-Milan-Pisa-Rome Data Taking

NA2 Electromagnetic interactions of muons Annecy-CERN-Freiburg-Hamburg (DESY) Kiel-Lancaster-Liverpool-Oxford-Rutherford-Sheffield-Turin-Wupper-tal " "

NA3 Hadronic production of high pT leptons and hadrons CERN-Collège de France-Orsay-Palaiseau-Saclay

" "

NA4 Inclusive deep-inelastic muon scattering and search for multimuon events

Bologna-CERN-Dubna-Munich-Saclay " "

NA5 A study of hard hadron-hadron collisions with a streamer chamber vertex spectrometer and a calorimeter trigger

Bari-Cracow-Liverpool-Munich (MPI)-Nijmegen " "

NA6 Neutron elastic scattering at very small angles

Freiburg-Moscow (ITEP) " "

NA7 Measurement of the electromagnetic form factors of π and Κ mesons at the SPS London (W'fd.C.)-Southampton-Frascati-Milan-Pisa-Rome Preparation

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Exp. No.


NA8 Hadron elastic scattering at smail angles Clermont-Ferrand-Leningrad-Lyon-Uppsala Data Taking

NA9 Study of final states in deep inelastic lepton scattering by the addition of a vertex detector Aachen-Annecy-CERN-Freiburg-Hamburg (DESY+Univ.)-Kiel-Lancaster-Liverpool-Mons-Munich-(MPI)-Orsay-Oxford-Rutherford-Sheffield-Turin-Wuppertal

Preparation

NA10 High resolution study of the inclusive production of massive muon pairs by intensive pion beams

Palaiseau-Strasbourg-Zürich (ETH) Setting-Up for 1980

NA11 Measurement of charmed particle production in hadronic reactions

Amsterdam-Bristol-CERN-Cracow-Munich (MPI)-Oxford-Rutherford

Data Taking

NA12 Study of π-p interactions with neutral final states

Moscow(IHEP)-Brussels(IISN)-LAPP Preparation

NA13 Search for direct evidence for charm in hadronic interactions using a high-resolution bubble chamber

Brussels-CERN-Oxford-Padova-Rome-Rutherford-Trieste Completed 9.7.1979

NA14 Photoproduction at high energy and high intensity

CERN-London (IC)-Orsay-Saclay-Southampton Preparation

NA15 Search for charmed hadron production in π- nucleus interactions in nucl. emulsion

Bombay(Tata Inst.) Completed 3.8.1979

NA16 Study of hadronic production and the properties of new particles using LEBC-EHS Amsterdam-Brussels-CERN-Madrid-Mons-Nijmegen-Oxford-Padova-Paris

VI-Rome-Rutherford-Serpu-khov-Stockholm-Trieste-Vienna Setting-up

NA17 Momentum and angular correlations study in proton-nuclei jets at high energies using emulsion telescopes technique with and without magnetic field

Santander-Strasbourg-Lyon Preparation

NA18 Search for short-lived particles produced on nuclei with a heavy liquid mini bubble chamber

Bern-Munich (MPI) Preparation

NA19 Direct observation of beauty particles selected by muonic decay in emulsion

Bari-Brussels-CERN-Dublin-London (UC)-Milton Keynes-Rome-Torino

Preparation

NA20 Measurement of the yield of π±,Κ± in 400 GeV proton-baryllium collisions

CERN-Rutherford Data Taking

UA1 Α 4π solid angle detector for the SPS used as a collider at a c.m.energy of 540 GeV

Aachen-Annecy-Birmingham-CERN-London (QMC)-Paris (Coll. de France)-Riverside-Rome-Rutherford-Saclay-Vienna

In Prenaration

UA2 Study of interactions at 540 GeV c.m. energy Bern-CERN-Copenhagen-Orsay-Pavia-Saclay In Preparation

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Exp. No.


UA3 Search for magnetic monopoles at the colliding ring Annecy-CERN Preparation

UA4 Measurement of elastic scattering and of total cross-section at the CERN collider

Amsterdam-CERN-Genova-Naples-Pisa Preparation

UA5 Investigation of events at 540 GeV c.m. energy with a streamer chamber detection system

Bonn-Brussels-Cambridge-Stockholm Preparation

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ISR EXPERIMENTS ON THE FLOOR IN 1979 Exp. No.


R108 Study of high transverse momentum phenomena CERN-Columbia-Oxford-Rockefeller Completed 16.7.1979

R110 Study of high mass electron pairs and high transverse momentum phenomena CERN-Columbia-Oxford-Rockefeller Data Taking

R209 High mass muon pairs and associated hadrons Frascati-Harvard-MIT-Naples-Pisa-Bologna-CERN Data Taking

R415 Study of events with large-angle electrons in SEM Bologna-CERN Completed 31.5.1979

R416 Study of rare events at the SFM Annecy-CERN-Dortmund-Heidelberg-Karlsruhe-Paris (Coll.de France)-Warsaw

Data Taking

R501 Search for magnetic monopoles Annecy-CERN Data Taking

R607 Correlation between high pL mesons produced in pp collisions at the ISR Amsterdam-Louvain-Northwestern Data Taking

R806 Study of large transverse momentum phenomena Athens-BNL-CERN Data Taking

R807 Study of large transverse momentum phenomena CERM-BNL-Copenhagen-Lund-Rutherford Setting Up

In addition:

R211 Measurement of the total cross-section at ISR Ams terdam-Louvain-Northwestern Preparation

R703 Evaluation of a large streamer chamber detection system and a study of - pp differences at ISR energies

Bonn-Brussels-Cambridge-Stockholm Preparation

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PS EXPERIMENTS ON THE FLOOR IN 1979

Status Exp. No.

Experiment Collaboration

Completed 9.8.79

S153 Hunt for narrow baryon formation in π-p backw. elastic scattering

CERN-Paris Coll.de France-EP Palaiseau

Completed 21.12.78

S154 Strangeness exchange reaction on nuclei Heidelberg (MPI+Univ.)-CEN Saclay-Strasbourg

Waiting for beam

S157 High-precision measurement of the π-p total cross-section

CERN-Paris Coll.de France-EP Palaiseau

Data Taking S159 Strange dibaryon systems Rome-Saclay-Vanderbilt Testing S160 Measurement of A and R parameters in the

reaction π+p → Κ+Σ+ Edinburg-Rutherford-Westf. Coll. London

Waiting for beam

S161 Search for strongly bound states of the , and (NN...) states Basel-Karlsruhe-Stockholm-Strasbourg-Thessaloniki

Testing S162 Study of the structure of the exotic light produced at the PS nuclei

Orsay (C.S.N.S.M + CNRS)

Data Taking S163 Search for narrow baryonium states near the threshold Heidelberg (MPI+Univ)-Saclay CEN-Strasbourg

Data Taking S164 The influence of channelling on atomic and nuclear reaction yields

Aarhus-CERN-Strasbourg

Data Taking S165 Measurement of the Κ-p scattering length at threshold by observation of kaonic-hydrogen X-rays from a condensed target

Birmingham-Rutherford-Surrey

Preparation S166 Search for Σ hypernuclear states using the strangeness exchange reactions (Κ-,π-) and (Κ-,π+)

Heidelberg MPI+Univ.-Saclay CEN

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SC EXPERIMENTS ON THE FLOOR IN 1979

EXPERIMENT NUMBER EXPERIMENT COLLABORATION STATUS

ISOLDE ISOLDE Programme ISOLDE Data taking

SC50 Nuclear cross sections of cosmic ray interest ORSAY Data taking

SC63 Elastic scattering of μ ρ and μ d muonic atoms against protons and deuterons BOLOGNA-INFN Data taking

SC64 Tests for fast separations of nuclear reaction products GSI, DARMSTADT Data taking

SC65 Local magnetic fields in ferromagnetics studied by positive muon precession CERN-UPPSALA Data taking

SC68 Muonic chemistry in condensed matter PARMA UNIVERSITY Data taking

SC70 Studies of fission of heavy nuclei induced by muons CERN-DUBNA-OSLO

Completed 10/5-79

SC73 π backward scattering on nuclei AMSTERDAM-BIRMINGHAM-CERN-LJUBLJANA-OXFORD-TURIN Completed 29/7-79

SC74 Measurement of the population and lifetime of the 2s state in muonic hydrogen

PISA-INFN, PISA Completed 7/8-79

SC75 Search for π+π- and Κ+ mesons with the 3μ e beam at the CERN SC

CAGLIARI-STRASBOURG-TURIN Completed 8/4-79

SC76 Impurity trapping of positive muons in metals CERN-GENEVA UNIV.-JULICH-UPPSALA Data taking

SC77 Determination of the branching ratio for the decay π0 → e+e- AMSTERDAM-BIRMINGHAM-CAGLIARI-CERN-LJUBLJANA-OXFORD-TURIN Data taking

SC78 Radiobiological experiments using the SC 600 MeV neutron beam

CERN-ROME-MANCHESTER Completed 7/10-79

SC79 Studies of binary fission of light nuclei induced by 600 MeV protons

LUND-OSLO Completed 14/8-79

SC81 Formation and interaction of muonium in insulators and semiconductors

CERN-PARMA-UPPSALA Data taking

SC82 Muonium and muons in synthetic polymers CERN-LONDON (IMP. COLL.)-PARMA-RUTHERFORD LAB.

Data taking

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EXPERIMENTAL PHYSICS FACILITIES DIVISION

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EXPERIMENTAL PHYSICS FACILITIES DIVISION

1. ISR PROGRAMME

1.1 Split-field magnet (SFM) operation

Two collaborations carried out experiments using the split-field magnet detector during the year. The Bologna-CERN Collaboration carried out experiment R415, triggered on one or two electrons in the central region by means of atmospheric pressure Čerenkov counters and shower detectors, with the aim of studying the associated event topology. The Annecy (LAPP)-CERN-Paris (Collège de France)-Dortmund-Heidelberg-Warsaw Collaboration ran experiment R416, triggered on partially identified particles with high transverse momentum at a centre-of-mass angle of around 45o for studies of event topology and jet structure.

The detector operated without a single breakdown during all the ISR running time.

The off-line event reconstruction chain was progressively refined to yield a uniform reconstruction efficiency up to a charged multiplicity of 40.

Preparations for adapting the detector to ISR operation with have started.

1.2 Axial-field spectrometer (AFS)

The central detector of the AFS, used in experiment R807 (CERN-Copenhagen-Lund-Rutherford Collaboration), consists of two semi-cylindrical chambers of the bicycle-wheel type, used for tracking and energy loss (dE/dx) measurement. The first chamber has been wired, assembled and tested. In the summer shutdown it was mounted at the ISR for a trial run. On the basis of present delivery estimates for readout electronics, final commissioning is scheduled for the end of November. The second chamber has been wired and tested. Assembly is starting and commissioning scheduled for mid-December.

The mechanical design of the R807 uranium-scintillator calorimeter and the design of the optical read-out system have been finalized, the latter requiring a large number of tests with various configurations and materials. Most of the calorimeter components have been ordered and some delivered. To ensure reproducibility in the scintillator properties throughout production, samples were measured of each batch of material.

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The assembly of the so-called "copper catcher" calorimeter units is well advanced, while the manufacture of the main calorimeter units is suffering from a delay in the delivery of the plates in depleted uranium to be used as absorber metal. A number of copper catcher units have been tested in a PS beam, with very satisfactory results, and installations of these at the ISR has started and will continue as units are delivered (at present approximately four units per week).

2. SPS EXPERIMENTAL PROGRAMME

2.1 Beams and RF laboratory

2.1.1 S1 beam

The superconducting RF separator installed in the S1 beam line has now operated for more than 5000 hours, serving four experiments with separated kaon and antiproton beams. The superconducting deflectors have been continuously under vacuum since 1977 and so far no sign of degradation of quality factors or decrease of the deflecting fields has been observed.

2.1.2 S3 beam

The S3 radio-frequency separated beam has been used almost continuously during the year, either for BEBC experiments or for the testing and calibration of various experimental detectors. In particular the S3 beam (branch test) has been used for the calibration of the neutrino experiment WA18, with an enriched beam containing about 45% electrons at 20 GeV/c.

A variety of test beams has been provided for a small heavy liquid bubble chamber from Bern (BIBC), for different detectors preparing a new neutrino emulsion experiment by a group from Rome, and for a transition radiation device by an Aachen-Brookhaven-CERN-Moscow Collaboration.

Three experiments have been performed in BEBC: WA28 (K- at 110 GeV/c), WA27 (K+ at 70 GeV/c in hydrogen) and WA51 (π± at 30 GeV/c in neon).

2.1.3 Neutrino beams N1, N3 and beam dump

First of all in 1979 a beam dump experiment was performed, then the wide-band neutrino beam N1 was used, in a new version, in which the attempt was made to achieve the greatest possible flux at high energy. For this purpose, a new magnetic horn and an additional magnetic reflector were constructed and installed. The whole system worked very well, without serious faults.

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Hitherto the high general background level in the various detectors has limited the energy of the proton beam to between 330 and 350 GeV. The source of this background was investigated, and a method of shielding was found which allows the reduction of the background in the detectors to an acceptable level with primary proton energy as high as 450 GeV. This new shield consists of a toroidal magnet, 6 m in diameter and 10 m long, which focuses the muons on to a plug, 4 × 4.50 × 36 m3, located approximately 100 m from the magnet. The weight of the magnet is about 2200 tons and the plug consists of some 5400 tons of cast iron.

The complete system (new horn, new reflector and new shielding) was tested successfully in June and July. The improvements in neutrino flux as well as in background, at 400 GeV, were in good agreement with the computations.

After this run of the N1 beam, there was a change-over to the narrow-band beam N3, which has been working successfully since then.

2.1.4 RF laboratory

An 800 MHz system for stabilizing a high-intensity proton beam in the SPS by Landau damping is being prepared for installation in the accelerator. Development and design of the two 3.5 m long TM01 travelling wave cavities is complete.

Computer studies and tests on a model have established that the required specifications could be met most economically by a discloaded structure in the π/2 mode with the discs being as thin as is compatible with the mechanical and peak field limitations. Symmetrical couplers between this structure and the feeding wave-guide have been developed using a model; asymmetrical couplers perturb the axial field symmetry within the coupling cell and consequently a particle passing this cell would receive a small transverse kick.

Next, a full-size 1 m structure with two couplers and cooling circuits was built, in order to verify the feasibility of the chosen manufacturing techniques, a sequence of high-precision machining and brazing operations. After successful tests of this prototype, the manufacture of a first 3.5 m cavity with its couplers has been started. It should be finished in November 1979.

A study of the possibilities of lowering the cavity Q for the deflecting TEM11 mode by a distributed selective coupling system has been started, using a model, and is still under way.

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2.2 BEBC

After maintenance during the shutdown, BEBC was ready for cool-down for the 1979 runs on 26 February. In contrast to the runs in 1977 and 1978, when mostly neutrino pictures were taken, the chamber resumed with a pure hadron run. BEBC was filled with hydrogen and exposed to the radio-frequency separated beam S3; first K- at 110 GeV/c (experiment WA28) and then K+ at 70 GeV/c (experiment WA27). The external particle identifier EPI was used for both experiments, and BEBC was operated in the double-pulsing mode so that two pictures could be taken during each SPS cycle, the first one with a burst of protons of 220 GeV/c on a target installed at the start of the radio-frequency separated beam line, the second one only 2 seconds later with protons of 272 GeV/c. Operating BEBC at this fast rate causes problems. The most difficult one (with a hydrogen filling) is to avoid turbulences which produce optical distortions and could make the second photograph useless. After a week of testing and optimization, the photographs of he first and second expansions were of the same good quality with little distortion. It was thus possible to obtain 80 035 photographs for experiment WA28 and 123 538 for experiment WA27 during 510 hours of scheduled beam time.

During the Easter shutdown of the SPS, BEBC was emptied and refilled with a heavy neon-hydrogen mixture of 75 mol per cent neon. The beam dump experiment WA52 started on 20 April and finished successfully on 29 May. A hadron exposure (WA51) was made in parallel, BEBC being run in the double-pulsing mode during part of the time. 136 300 beam dump pictures and 21 200 pictures for WA51 (π± of 30 and 64 GeV/c) were taken. This rather low score was due to problems arising from a fire in the SPS power station and several breakdowns on the water cooling system of the dump target block.

The chamber behaved well throughout the Ne/H2 run and was then emptied and warmed up in order to prepare for the deuterium run of period 3.

On 10 June, it was full of liquid deuterium and ready to be expanded. Four days of technical trials established that the refrigerator using hydrogen would be able to feed efficiently the heat exchangers of the chamber at the much higher pressure required for 30.5 Κ (11 atm instead of 8 for H2 operation). Parasitic boiling however was more abundant and the only solution was to operate the chamber at the even higher temperature of 31.1 Κ where good tracks could be obtained with very little distortions.

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After period 3A (78 000 expansions in the single-pulsing mode at 10.8 s repetition interval (58 500 photographs of for WA25) an attempt was made to double-pulse the chamber with 4.6 s pulse separation. It looked acceptable when period 3B started; photographs with tracks (ν for WA25, Κ of 70 GeV/c for WA27) showed, however, distortions which it was possible to reduce but not to eliminate during two days of trials. Double-pulsing was therefore abandoned, and the quality of the ν photographs was again as good as before. The pause between periods 3B and 3C was used to try once again double-pulsing under improved conditions. Indeed distortions were much reduced but the quality of the double-pulse photographs was still less good than the single-pulse ones. After four days it was decided to drop the hadrons and to go back to single-pulsing, which immediately led to excellent photographs owing to the better understanding of the behaviour of the chamber with U£ obtained during all the trials.

The final score of the run was 186 000 ν, pictures for WA25 and 32 700 K+ pictures for WA27. The chamber made 371 000 expansions with D2, 79% of them during scheduled beam time. The picture-taking efficiency was very satisfactory at 75%. The quality of the photographs improved throughout the run, to reach an excellent level during period 3C.

The tritium contamination of the deuterium used is very low (T/D ratio less than 3×10-15) because the deuterium was obtained from a "pre-bomb" heavy water stock in the USA. This leads to less than 10 000 small parasitic bubbles created in the visible volume during the 10 ms preceding the flash. This number seems high, but it is equivalent to only 5 tracks of 3.7 m length with ~ 7 bubbles per centimetre. These parasitic bubbles disturb neither the photographs nor the behaviour of the chamber.

No losses of deuterium whatever occurred throughout the run or during transfers between the dewars and the chamber. This is of course very important because the deuterium is not only of excellent purity, but also very expensive, so even small losses had to be avoided. Vacuum pump exhausts, check valves and safety valves etc. were all connected to a gas holder via a special manifold in order to recuperate fully the smallest amounts of deuterium.

The deuterium run happened to be physics run No.13, a number which apparently had no malign influence on its outcome. The only problem was the failure to obtain excellent photographs in the double-pulsing mode. The basic reason is known: more parasitic bubbles are created and bring more heat into the vicinity of the fish-eyes. The heat exchanger on top of the chamber easily takes up this extra heat but not without increased mixing of cold and warm liquid and the resultant thermal turbulence. It is hoped that this situation can be improved, but more trials, and hence more time, will be needed.

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After a shutdown for maintenance during period 4, BEBC restarted in September, again filled with a heavy mixture of neon and hydrogen (75% mol % Ne). It is currently exposed to antineutrinos of 200 GeV/c from the narrow-band beam N3. 106 197 pictures had been taken by the end of October, and the run will continue until December.

2.2.1 External muon identifier (EMI)

This apparatus, which allows the user to identify muons coming from neutrino interactions in BEBC, has been in continuous use during 1979 and has performed very well, losing not more than 1% of machine time.

A prototype "picket fence" counter for BEBC has been built. One module consists of a proportional counter 2.2 m long, 100 mm wide and 16 mm thick. This module contains 24 counter tubes 8 mm in diameter, in parallel. Using a mixture of argon and carbon dioxide, the module efficiency is 99%. Two such modules have been installed inside the BEBC vacuum tank. Careful checks have shown no adverse effects resulting from BEBC expansions, and it seems that the magnetic field of the chamber does not change the performance of the modules.

The construction of 150 modules will start in December, and their installation is planned for the long SPS shutdown.

2.2.2 External particle identifier (EPI)

The BEBC external particle identifier, EPI, was used at the beginning of 1979 in the two BEBC hadronic experiments WA27 (K+ at 70 GeV/c) and WA28 (K- at 110 GeV/c). EPI identifies the particles by sampling their ionization in 128 cells. The sampling method allows the possibility of cutting the long tail of the Landau ionization distribution. Each cell consists of a wire chamber and the ionization is measured by the pulse height in the sensitive wire. EPI has proved to be a very reliable apparatus, behaving as expected; in particular, the resolution for the ionization was as good as 6% FWHM. Off-line analysis of the EPI data is still under way.

2.3 GARGAMELLE

During January, work continued to prepare the damaged chamber body for inspection. The epoxy coating on the inside was sand-blasted away, and the welded-on heat exchangers around the suspect zone of the crack in the bottom of the chamber were machined off. The external heat exchanger, symmetrically placed at the top of the chamber, was also removed. An overthickness of 2 mm was left on all bars remaining attached to the chamber, to facilitate examination of the welds.

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In February the chamber was taken to the repair factory and inspection and testing continued. Samples were cut from the region of the crack for metallurgical examination. It was established that the crack had its origin in the external fillet weld which attached the outer bar of the heat exchanger to the chamber body.

The remaining overthickness from the bars of the removed exchangers was ground away, and the external surface of the cylindrical section smoothed off for careful examination. This revealed a large number of apparently minor surface defects which would all require removal. It also brought to light a short but deep crack at the top of the chamber body, symmetrically opposite to the one at the bottom. This crack originated at the inside fillet weld of an outer bar of the top external heat exchanger, and could not have been detected without prior removal of the exchanger.

Appraisal of the additional work which had become necessary to continue the repair showed the programme to bring Gargamelle into operation again for 1980 to be gravely compromised. The chamber has been taken out of service.

When in October 1978 chamber operation ceased, the majority of the staff was temporarily assigned to other activities within the Division, leaving only a small team for work connected with the envisaged repairs. After the decision in the spring of 1979 to abandon repair work, a review was made of personnel requirements throughout the experimental programme, and by June the whole of the staff was re-deployed, mainly on EHS and major SPS collider and neutrino experiments.

Some of the instrumentation and control apparatus of Gargamelle was immediately useful for other activities, but the heavy equipment, such as the chamber body, compressors and magnet is still to be disposed of.

2.4 LEBC

LEBC (Lexan Bubble Chamber) is specially designed to search for associated charm production in hadronic interactions. Since the expected lifetime of charm mesons is between 10-12 and 10-13 s, high spatial resolution with a resolved bubble diameter of about 30 μm is desired, to identify charm decays (odd prongs of D± V0's for D0) within multiprong interaction vertices. According to the expected small charm production cross-section (between 10 ub and 100 μb) the chamber must be expanded more than 15 times during each 1 s SPS spill, to obtain a significant charm signal in a reasonable running time.

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The adopted solution is a cylindrical chamber, 20 cm in diameter and 4 cm deep, filled with 1 litre of liquid hydrogen and oriented with its axis horizontal and perpendicular to the beam. In order to provide a "clean" chamber, any seals and welds, which are common in conventional bubble chambers and cause parasitic boiling during the expansions, are avoided by gluing the Lexan parts of the chamber together. Lexan is a thermoplastic polycarbonate with good light transmission and suitable mechanical properties for use at liquid hydrogen temperatures, and has been used successfully in the past for the construction of the large track sensitive target (TST) for BEBC, run in 1978. Track sensitivity is achieved by expanding the chamber volume via a 5 mm thick membrane, which forms the rear flat end of the chamber cylinder, and is driven by an hydraulic expansion system. Scotchlite is glued on to the expansion membrane and particle tracks are photographed in bright field, through a 25 mm thick Lexan window which is glued, as is the front plate, on to the chamber body. The camera flash is triggered by counter logic, which selects beam interactions in the hydrogen in the chamber.

The proposal for this charm experiment (NA13) was approved on 1.11.1978 by the SPSC. First tracks from a γ source were seen in LEBC on 28.4.1979. This fast set-up was only achieved by close collaboration between the BEBC, Gargamelle and EHS groups who joined their efforts to build LEBC. During a test run in a 340 GeV negative pion beam (14.5. to 18.5.1979) about 30 000 pictures were taken. A production run in the same beam from 27.6. to 9.7.1979 resulted in 110 000 pictures. During this run, the chamber was cycled at 16, 32 and 40 Hz at a temperature of 29 K. The resolved bubble diameters ranged from 30 to 40 μm and the bubble density from 80 to 100 bubbles/cm.

By the beginning of September, about 20% of the pictures taken had been scanned and five clear double charm decays found with a background as low as 0.2 events. In the meantime LEBC has been moved downstream, where it will be combined with some EHS elements which will provide momentum analysis for the secondaries in a magnetic spectrometer behind the chamber. The first combined run is scheduled for November 1979.

2.5 Omega prime

During the 1978/1979 SPS shutdown the Omega spectrometer was improved to become the "Omega prime" system. The central spark chambers were replaced by multiwire proportional chambers.

Because of late deliveries of integrated circuits, the experiments WA55 (large-angle scattering of K+p and π+p), WA56 (baryonium search) and WA60 (study of strangeonium) used the initial configuration

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of forward chambers only. In October, the chambers surrounding the target were also installed and used by experiment WA49 (study of interactions).

In this final configuration, Omega prime allows the simultaneous detection and identification of many particles in the forward direction, as well as the measurement of wide-angle tracks around the target (vertex detection). The system performs as expected with respect to rate and multiparticle capability, two-track resolution and accuracy. The experimental teams using Omega prime made a big effort in performing five experiments in its first year, the last experiment being WA57 (high-mass vector meson photoproduction).

2.6 Expérience WA44

Proposée en août 1977, acceptée en décembre de la même année, construite et installée pendant l'année 1978, l'expérience WA44 (Collaboration CERN-Bologne-Frascati-INFN pour rechercher les quarks libres produits dans les interactions neutrinos-nucléons) a fonctionné durant toute l'année pendant les différentes périodes de faisceau neutrino. Il y a eu une période de production de neutrinos sur cible à absorption totale et trois périodes de dix jours de production de neutrinos à large bande: deux d'antineutrinos et une de neutrinos. 71 324 photographies ont été prises, durant ces différentes périodees, avec la chambre à avalanches AC 235 travaillant en mode avalanches. D'ici à la fin de l'année, des périodes et de ν en bande étroite sont prévues. L'ensemble de l'appareillage construit a fonctionné de façon très satisfaisante.

Une révison complète de l'équipement a été effectuée pendant la longue période d'arrêt estivale. Quelques défauts ont été corrigés et différentes améliorations ont été apportées, en particulier: modification de l'éclateur principal de la ligne de Blumlein en vue d'augmenter la stabilité de l'amplitude des impulsions à très haute tension (1% FWHM a été obtenu sur de longues périodes de temps), amélioration de l'étanchéité de la chambre et du contrôle du gaz, nettoyage complet du générateur de Marx. Les difficultés techniques les plus sérieuses rencontrées jusqu'à présent ont été celles relatives au fonctionnement haute tension défectueux des amplificateurs de lumière. Des modifications essentielles de l'alimentation haute tension des tubes sont en cours d'exécution.

L'analyse automatique des photographies ainsi que l'étude générale des données ont commencé. La mesure de l'ionisation de chaque trace et la recherche automatique des candidats quarks sont prévues. L'étude de la calibration de l'ionisation primaire en fonction du gaz, des conditions de la chambre, du temps et du type de particules a également commencé. Dans ce contexte, une Bessymatic équipée de photodiodes sera utilisée.

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3. FILM ANALYSIS

3.1 1969-1979: Ten years of LSDs

The two spiral leader devices (Lecteurs à Spirale Digitisée, LSD1 and LSD2) completed in September 1979 their tenth year of continuous data production in finishing the measurement of the 2 m hydrogen bubble chamber photographs of the K-p (8.25 GeV/c) experiment. This year 223 742 vertices (113 737 events) have been analysed.

Over their ten-year life the LSDs have treated more than 3 200 000 vertices (about 1 800 000 events), running for around 80 000 hours with very good efficiency. Their rather low operational cost and high measuring speed have certainly contributed to their success. Their history is closely related to the history of the CERN 2 m bubble chamber: more than 4 million pictures from this chamber have been treated, representing about 10% of its total output - and more than 2000 km of film scanned!

A large number of physics papers have resulted from experiments measured on the LSDs. Among the more remarkable contributions to bubble chamber physics can be mentioned those relative to the understanding of production mechanisms at intermediate energies as well as those referring to spectroscopy. In this latter field, very interesting results have been obtained, such as the observation and establishment of the properties of the δ, A1, C(Q1), Ε, D, f' and ω* mesons, the first evidence of the Ξ*1680, Ξ*1820, Ξ*2030 and recently of a very narrow resonance at 3.17 GeV, called the R hyperon.

3.2 ERASME/Bessymatic

In 1979 the principal work of the ERASME/Bessymatic facility was the analysis of two BEBC experiments: WA47, a neutrino experiment in a neon-hydrogen mixture, and WA27, K+p at 70 GeV/c. For WA47 about 1500 events were treated and for WA27 about 10 000. In addition, half of a new beam dump experiment (WA52, 70 000 pictures, 230 events) was analysed at CERN within six weeks. For experiment WA28, 12 000 pictures of Κ ρ interaction at 110 GeV/c have been scanned and the measurement of some 2000 events has been started. Help was given in connection with a BEBC neutrino experiment in which no CERN group is participating (ν and wide band in D2, WA25) by providing scanning tables and by measuring fiducials and a small number of events during data taking.

Bessymatic tables were also used to scan LEBC pictures and streamer chamber pictures from several different experiments.

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Test measurements for future EHS experiments indicated that the ERASME/Bessymatic system should be able to handle high-energy hadron events with good resolution, an excellent pass rate and reasonable speed.

No special hardware or software developments were required on ERASME for the continuing analysis of BEBC photographs. Development has, however, started for the future analysis of EHS film. A major addition has been made to the computing facilities supporting data production by the installation of a VAX 11/780 computer which will be devoted to offline treatment of the data.

Installation of seven Bessymatic tables with CAMAC electronics was completed and the tables are now being improved by the installation of photodiodes for automatic fiducial measurements and of electronics for driving ERASME-like displays. Additional high-magnification lenses (x 45) are being installed on the MILADY tables for scanning 50 mm film from LEBC and EHS.

4. SPS EXPERIMENTS IN PREPARATION

4.1 European hybrid spectrometer (EHS)

The EHS commissioning programme has been adapted to the SPS schedule for 1980. Effort is being concentrated on having most of the electronic detectors working in early 1980 for a "running-in experiment" before the SPS shutdown in June, whereas the installation and setting-up of the rapid-cycling bubble chamber RCBC will be undertaken from July onwards.

During the spring of 1979, the running-in experiment for EHS developed from a pure debugging and training exercise into a full physics experiment on short-lived particles, when the successful bubble chamber LEBC was incorporated into the provisionally reshuffled EHS spectrometer. In September this enterprise was approved as experiment NA16.

Construction of the EHS wire chambers is well advanced. Apart from a small trigger chamber, all EHS multiwire proportional chambers have been installed in the beam line and are now being debugged. Construction of the drift chambers is continuing at Amsterdam and Vienna. The first of three Austrian modules arrived at CERN in September and the first of three Dutch modules in October. Both were immediately installed in the beam where required for NA16, and are now being tested.

The two EHS photon detectors, the intermediate (IGD) and the downstream (FGD), have been assembled on their movable stages during the summer and are now being tested with electrons. They are currently being equipped with air conditioning for better gain stability and a laser system for stability monitoring.

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A small bending magnet was installed in August, just downstream of LEBC, and its field mapped in September. The re-installation of LEBC at 3.5 m downstream of the future centre of RCBC started at the end of September. The first beam particles were received in the EHS area on 18 October and were used for testing wire chambers and photon detectors. Two other beam periods are scheduled this year, in November and December, and will be used for setting up LEBC, the spectrometer and the photon detectors.

The ISIS (Identification of Secondaries by Ionization Sampling) model is being prepared in the SPS assembly hall with improved high tension and gas recirculation systems; it will be incorporated into the NA16 set-up early next year.

The superconducting RCBC magnet M1 is almost finished at Saclay. The first coil, which has already been successfully tested, will be installed at CERN at the end of November. The complete magnet is expected to be operational on the RCBC support frame from February 1980. Although it cannot be used with LEBC, it will be very useful for testing RCBC components in its stray field. In addition, the field of M1 must be mapped before the downsteam spectrometer can be installed.

Construction of RCBC is progressing at the Rutherford Laboratory. Many components are now well advanced, such as vacuum equipment, optical windows and the telecentric lenses. The machining and welding of the chamber body has been delayed owing to technical problems with critical elements (e.g. the beam windows) and owing to strikes. The first of the three RCBC cameras was working in July at 16 Hz. Two others are being prepared to serve initially as stereo cameras on LEBC. Gas handling equipment is being installed inside and outside EHN1.

4.2 Experiment NA10

The CERN-Ecole Polytechnique Palaiseau-ETH Zurich-Strasbourg Collaboration has nearly completed the construction of the equipment for experiment NA10, and started in October its installation in ECN3, the experimental cave of the North Area High Intensity Facility (NAHIF).

Apart from the large pulsed air-core toroidal magnet, which will be installed early next year, most of the components are now in place: the hadron absorber and the iron wall, three out of four multiwire proportional chambers built at Saclay and two out of four built at Zurich, two counter hodoscopes built at Ecole Polytechnique and two built at Strasbourg.

The electronics of the read-out system for 20 000 wires is now complete, as is the fast trigger logic which receives signals from some 800 photomultiplier tubes. The on-line data acquisition and reconstruction software is also in final stages of testing and debugging.

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With this initial installation it is intended to start the running-in of the experiment during the first SPS period next year. The full installation is expected to be available in March and it is hoped that some significant physics data will be obtained before the long SPS shutdown.

5. COLLIDER EXPERIMENTS

5.1 Expérience UA1

Dans le cadre de la collaboration pour l'expérience UA1, les responsabilités du CERN sont partagées entre les Divisions DD, EF et EP.

La Division EF se trouve principalement engagée dans les activités suivantes:

- construction mécanique du détecteur central;

- calorimétrisation et assemblage de l'aimant.

5.1.1 Construction mécanique du détecteur central

Le prototype de la chambre centrale est actuellement en cours de tests et a permis de vérifier la validité des caractéristiques essentielles du détecteur.

L'activité de construction proprement dite est maintenant engagée. Le premier des quatre éléments "avant" du détecteur est actuellement en train d'être équipé, le tissage de la chambre devant démarrer prochainement. Cet élément "avant" devrait être prêt mécaniquement d'ici à la fin de l'année pour être testé à partir du mois de janvier 1980.

Le programme de construction des autres éléments devrait permettre d'atteindre l'objectif fixé, à savoir que l'ensemble des six éléments du détecteur (quatre éléments "avant" et deux centraux) soit prêt et testé d'ici à l'automne 1980.

5.1.2 Calorimétrisation et pré-assemblage de l'aimant

Les 28 éléments constituant l'aimant (16 éléments en forme de C et 12 en forme de I, d'environ 52 tonnes chacun) sont calorimétrisés à l'aide de scintillateurs.

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Les différents elements "C" et "I" seront livrés en totalité d'ici à la fin de l'année 1979. Au début du mois de novembre, 12 éléments "C" et 3 éléments "I" ont déjà été livrés.

Les composants nécessaires pour la calorimétrisation: scintillateurs, guides de lumières et photomultiplicateurs essentiellement, sont préparés par les trois laboratoires anglais de la collaboration UA1 (Birmingham-Queen Mary College, London-Rutherford). Les premiers composants ont été livrés au CERN au courant du mois de septembre. L'installation de ces différents composants a démarré dans le hall de l'ancienne chambre à bulles de 2 m. Il est normalement prévu d'équiper quatre éléments par mois.

Parallèlement à cette activité de calorimétrisation, l'aimant de l'expérience UA1 sera pré-assemblé dans le même hall au fur et à mesure que les éléments calorimétrisés seront disponibles. Déjà les rails et les chariots sont installés. Les dipôles devraient être totalement assemblés à la fin du mois d'avril 1980. A partir du mois de mai, l'aimant sera alimenté et testé et la carte de champ magnétique sera établie. D'ici au mois de juin 1980, et selon l'état d'avancement des travaux de génie civil à l'intersection LSS5, l'aimant devrait être démonté, transporté par éléments puis installé définitivement dans l'intersection.

5.2 Experiment UA2

This experiment is being carried out by a collaboration of six institutes (Bern-CERN-Copenhagen-Orsay-Pavia-Saclay). It comprises essentially a vertex detector to measure charged secondaries, a calorimeter to measure particle energies and identify electrons and photons from their showers, and magnets providing momentum determination in the forward direction and around 90°.

Since the collaborating laboratories are providing a large number of detector components, CERN has taken the responsibility for the general assembly of the experiment, and for the construction of the calorimeter and the magnets. During the year the general design has been completed and orders have been placed for the major components. A prototype calorimeter unit has been fabricated and is being extensively tested at the SPS.

5.3 Experiment UA5

En ce qui concerne l'expérience UA5 dont le but est l'étude des événements à 540 GeV à l'aide de deux chambres à avalanches, les tests préliminaires sur les éléments de construction des chambres

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de haute tension et de l'optique sont en voie d'achèvement. La réalisation des deux chambres est en cours et la plupart des composants, tels que générateur de haute tension, objectifs, amplificateurs d'image, etc., sont commandés.

6. GENERAL ACTIVITIES IN CRYOGENICS

6.1 Low-temperature laboratory

Once again the laboratory has offered its facilities and technical help to several groups from both inside and outside CERN for the following experimental and test activities:

- development of superconducting RF accelerating cavities (EF and EP Divisions)

- evaluation trials on conductors for a large superconducting magnet for fusion research (CNEN Frascati)

- liquid helium heat transfer measurements (EP Division)

- properties of materials at low temperatures (ISR Division).

The laboratory's own activity in the field of production and application of wide superconducting Nb3Sn ribbon has now concentrated on the construction of a small persistent current dipole magnet for demonstration and long duration observation purposes. This work is well advanced.

6.2 West Area helium refrigeration

The refrigeration plant and controls of the Omega superconducting magnet have functioned for 5000 hours in 1979 and have satisfied all physics requirements.

The 1.8 Κ refrigerator for the superconducting RF separator was somewhat less reliable, covering only 83% of the beam time scheduled for experiments with particle separation.

When the separator is not in service, the two deflector structures are kept at a temperature of about 80 Κ by cooling with liquid nitrogen from transport dewars to avoid deterioration of their performance. This laborious procedure is being avoided by the installation of an automatically controlled cryogenerator and liquid buffer on each deflector. The first system is already in operation and the second will follow before the end of the year.

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6.3 North Area helium refrigeration

The North Area helium refrigeration system is finally complete after the successful acceptance tests of the last two of the six identical refrigeration/liquefaction plants (each producing 400 W at 4.4 Κ or 100 litres of liquid helium per hour) in February and March 1979. Also in March, the small helium gas refrigerator capable of 1000 W at 20 K, intended for cooling RCBC, was successfully tested and accepted as scheduled. The purification plant of the North Area helium recovery system was commissioned at the beginning of January.

The five plants serving as magnet refrigerators have now accumulated about 18 000 hours of satisfactory operation and the sixth plant used as a liquefier has supplied about 80 000 litres of liquid helium this year in transport dewars for experiments on the Prévessin site.

6.4 Central liquefier

Use of cryogenic fluids for experiments during the first 10 months of 1979 has been as follows:

liquid nitrogen 4 000 000 litres

liquid hydrogen 30 000 litres

liquid helium 120 000 litres.

This liquid helium was supplied mainly to users on the Meyrin site.

A project for the acquisition and installation of liquid hydrogen storage facilities has been approved. These facilities will be erected on the Prévessin site in 1980/1981.

7. LEP STUDIES

7.1 Superconducting cavities

The Experimental Physics Facilities Division is collaborating in research and development work on superconducting cavities for the LEP project (see the section concerning LEP in the report of the ISR Division). Three major lines of research are being pursued:

(1) A 500 MHz single-cell accelerating cavity made from niobium sheet material is under construction. This cavity, of the spherical

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type, has been fabricated by spinning and electron-beam welding. The cryostat and measuring system have been prepared in the EF Division cryogenics laboratory.

(2) In collaboration with a group from the University of Wuppertal, the performances of single-cell niobium cavities at 3 GHz have been assessed. Testing both sharp-cornered cylindrical and spherical cavities with accelerating fields up to about 10 MV/m has revealed no multipactoring. Cavities manufactured by different methods (spinning and deep drawing) and given different surface treatments (electropolishing and high-temperature annealing for some, chemical polishing for others) have shown no significant differences in values of QO (between 3 and 8 × 109) and in peak accelerating fields. Field limitations are found to be due either to small localized regions with reduced critical fields or to electron loading caused by non-resonant electrical phenomena. In the light of these results, spherical cavities are favoured at present, because they are easy to construct, to clean (for example using ultrasonic methods) and they have a higher value of shunt impedance and very good RF properties.

(3) A measurement programme on re-entrant 500 MHz cavities with removable lids is being carried out in collaboration with Wuppertal and Orsay, and in close contact with the ISR vacuum group which carries out measurement and diagnoses in connection with superconducting metal surfaces. The first studies will concentrate on the influence of different surface treatments on the secondary emission coefficient of electrons in the superconducting cavities.

In addition to the cavity programme, diagnostic methods are being developed and tested. An array of carbon resistors mounted around a cavity is used for temperature mapping and breakdown localization. Solid-state X-ray detectors inside the helium bath have been tested as a means of measuring the angular distribution and energy spectrum of X-rays generated by electrons produced inside the cavity.

An ultra-high vacuum furnace capable of annealing a small cavity at up to 1800oC is under construction and a new chemistry laboratory is being installed in co-operation with the Technical Services and Buildings Division. In this laboratory chemical treatment of large cavities and multicell 3 GHz cavities will be possible under safer working conditions.

Facilities for measuring niobium cavities of different size and geometry at liquid helium temperature have been set up, involving new cryostats, a pumping system and RF measuring units at different frequencies and RF power levels.

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7.2 Detector studies

Some small-scale studies are taking place in the field of particle detection and identification:

Ionization Sampling Detector (ISD): this detector is essentially a 64 cell drift chamber, with a drift length of 50 cm. It is possible to vary the pressure of the gas from 0.25 to 5 bars.

The ISD has been built in order to make accurate measurements of the energy losses (dE/dx) in various gases at different pressures. It is also intended to measure the influence of the drift length and of the angle between the field and the tracks. The ISD, now complete, will be tested during the last period of 1979.

High-density projection chamber: this detector tries to cope with the difficult experimental conditions for photon and electron measurements to be expected at LEP. The electromagnetic shower develops in a perforated block of high-density material. The holes effectively sample the ionization in the shower as charged particles drift lengthwise along the holes. Position, drift time and charge, detected on the surface, are a measure of the location and energy of the shower.

Primary cluster counting: the aim here is to identify particles by their energy loss, by counting the number of primary ionization clusters rather than by measuring the charge, with a view to reducing the dimensions of the detector needed.

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DATA HANDLING DIVISION

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DATA HANDLING DIVISION

1. INTRODUCTION

This year has seen a dramatic growth in the demand for communications with the central computer facility. Some 35 minicomputers, mostly data acquisition computers in SPS and ISR experiments, are now connected via CERNET and transfer on average 1 gigabit of information per day. CERNET is currently available over 162 hours per week. Over 400 terminals are now linked to INDEX, which has been doubled in capacity to satisfy the demand for computer ports. An additional time-division multiplexed link has been installed between the North Area and the Computer Centre, providing a total capacity for 52 terminals. A second communications processor was added to the IBM bringing the number of lines available to 80.

The IBM 3032 has been integrated with the IBM 370/168 since the end of January, and the number of jobs processed on the combined system has doubled this year to 16 000 per week. An IBM 3800 laser printer has been successfully introduced and is widely used both locally, and remotely via CERNET. Demand for computing on the CDC system continues to be extremely high. A CYBER 170-720 is on order to replace one of the ageing 6000 front-end computers. Performance of both the IBM and CDC systems has been very good.

A DEC VAX/780 computer has been installed to meet the increasing data handling requirements of the ERASME and Bessymatic systems. Both systems are now connected to CERNET.

The staff supporting data acquisition systems at CERN experiments have been combined into one group. Support is provided for some 40 experiments and an equal number of beam-line tests which use computers from the one-line computer pool. Standard software systems are maintained for data acquisition on Norsk Data, Digital Equipment and Hewlet Packard computers. Work has started, to provide fast direct links between minicomputers of different manufacturers, using CERNET hardware and protocols based on those of CERNET. Common libraries are being compiled across the three supported minicomputers.

The Divsion provides off-line programming support for a number of experiments at the SPS and ISR. Work has started on programs to analyse data from collider experiments. During this year, the Division has been heavily involved in the preparation of various publications and exhibitions commemorating CERN's 25th anniversary.

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2. COMPUTER CENTRE

2.1 The CDC system

The demand for computing on the CDC system continues to be extremely high, placing a heavy load on the ageing front-end 5000 series computers, which have experienced a number of difficult hardware problems. A CYBER 170-720, which is to be rented to replace the 6400, should help this situation. Nevertheless the overall performance of the system remained excellent; the average availability continued to be more than 95%, whilst the average user CPU utilization on the 7600 increased to over 118 hours per week, with one spectacular week of 149.5 hours accounted to user jobs. The stability of the 7600 software was a major contributor to this performance.

Two additional 819 high-capacity disks have been installed on the 7600 bringing the total to eight, and trials are being made with Control Data's new high-density tape drives. Following detailed comparisons of the operating systems NOS/BE and NOS, effort is now being concentrated on the possibility of a conversion from SCOPE 3.4.3 to NOS/BE. A new tape management program has been put into service. An INTERCOM Users Guide has been published as well as a revised 7600 Users Guide.

2.2 The IBM system

Since the end of January, the 370/168 and 3032 have been operating in a highly integrated system, where both processors have direct acess to all of the users'disk files, the 3850 mass storage system, the communications processors, the tape units and the job input/output queues.

Normally the 3032 is used for the terminal service and the 370/168 for production jobs. The system is scheduled so that at least one processor is always available. After initial difficulties, the system is working well, with up to some 16 000 jobs per week now being processed. The workload has been variable in terms of user CPU utilization with an average of 165 hours per week for the two machines and peaks of well over 200 hours. Overall availability has been good, with figures of over 99% for the terminal service and 98.6% for the production service.

Recently a new version of the job entry system has been installed; this permits networking between processors, local or otherwise. The first use of this is for a link to the CISI centre at Saclay.

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A second communications processor was added in March to increase the number of WYLBUR lines to 80 and to improve availability. In April the 3800 high-speed laser printer was installed. Its capacity, coupled with its flexibility for changing character sets, has enabled the Computer Centre to retire three conventional line printers. Many users have realized the potential of this printer for producing high-quality documents, and special character sets and page layouts have been designed for these applications.

The file migration system (hierarchial storage manager) has now been in use for over a year and is proving very successful in ensuring the effective use of disk space.

Major improvements have been made to the IBM accounting and resource control system, in particular to incorporate the 3032, and to take into consideration all of the major resources used in the calculation of the cost of a job.

2.3 Data communications

There are now 35 minicomputers around the site using CERNET, the majority of which are data acquisition computers in SPS and ISR experiments. CERNET operation is now regularly scheduled for 163 hours per week and the average weekly availability of the central services as seen by the CERNET end-user has been 98%. CERNET itself achieved 99.6% average weekly availability. Towards the end of the period, the typical daily average for the traffic through CERNET showed some 2000-3000 logical links being opened to transfer 1 gigabit of information.

The replacement of the FOCUS system has been completed with the connection of HP 21MX data acquisition computers to CERNET. Access to and development of centralized facilities for software development, file storage and archiving facilities for the PDP-11, NORD-10, HP 21MX minicomputers has been completed on the IBM system, thus replacing and extending similar services on the CII 10070 which was taken out of service in December 1978.

Extensive software has been introduced for the control and monitoring of the network configuration and its status. Comprehensive and easily assimilated graphical displays of the status are available to the computer operators on a colour display. Associated refinements such as remote loading of network nodes have made the operation tasks easier with resulting improvement in network availability.

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Three Modcomp Classic computers have been brought into operation. These will provide increased throughput over the existing Modcomp 11/45 machines. The Classics are replacing the most heavily loaded II/45s in the Computer Centre, two of which are now being installed as nodes for the West Experimental Area.

Access by CERNET to the IBM 3032 has been improved by the use of a dedicated channel connection. File transfers between the IBM and CDC central system are now made entirely via CERNET, thus replacing the slower TIELINE system. New facilities completed include a software "bridge" to enable terminals on computers connected to CERNET to use the IBM WYLBUR file-editing system, remote job entry and output retrieval via CERNET on both the IBM and the CDC central computers. A graphics station using a NORD-10 computer has been connected via CERNET to provide fast turn-around for graphical output from the IBM and CDC computers.

The CERNET data link interfaces have been improved and now transmit at speeds up to 5Mbits/s. For nodes with many links connected, a new simpler and more economic mechanical mounting system for the transmission equipment is being introduced. A prototype link switching unit has been designed and constructed; this will allow switching under program control of a group of links between two adjacent nodes in order to provide uninterrupted service to some users if one of the nodes in the pair is down. The CERNET CAMAC link has been adopted as a standard for interconnection between different types of minicomputer in experiments at CERN. It is intended that this equipment will be manufactured by industry.

Owing to the large number of different host computers connected to INDEX, saturation of the available computer ports was reached early this year. In June and September the two PACXs in the Computer Centre were replaced by PACXs of double capacity. The old PACXs will be used in regions where there is dense clustering of terminals and minicomputer hosts.

An additional time-division multiplexed link has been installed between the North Area and the Computer Centre. The number of terminals connected to INDEX now exceeds 400, including several connections with outside institutes, e.g. the Rutherford Laboratory, Saclay and LAPP, Annecy. VDU terminals allowing full 132 character lines to be displayed are being installed for evaluation.

For the STELLA experiment in high-speed transmission via satellite, five of the seven computer interface modules for interfacing to the earth stations have been constructed. Those for Pisa, Rutherford and CERN have been tested on site. The NORD-10 computer for the earth station at CERN is installed, and installation of the antenna plus associated microwave and digital control equipment should be completed by the end of the year.

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2.4 General

A first version of the PL-11 compiler has been installed on the DEC VAX-11/780 computer and effort is continuing to adapt the language to the specific features of this computer. The BCPL compiler for HP 21MX computers running under the RTE-IV operating system has been completed, and work is continuing on a VAX-11/780 implementation. A PASCAL cross-compiler and interpreter for the TMS 9900 microprocessor are under development. The program for maintaining libraries in the new universal load module format (CUFOM) and for link editing from such a library has been made available.

New mathematical consultancy work for the Experimental Physics Division included the numerical calculation of the structure function F3 in QCD, the minimization of waste when cutting trapezoids for scintillators, and the calculation of a special filter for three-dimensional image reconstruction for a positron camera with limited angular acceptance. A non-linear boundary value problem on a semi-infinite interval has been solved for the SPS Division. The Program Library manuals were entirely revised and reprinted to represent the versions on both IBM and CDC computers. Work is well advanced on the computer readable version of the manuals.

Two Tektronix 4081 intelligent graphics terminals have been installed for finite element modelling (FEM) work in particular. A CERN graphics guide has been produced.

Continuing assistance has been given to users throughout CERN maintaining altogether about 80 data bases on the central computers. Three High-Energy Reaction Analysis (HERA) reports have been produced, in collaboration with the Experimental Physics Division, using the IBM 3800 laser printer. Olivetti DE730 intelligent terminals have been installed in the Data Handling, Health and Safety and Technical Services and Buildings Divisions to ease the problem of data entry. Communications software has been written to allow them to be operated on-line to the central computers as required.

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3. DATA PROCESSING

3.1 ERASME and Bessymatic

A VAX-11/780 computer was installed in August to alleviate data handling bottlenecks at these facilities. Software for very fast file transfer between this computer and the DEC System-10 has been implemented, and work is in progress to connect the machine to CERNET using the standard CAMAC interface. The ERASME and Bessymatic systems are already connected to CERNET. Studies and tests of pattern recognition techniques were made for the EHS facility, including the running-in experiment NA16.

3.2 European hybrid spectrometer (EHS)

Collaboration continues on the implementation of the hardware and software required for the data acquisition and control systems of the European hybrid spectrometer. The two NORD-10 computers are being used for concurrent commissioning of several detectors to be used for the first tests of the NA16 experiment. A real-time data base for equipment monitoring and control has been completed.

Exhaustive tests on the use of a RETICON diode to provide a fast optical read-out of the rapid-cycling bubble chamber, for trigger purposes, were very encouraging.

3.3 Support for computers on-line to experiments

At the start of 1979, a new group, the On-line Computing Support Group, was set up, bringing together the staff working to support data acquisition and control systems at experiments. Support is provided at various levels for the on-line computer pool of about 120 computers, which serve some 40 experiments and an equal number of beam-line tests. Standard software systems are maintained for data acquisition on Norsk Data, Digital Equipment and Hewlett Packard computers. At the beginning of March the staff involved in these activities were moved together, and the program development computers were installed in the Computer Centre.

Work has started to adapt the PDP-11-based data acquisition system to the different constraints imposed by high rates and small events at the synchro-cyclotron, and also to prepare for the transfer to the DEC VAX-11/780.

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Hardware and software installation was carried out on two major NORD-10/NORD-50 systems for the NA10 and UA1 experiments. As mentioned earlier, CERNET hardware will be used to provide fast direct links between minicomputers of different manufacturers. The protocol will follow closely that of CERNET also. An attempt is also being made to provide common libraries across the three supported minicomputers. The ESONE CAMAC calls and the PLOT-10 graphics package are already implemented; the next area to be tackled is that of histogramming. The Division was involved in studies of the data-handling requirements at LEP, in the context of the ECFA studies, and in the investigations of the use of FASTBUS for experiments at CERN.

Twenty units of the CAVIAR micropressor-based equipment test system, which has both IEEE-488 and CAMAC interfaces, are being manufactured by industry.

Major progress has been made in unifying the budgeting, administration and maintenance of all supported minicomputers. Details of some 5000 items that comprise the 120 configurations are being entered into standard data base system (IMAGE) on the Hewlett Packard development computer. Five editions of a new publication, the CERN Online Computer Newsletter, have been published.

3.4 Off-line programming support

The Division has continued to provide off-line programming support for a number of experiments at the SPS and at the ISR. New experiments which are being assisted at the SPS include UA2 (for the proton-antiproton project), NA9 and NA14.

The analysis program (TRIDENT) for Omega Prime has been used for experiments WA55, WA56, WA60 and will shortly be used for WA57.

For WA18 the data of the narrow-band beam, wide-band beam, and beam dump runs of last year have been analysed, yielding significant results.

Similarly, a significant part of the data taken by NA3 has been analysed extremely rapidly and has led to several publications. At WA1 the calibration programs for scintillators and drift chambers have been transferred from the CDC system to the local NORD-50 as they are heavy users of computer time.

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3.5 Development of special processors

A hard-wired processor was used for real time event selection by experiment WA7. The trigger rate was increased by some 30%, whereas the recording rate was reduced by a factor of two. The data contained 2.5 times more elastic events than in previous similar runs.

A larger instruction memory and some extra interfaces were added to the microprogrammable processor ESOP. Commissioning of ten ESOP processors for use in experiments NA11, R807 and with the EHS was started. At NA11, tests of the results of ESOP calculations on real data from wire chambers were completed satisfactorily.

The development of the prototype of a fast ECL processor MICE (MICrogrammable filtering "Engine") using the Motorola 10800 bit-slice has been completed. It emulates the PDP-11 basic instruction set and executes instructions three times as fast as the most powerful model of the PDP-11 range. Higher speeds can be achieved via microprogramming and special hardware for particular algorithms. The hardware has been simulated using an Instruction Set Processor (ISP) system developed at Carnegie-Mellon University. A high-level microprogramming language, using a meta-assembler,was also implemented. These two software tools allowed the micro-code for the PDP-11 emulation to be written and tested in a few weeks. Checkout was completed in six weeks, as the simulation was almost 100% correct.

A wire-wrapped version of the 168-E processor is now available for evaluation. A prototype interface to a PDP-11 has been built and software is available to load programs from the IBM via CERNET. Work has started to attach the 168-E to a large secondary level memory so that big programs can be overlaid.

4. ELECTRONICS WORKSHOP

The workload on the Divisional electronics workshop has increased over the last year, due to the large amount of equipment constructed in small series. Close to 10 000 hours of wiring were done by commercial firms under service contracts, representing over 50% of the total load. A growing amount of printed circuit board lay out is also being done by outside firms.

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5. SCIENTIFIC INFORMATION AND PUBLICATIONS

The library collection of periodicals was rearranged and some shelves were added to provide extension for forthcoming issues during the next two to three years.

The computer-based cataloguing system now includes the file of CERN publications, generated by updating the corresponding preprint records. The weekly preprints and reports accessions list has been made available for viewing on all CERN computer terminals at the same time as the documents are put on display in the Central Library.

The compilation of a small bibliographic data base covering selected literature on the use of energy in agriculture was started to provide information for a study on the utilization of waste heat.

The systematic collection of documents relevant to CERN's history was started as a basis for the Organization's historical archives.

In addition to its customary duties throughout the year in providing for the production of CERN documents and activities in the public relations field, the Publications Group played an extensive role in the events to mark the 25th anniversary of CERN. Versions of the standard visitors' literature in four languages were prepared in a more attractive four-colour format as well as a brochure reviewing 25 years of CERN's history and a special issue of the CERN COURIER.

An anniversary album of photographs was produced, and dedicated copies were presented to staff having twenty-five years of service at CERN. Special attention was also given to exhibitions. A Technology Exhibition covering some 600 m2 was set up in a newly erected hall with the collaboration of representatives of each Division. A popular exhibition was set up at the Balexert shopping centre to make contact with the host Geneva community. It was seen by many thousands of people and resulted in many requests for guided tours of CERN. An exhibition was also organized on the Prévessin site for the Jour d'accueil.

Following studies of the needs of the Text Processing and Document Reproduction Sections, extensions to the photocomposition system were ordered, and a new offset press acquired. This re-equipping should ease production problems in the future.

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II. ACCELERATOR DIVISIONS

- Proton Synchrotron Division - Intersecting Storage Rings Division - SPS Division

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PROTON SYNCHROTRON DIVISION

A. Proton Synchrotron

B. Synchro-cyclotron

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PROTON SYNCHROTRON DIVISION

INTRODUCTION

At the beginning of 1979 the PS reached a further milestone on the road to rejuvenation. Besides the new Linac, it has acquired a new system of poleface windings and new rectifiers for the main magnet power supply. After a short period of adaptation, and with the help of sophisticated methods for dealing with instabilities caused by collective effects, the denser beam from the new Linac produced a marked increase in the usable output of high energy protons. However, the full potential has not yet been realized and, with better beam observation techniques on their way and the operating staff gaining experience on the new equipment, a significant further improvement in performance may be anticipated in the coming months.

Besides steadily increasing output, we have become accustomed to a steadily falling breakdown rate. However, with the various new projects on hand, the staff are more than fully occupied, and cutbacks have had to be made in preventive maintenance. In an effort to forestall any serious decline in reliability, an analysis is being made of the strengths and weaknesses of the various components making up the PS complex, so that available resources may be deployed to the best advantage. This takes on added importance in the context of antiproton acceleration, where a single cycle represents hours of production and cooling time.

The SC has continued to perform well. Following its highly successful helium-ion programme, the acceleration of quadruply-charged carbon ions was achieved on schedule at the end of August. After a short running-in period, beams of 3 - 4 × 1011 ions per second were being produced, with an energy of 85 Mev/nucleon. Neon ions were also accelerated, and there are good prospects for the ions of a number of other light elements. Notwithstanding the continuing development programme, it has proved possible to transfer a certain number of staff to PS projects in urgent need of manpower.

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A. PROTON SYNCHROTRON

1. THE PHYSICS PROGRAMME

1.1 Operation

From the last three weeks of 1978 onwards, the new Linac has been in routine operation as injector to the PS accelerators for most of their running time. It provides a 50 MeV beam of higher current than its predecessor, and also of significantly better quality - denser, and with a stable energy spread throughout the pulse duration. Although it worked well from the beginning, a fair amount of effort was required from both experts and operating crews before the real benefits began to show up. With the help of new methods of suppressing instabilities in the Booster and PS, previous records for accelerated beam intensities shortly began to fall, and the present peak reached in the PS is 1.6 × 1013 protons per pulse. A double-batch transfer of nearly 3 × 1013 protons to the SPS enabled that machine to reach a new maximum of 2.1 × 1013 at 200 GeV/c.

After the long shutdown at the beginning of 1979 the three accelerators were back in normal operation in a remarkably short time, despite an unusually large amount of newly-instailed equipment. This was achieved by a carefully planned series of pre-start tests and checks, as well as a lot of effort put in by all the staff concerned.

Entry into regular service of the new Linac was not the only innovation for 1979 operation. New methods of combating instabilities were introduced, for example beam-loading compensation for the RF cavities throughout the acceleration period and feedback to damp certain longitudinal instabilities. Moreover, in response to requests for additional time for experimental physics, the standard running period between maintenance stops was lengthened from five to seven weeks. The feelings of apprehension with which this change was greeted were to some extent justified; repairs to equipment not sufficiently essential to stop the accelerators had to wait a longer time, often increasing the difficulties of operation. A study is being made of the problems of reliability and maintenance arising from the extended running period.

Supercycles of 9.6, 10.8 and 12 seconds were all in use at one time or another, depending upon SPS operation. Generally, two batches of 10 GeV/c protons at high intensity were sent to the SPS, followed by three or four cycles supplying experiments on the PS floor at 24 GeV/c and/or the ISR at one of their standard momenta (11, 15, 22 or 26 GeV/c). Upon request, accelerated beam intensity for the cycles supplying PS experiments was increased from the 4 - 4.5 × 1012 protons per pulse of 1978 to 6 - 7 × 1012; the various improvements in beam quality mentioned above made this possible whilst still retaining a reasonable overall efficiency.

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When the ISR was not running, or was using protons at a momentum lower than 24 GeV/c, the burst shared between slow ejection and the test beam target could be lengthened by some 30%. For short periods, one of the 24/26 GeV/c cycles was taken over to supply "ICE" with 46 MeV protons for tests of electron cooling, or for other special purposes, and towards the end of the period under review for tests of the newly-installed experiment studying "exotic light nuclei".

The overall fault rate has remained gratifyingly low, although it shows a small increase on the preceding year. More important breakdowns involved the old (IBM 1800) controls computer, leakage in the heat exchanger of a transformer feeding the main magnet power supply, and both of the fast internal dumping targets. Certain faults only affected some users, for example the continuous transfer system supplying the SPS (currently carrying a heavy load, but shortly to be reinforced), and electrostatic separators for secondary beams situated inside the primary beam enclosures. Operating statistics for the period under review are shown in the table below.

Scheduled operation : 6174 h Experimental physics : 5461 h - time lost due to breakdowns : 195.1 h (3.6%) Machine development and start-up : 713 h

Distribution of accelerated protons (units of 1016) :

SPS ISR External Dump East Hall Primary Beams Target

01 ICE Internal Dump TOTAL SPS ISR External Dump Slow extr.n Fast extr.n

Target 01 ICE Internal

Dump TOTAL

4112.8 73.2 508.2 3146.5 13.4 160.4 77.0 183.2 8274.7

1.2 Experimental areas

The slow-ejected primary beam in the East Hall, e15, has three branches in which four targets supply five or six experiments running simultaneously. During the shutdown at the beginning of the year, some modifications were made to the layout. Two new secondary beams were constructed; from the North branch an enriched π+ beam (m16) was provided for experiment S160 using the Rutherford magnetic spectrometer for the measurement of A and R parameters in the reaction π+ + p → Σ+ + K+. At the end of the central branch a new low-momentum (0.6 - 1.3 GeV/c) antiproton beam (k25) replaced the former Κ- beam; its target uses the primary protons left (~ 60%) after an earlier target supplying another beam (k23). The new beam is being used by experiment S163 - a search for

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narrow baryonium states - with the Saclay spectrometer SPES II; at 800 MeV/c it yields 6.2 × 103 per 1012 incident protons for a momentum spread of ± 1%. In autumn the experimental zones of P17 (π's with high momentum resolution) and k23 were modified to accept experiments S164 ("channelling") and S165 (K-p scattering length observed by X-rays from kaonic hydrogen) respectively. This year, the three branches of the primary beam are using a higher intensity, namely 5 - 6 × 1012 protons per pulse (with the greater part, ~ 3 - 3.5 × 1012, in the central branch) at 24 GeV/c. Tests are being made on the feasibility of reducing the momentum and increasing the spill time; this is of particular interest for future low-momentum Κ and beam users.

A new shielding enclosure has been constructed for the beam employing fast ejection from straight-section 58 (e18). Early in the year this was used to test a target intended for antiproton production (for the Accumulator) in a high-intensity proton beam (> 1013 per pulse); the opportunity was taken to check the shielding efficiency. Later the enclosure was modified to accommodate experiment S162 (study of the structure of exotic light nuclei) which began testing in October.

Extraction from straight-section 74 and the beam transport line supplying the "ICE" experiment was successfully operated down to 46 MeV for studies of electron cooling. During the summer the beam line was modified so that electron production from 18 GeV/c protons on a target could be measured, with a view to future experiments on "relativistic" electron cooling.

In the South Hall, beam d31 was used for tests of the improved version of the "channelling" experiment prior to the latter's installation in beam p17. Other beams in this area were extensively employed for equipment tests.

1.3 Experimental area equipment

A major effort was required to keep the six electrostatic separators installed in East Hall beams in good running order. Almost inevitably, with the longer running periods, some time was lost by individual experiments when repairs had to await a scheduled stop.

A batch of new target assemblies has been ordered for use in primary proton beams, since the higher intensities now in common use make it essential to have spares available. The target heads will be enclosed in a different quality of quartz which is expected to retain a higher degree of transparency after irradiation.

The secondary emission chambers used to monitor slow-extracted beams have been under continuous development for a number of years, and their performance in operation shows a high degree of stability. An instrument of similar construction, but filled with argon and used as an ionization chamber, has proved popular with experimenters in SPS North

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Hall secondary beams, mainly because of its ability to measure particle fluxes over the wide range of 106 to 1011 per second.

The mobile remote-controlled manipulator ("MANTIS" - see previous reports) has been successfully used in the highly radioactive SPS neutrino cave; firstly, to remove a survey column in an ambient field of 3 - 5 rem/hour, and secondly to exchange a number of valves and flowmeters in confined spaces behind magnets and shielding. None of these devices had been designed with remote handling in view. "MANTIS" will shortly become even more independent with motorized wheels and an automatically-tracking steering system.

2. CURRENT TECHNICAL DEVELOPMENT

2.1 Linear accelerators

Following its successful trials in December 1978, the new Linac entered full-time service as injector to CERN's high energy machines when operation recommenced in February this year. It has displayed creditable reliability so far, with much of the 1.1% down-time in the first eight months being accounted for by inexperience in diagnosis on the new systems.

The original Linac is ordinarily maintained on "cold" standby i.e. under vacuum and with the pre-injector column partially formed for high tension. It was once more in operation during June and July whilst further work was carried out on the new machine, and it is also being used in development work on the production of a pure alpha-particle beam, which has been requested for experiments at the ISR.

During the shutdown at the beginning of the year and in the June/July period the new Linac installation was essentially completed, and a significant increase in beam brightness was obtained, leading to more efficient transfer to the Booster. Currently, the machine is being tuned up to get it running at the peak design intensity of ~ 150 mA. Prototype units, still in use in various places, have now been replaced by the final versions. A new fast stabilizer has been installed on the pre-injector EHT, designed around a single tube to enhance reliability and ease of maintenance. The 50 MeV beam transport system has been provided with more diagnostic equipment and better shielding against stray fields. On the controls side there has been continued expansion in software possibilities; in particular, the two computers now work in a back-up configuration.

A new type of ion source is on test. Called the "multi-dipole" or "bucket" source, it has a colder gas discharge than the duoplasmatron model used at present and hence produces a less noisy beam.

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2.2 Booster synchrotron

The Booster has continued to operate reliably and to furnish beams of high intensity and density. With a 120 mA beam from the new Linac, up to 1.8 × 1013 protons per pulse are routinely accelerated to 800 MeV in cycles destined for SPS injection. Concentrating the twenty bunches into ten, as will be required for antiproton production, gives the high value of ~ 5 × 1010 protons/metre for the critical parameter of mean linear density. Cycles not supplying the PS continue to be extensively employed for the observation and optimization of performance during operation and for machine studies; in the near future they will also be used by an experimental team carrying out exploratory studies of target designs for a planned neutron source. These "parasitic" cycles have recently been provided with new facilities, including pulse-to-pulse programming of the top energy and (in one ring) the RF accelerating voltage.

The new 6.6 MVA reactive power compensator and the additional filter elements required for fast cycling have been successfully put into operation, and most of the other items for this project are scheduled for delivery by the end of the year. In the context of antiproton production, the double septum magnet and other beam-handling elements for the ten-bunch mode of operation are being prepared, together with their power supplies and the beam observation equipment. After overcoming some difficulties encountered by the manufacturers, production of pick-up electrodes, deflectors, amplifiers and associated equipment for the eight transverse-instability damping systems is now making satisfactory progress. Assembly of all the spare septum magnets should be completed by the end of the year.

Most of the specific interfaces between PSB equipment and the new standard CAMAC modules have been made and installed, and - where appropriate - checked out with a micro-processor-assisted stand-alone test facility. All details of PSB hardware and functional data required for conversion to NORD computer control have been supplied to the project group.

Machine studies have been largely directed towards adaptation to the higher intensity and different characteristics of the beam provided by the new Linac. A system to damp longitudinal in-phase oscillations has been developed and brought into service, and dynamic compensation of the stop-band 3QV = 16 is in regular operation; the search for the best working region in the QH/QV diagram continues. Other studies concern possibilities of reducing particle density in a controlled fashion and means of compensating for the effects of beam loading. For some of this work sophisticated methods of measurement are being developed, for instance observation of beam response to transverse and longitudinal excitation, and Schottky scans either in the frequency domain or in the time domain with subsequent fast Fourier transform.

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2.3 Main proton synchrotron

Installation of new poleface windings on the main magnet has now been completed. During the shutdown at the beginning of the year the second half of the 404 sheets of windings were mounted on the magnet units, end-block clamping and vacuum chamber modifications being carried out at the same time. New cabling was laid to connect the 808 half-circuits in eight branches to the reconstructed central distribution switchboard, through which they can be connected in series or parallel to the appropriate power supplies according to operational requirements; it also permits speedy replacement of a faulty supply. Each half-circuit is fitted with a plug-in unit for passive compensation of the vacuum chamber eddy-current effect. Two new transformers have also been provided to compensate the "F" and "D" groups (on the focussing and defocus-sing halves of the magnet units respectively) against induced voltages at injection.

This work entailed dismounting more than half of the 600-metre ring vacuum chamber and the fitting of something over five hundred new metallic seals. The completion of so heavy a programme in good time for thorough testing before the accelerators started up reflects great credit upon the efforts of the staff concerned with planning and carrying it out. They included helpers from other Divisions, particularly ISR and SB. The new poleface winding system functioned correctly from the very beginning, and so far three of the new power supplies have been commissioned (for the "F" and "D" groups and the figure-of-eight loop).

Another major change during the annual shutdown was the replacement of the mercury arc rectifiers of the main magnet power supply, which have supplied more than a hundred million pulses since 1968. They have now been supplanted by a thyristor rectifier system; the whole operation, from dismantling to commissioning, was accomplished in less than two months. Among other benefits, there will be a substantial saving of electrical power, amounting to some 2 GWh in an average year (160 000 Swiss francs at present prices).

The new 800 MeV injection kicker was installed at the beginning of the year to replace the previous overloaded unit. Not only does the new model have capacity in reserve, but it is considerably more versatile, in order to cope with special modes of injection anticipated in the near future. Although there was no time to go through a full programme of checks and tests, little difficulty was encountered in getting it properly working, and its performance in operation has been most satisfactory.

In connection with the project for multi-batch SPS injection, one doublet and one triplet of the gamma-transition-jump system have been rearranged to free space for the installation of a "fast bumper" in straight-section 77. A kick-enhancement quadrupole has been added in straight-section 73.

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The performance of the power supplies for the sextupoles used for corrections at low energy has been improved, and filters inserted in the circuit to suppress radio-frequency pick-up coming from the circulating beam.

The radio-frequency accelerating system is currently undergoing substantial alterations in order to cope with antiproton production and acceleration. Major modifications are being carried out on the low-level part (beam control), and a third cavity-tuning system will be installed. Final installation of the 200 MHz RF, comprising eight cavities and the associated equipment, was completed during the long shutdown, and a high degree of reliability has now been attained.

2.4 Ejection and targets

The full-aperture kicker system is being re-structured in order to cope with the multiple tasks it will have to perform in the near future. Besides fast ejection as at present to PS experimental areas and the ISR, it will play a part in three- and five-batch transfer to the SPS, five-bunch ejection to the AA, antiproton transfer to the SPS and ISR, and high-density proton beam ejection for the collision mode in the SPS. Design of the new equipment is completed, prototype tests have been carried out on one module, and orders will be placed by the end of the year.

Two targets for beam measurements, driven by fast-acting resonant mechanisms, have been installed and calibrated with respect to the former models before these were removed.

2.5 Computer control

Four breakdowns in the IBM 1800 hardware, although not resulting in the loss of very much proton production time, served to underline the importance of the new controls project. A number of improvements have been incorporated in existing programs. All the equipment in the Central Building used for low energy corrections can now be started and stopped through the computer, which simplifies application of safety regulations. Further developments have taken place in programs for the autonomous function generators, used to control many important machine elements. A complete set of acquisition and control for the new injection kickers has been introduced, incorporating special modes of injection used for machine studies.

3. FURTHER DEVELOPMENT AND FUTURE PLANS

3.1 Performance developments in the PS

Beam supplied to the SPS is first bunched at 200 MHz on the 10 GeV/c "flat top". With all eight radio-frequency cavities working, a trapping efficiency of more than 95% was expected; however, the value

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measured turned out to be only 85 - 90%. A careful analysis of the debunched beam before recapture revealed that the discrepancy was due to longitudinal instabilities at the fifth, sixth and seventh harmonics of the revolution frequency. It looks as if these instabilities are provoked by the coupling impedance presented by the vacuum chamber connecting flanges, and preparations are being made to improve the situation by fitting radio-frequency bypasses. Double-batch injection, with 1.4 - 1.5 × 1013 protons transferred for each PS cycle, has enabled the SPS to reach peak intensities in excess of 2 × 1013 protons per pulse; triple-batch transfer has been tried, but in present conditions it does not enable the SPS to reach a higher intensity.

In the interest of further increasing PS intensity, work continues on compensation of resonances, optimization of the "working point" and suppression of instabilities. A maximum of 1.6 × 1013 protons per pulse has been obtained. A feedback loop for the active damping of mode 1 longitudinal dipolar* instabilities is now in operation, and another new feedback loop is being used to eliminate quadrupolar longitudinal instabilities at low energies (from injection onwards). The performance of the system installed to counteract the effect of beam loading on the RF accelerating cavities has undergone further improvement, and it now functions throughout the period of acceleration. A transverse feedback system designed to counter multi-turn instabilities over the whole energy range is under development.

Development continues of the technique for concentrating the usual twenty PS bunches into five, with high linear density, for future antiproton production. The first stage of ten bunches, carried out where beams from the four Booster rings are brought together, has now achieved an intensity of 1.1 × 1013 protons per pulse. After determining that the second stage would best be done by longitudinal combination in pairs in the PS at top momentum (26 GeV/c), several study sessions finally produced fast ejection of 9.5 × 1012 protons in the space of a quarter of the PS circumference. Further development will be directed towards obtaining higher intensities.

Protons have been decelerated in the PS right down to 46 MeV, for electron cooling studies in "ICE". The work on deceleration techniques has helped in planning the low energy antiproton stretcher ring, "LEAR". In the same context, a technique of stochastic extraction is being studied, in the hope of obtaining spill times as long as ten or twenty minutes. It has been found, as predicted by theory, that the extraction duty factor can be appreciably improved by the influence of a noise-modulated 200 MHz signal on the debunched beam; the spill waveform becomes much less sensitive to the various sources of ripple. Other possibilities of satisfying LEAR's requirements are being investigated theoretically.

* "Dipolar" etc. and the mode number are form and frequency parameters for the oscillations excited.

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Tests have been made of a method of measuring intensity distribution in beams by using secondary emission in a thin carbon fibre. They were sufficiently promising to permit the design of a prototype system for further studies.

Various projected modes of operation from 1980 onwards will require much lower intensities in the machines than is customary at present, and so several sessions have been devoted to testing and optimizing monitoring equipment for low level beams.

3.2 Development of the control system

During the year, the basic systems software (manufacturer's operating system and network software) has been running reliably. Subroutine libraries and language support have been added, and at the time of writing all necessary network and real-time facilities are accessible from NODAL and PASCAL as well as from low-level language. The capacity of the program development computer has been increased. Basic microprocessor software is operational, and a stand-alone microprocessor NODAL with floppy disc access has been delivered by a software house.

The first new main operator console with all its hardware and software has become operational and was made available for application software tests in July. Three further main operator consoles are being assembled; the body of one more, the security console, has been delivered. The interactive software package for the high resolution refreshed graphics, produced under contract, is due in January. Hardware for the local mobile console network has been received and installed in parallel with the first CAMAC serial loops. For the microcomputer-assisted and CAMAC-based mobile autonomous test station for process hardware, the above-mentioned NODAL software package will be used and the first units should be available at the end of the year.

Contracts were placed early this year for production and testout of CAMAC process interface modules and the analogue signal observation system for the PSB, AA and Antiproton Transfer Lines. Production deliveries started in August. The prototyping of the microprocessor-based auxiliary crate controller, a joint venture with SPS, has been terminated and series deliveries from industry are due before the end of the year. This module will be used throughout the system for fast, simple and repetitive tasks, e.g. pulse-to-pulse beam property adjustment and buffering fast data burst from beam measurement equipment. A supporting structure for acceptance tests and maintenance of standard interface material has been set up. This involves diagnostic software for each module and for the transfer system (serial CAMAC), a maintenance computer and a temperature-cycled testing facility. The final detailed layout of the standard interface will be frozen by the end of this year and its installation has started. The conversion and installation of specific process electronics is in an advanced state and combined tests with first production standard interface equipment are going on.

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The definition of the application software from the operations point of view has been followed by a conceptual design phase in which a description of the proposed software product has been submitted to users in the form of a catalogue of specifications, in itself also the beginning of comprehensive documentation. On the basis of the amended product description, production of the application-specific modules has been under way since spring of this year. These are interactive modules, process control modules, equipment modules and CAMAC interface modules and real-time tasks in microprocessors; a number have been delivered for various test phases of the AA equipment. In parallel a hierarchical skeleton of executive modules has been defined and produced, which has the task of linking, coordinating and arbitrating the activities of the application-specific modules, from the interactive modules at the consoles down to the real-time tasks in the twenty-five microcomputers in CAMAC. A complete first version of this skeleton is in an advanced stage, and it will be tested with a representative spectrum of specific application modules before the end of the year.

The definition of the operational aspects for the second conversion package, due to come into operation early in 1982, has been started.

3.3 Multi-batch filling for the SPS

The "fast bumpers" currently in use for continuous transfer to the SPS have been modified, and a second emittance-reduction dipole added in the beam line. This has been done in order to improve the operational reliability of extraction over four and five turns from the PS for triple and double-batch SPS injection.

For future extraction modes over two and three turns, the new "fast bumpers" have already been installed in the machine, and the rest of the associated equipment - pulse generators, cabling, switchgear and controls - is nearly ready. The extraction septum magnet has been delayed by late delivery of laminations, but construction of its power supply is well advanced.

3.4 Antiproton accumulator

The detailed design of all the equipment required for the initial beam tests in the second half of 1980 is now complete. All major orders have been placed with European industry, and most components are being delivered in accordance with the desired schedule, but some important items are being seriously delayed by an industrial dispute.

It was found possible to recoup the lost time caused by the unusually wet weather conditions last winter, so that construction of the semi-underground hall required to house the ring is now complete. Marking-out by the survey team and installation of equipment has begun.

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Design of the target area, where the full PS intensity will be used to produce antiprotons, is now complete. This has involved close collaboration with those concerned in EF, EP, HS, ISR, SB and SPS Divisions in order to ensure maximum reliability together with the requirement that those exchanging or repairing components should receive as little radiation dose as possible.

The fast kicker magnets for injection and extraction of the antiprotons are being progressively built, tested at high voltage, baked-out to 1000oC and installed in their ultra-high-vacuum tanks. One half of the injection kicker magnets has been completed and tested satisfactorily under high vacuum, and installation of their pulse generators in the AA hall is progressing rapidly.

Many aspects of the stochastic cooling systems have been further studied. Theoretical and computational optimization of the numerous parameters has been finalized and combined with the characteristics measured on prototype components.

The radio-frequency system, which is needed to stack each pre-cooled injected pulse and for unstacking from the dense part of the stack, consists of an old PS RF cavity which has been successfully modified for ultra-high vacuum and a special power amplifier, now under construction.

The computer controls for the AA ring are progressing well. Following the installation of serial CAMAC links to the AA control computer, much of the hardware is being tested via its definitive interface equipment using the software which will be needed during the run-ning-in phase.

To separate each new pulse of antiprotons from the stack during injection and pre-cooling, the injection kickers and the ferrite pick-ups and kickers of the pre-cooling system must be equipped with movable shutters. Just before the injection of a new pulse of , these shutters must be opened briefly to allow the stacking of the previous pre-cooled pulse. An extensive programme of tests is under way to determine the most reliable choice for each component: electric or hydraulic motors, drive mechanisms, bellows, pivots inside the ultra-high vacuum, and cooling of the ferrite. Adequate solutions are now in hand for all aspects, but it is expected that the programme of development and testing will need to continue well after the first operation of the ring as an antiproton source.

The magnets for the AA ring comprise two types of dipoles and two of quadrupoles. The first of the narrow type of quadrupole has been delivered by the manufacturers and found to be satisfactory. The wide-aperture quadrupole, which was based on three-dimensional computations and magnetic measurements on a CERN-built prototype, is progressing satisfactorily. Unfortunately, both types of dipole magnetic circuits are now seriously behind schedule, since in addition to an extended period of tooling fabrication the manufacture has been stopped by a protracted

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industrial dispute. This has already seriously eroded the time available at CERN for the assembly, magnetic measurements, shimming, vacuum chamber installation, leak checking, magnet installation and alignment. A considerable effort is being made to reduce the time required to a minimum, to preserve as much testing and running time for the AA ring as possible prior to it being needed as a source of antiprotons for the SPS in the second half of 1981.

3.5 Antiproton acceleration

Building work on the return loop tunnel - through which anti-protons from the AA are sent back to the PS - is finished, and the various services are being installed. Design of the beam transport and observation system has been completed, and such components as could not be found elsewhere in CERN are on order.

A septum magnet for antiproton extraction (in the reverse direction from straight-section 58) is under construction. Owing to the configuration of accelerator components in this region, the bending angle required is larger than usual. A scheme has been worked out to reduce the effect of the greater momentum spread (of the ) on beam dimensions, and the required components are on order. The beam transport line linking up the PS with the transfer tunnels leading to the SPS and the ISR has been completely specified and the necessary equipment ordered.

The problems of antiproton acceleration in the PS will be studied by using a proton beam simulating the characteristics of the beam. This is being prepared, together with the requisite hardware to cope with very low intensities, and it is expected that tests will begin before the end of the year.

3.6 "LEAR"

LEAR - "low energy antiproton ring" - has been conceived in order to provide experiments with a steady, high and uncontaminated flux of low energy antiprotons (0.1 to 2 GeV/c). It will be located in the PS South Experimental Hall, and supplied with , from the Antiproton Accumulator, decelerated in the PS. Studies reached a "conceptual design" stage early in the year, and have since been further elaborated. After a "Workshop" held at Karlsruhe in March, which again emphasized the very considerable interest of many European physicists in this experimental field, the PSC Committee and the Research Board gave their approval in principle to the construction of the facility. All aspects are now being reviewed in detail, and a design study report will be submitted in the spring of 1980. Necessary arrangements for the execution of the project are being prepared, and contact with the intending users has been formalized. At the most optimistic estimate, the facility could be available in the second half of 1982.

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Β. SYNCHRO-CYCLOTRON

1. OPERATION

During November, December and the first three weeks of January internal beam intensity was limited to 2.5 μΑ in order to avoid overloading the standby rotary capacitor Rotco 1. Repair of the motor bearings of the unit in normal service (Rotco 2) took longer than anticipated owing to an elusive vacuum leak, which eventually turned out to be due to an unsuspected hole plugged with Araldite during the original construction. When Rotco 2 was back in action beam current returned to its normal value of around 4 μA.

Operation continued to be reliable. Thirteen experiments using the proton beam have been taking data, as well as one using helium ions (3He++). In addition there is extensive employment of the ISOLDE facility, representing about one third of the whole SC experimental programme.

The annual long shutdown started at the beginning of March and lasted for three weeks. Besides routine maintenance, the cooling system of the main oil diffusion pump baffles was improved, and preparations made for the later installation of a more versatile version of the probe target (used for intensity measurement at different radii and the irradiation of samples). One week in June was devoted to trying out the new ion source, and first tests of carbon ion (12C4+) acceleration and extraction were carried out during two weeks in July and August.

Between November 1st, 1978, and October 31st, 1979, the functional division of SC machine time was as follows (figures in hours):

Machine time for Experimental Physics : 6133 (334 with 3He++) One user during : 3469 Two users during : 2664 Parasitic use : 2116

Technical development : 575 (453 for 12C4+)

Unscheduled stops : 279 (4.2%) Breakdowns : 226 Ion source filament changes : 53

Scheduled stops : 1773 Beam changes, maintenance and cooling : 711

Shutdown and official holidays : 1062

TOTAL 8760

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2. DEVELOPMENT

Most of the available effort has been devoted to the project for the acceleration of carbon ions (12C4+) and the design and construction of two beams for experiments with ions.

A new ion source has been constructed since the production of multiply-charged ions requires a much higher arc power than the proton source could provide. The filaments are made entirely of tungsten, and have lasted for six to eight hours during tests; work is in progress to find a means of lengthening filament lifetime.

The frequency modulation required in the SC for ion acceleration depends upon the charge-to-mass ratio. For 3He++ it is from 20.2 to 13.9 MHz, i.e. considerably lower than the 30.3 to 16.7 MHz shift for proton acceleration. The change is made by inserting a transmission line between the Rotco (rotary capacitor) and the Dee (accelerating electrode). The line consists of an inner conductor and a vessel serving as both outer conductor and vacuum tank, and it was found that by using different forms of inner conductor the characteristic impedance could be changed to give the frequency ranges required by a variety of ions.

It is necessary to properly match the radio-frequency components, namely, generator, Rotco, transmission line and Dee. This entailed the construction of a new RF generator, and some electrical modifications to Rotco 1 which upgraded its performance to the same level as that of Rotco 2. Both units should now be capable of running at 20 kV with a 1/1 duty factor, i.e. pulsing the RF on every cycle instead of one out of two. Average beam intensity would be doubled, but this will only be done in practice when use of the higher intensity can be fully justified, in the interest of keeping down radioactivity and hence personal radiation doses.

On August 29th a 1 2C + + beam was extracted for the first time. Subsequently, the source settings were optimized, and eventually stable beams of 3 - 4 × 1011 ions per second were obtained. Beam properties seemed to be much the same as for protons, and transport to the ISOLDE target gave a good transmission coefficient.

To examine the potential of the new ion source, production of other ions was tried, and results were most encouraging. A beam of 1 5N 5 +

ions was extracted; beams of 22Ne7+, 20Ne6+, 1 9F 6 + and 1 6 0 5 + were detected internally, but could not be extracted since no time was available to change the frequency range appropriately.

An experiment carried out on neutron production and shielding with the carbon ion beam has confirmed the design of the two enclosures for experiments currently being built. Construction of hardware for the ion beams is well advanced and installation will be completed by the end of the year. Four experiments are being prepared, in addition to those planned for ISOLDE.

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INTERSECTING STORAGE RINGS DIVISION

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INTERSECTING STORAGE RINGS DIVISION

1. INTRODUCTION

Following the decision to make economies in the experimental programme at the ISR, the number of planned running hours was reduced from 4886 in 1978 to some 4000 this year. Similarly development of the storage rings has been reduced in comparison with previous years and is now limited to that required directly to meet the requests of the experimental teams and to minor operational improvements. However, full advantage has been taken of the additional time made available for shutdown work in order to complete equipment installations and improvements, especially to the vacuum system, and these have permitted the proton beam currents to be increased. By the end of October the machine had achieved 2907 hours of operation of which 2002 were devoted to physics, the remainder to machine start up, development and stacking. The physics experiments have required operation mainly at 31 and 22 GeV and at both energies it has been found possible to increase the luminosity so that 4.8 × 10 cm-2 s-1 is available in the presently installed low-beta intersection at 31 GeV and a little more at 22 GeV.

Despite the reduction in running hours interest in ISR physics is certainly not decreasing as can be seen from the large inventory of experiments presently installed or in preparation. Two experiments, R108 (study of high transverse momentum phenomena) and R415 (study of events with large-angle electrons at the SFM) have been completed whilst three, R209 (high-mass muon pairs and associated hadrons), R607 (correlations between high PL mesons) and R806 (study of large transverse momentum phenomena) will finish taking data by the end of the year. Three further experiments, R110 (large-acceptance search for electron pairs), R416 (study of rare events) and R501 (search for magnetic monopoles) will continue taking data into next year. Following completion of the Open Axial-Field Magnet installation in intersection 8, installation work for experiment R807 (a study of large transverse momentum phenomena) has been carried out in every available shutdown whilst construction of the magnets and ancillary equipment for the superconducting low-beta insertion is progressing satisfactorily, aiming at installation in this intersection late next summer. Preparations for experiments R608 (large-X hadron physics and correlations) and R703T (evaluation of a large streamer chamber detection system and a study of pp-differences) are well advanced and they will be installed next January and summer respectively. Recently approved experiment R210

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(a precise measurement of the total cross-section) and R211 (a measurement of the total cross-section and small—angle scattering) are also expected to be ready by the summer and work has started on their layout in the intersection.

With an eye on ISR's immediate future a considerable amount of effort was made available for the Antiproton Accumulator project, especially with regard to the design, construction and installation of vacuum, RF, power supply, beam detection and magnet systems as described in the PS Division part of this report. In January this year the project to store antiprotons in the ISR was approved and since completion is planned for January 1981 the highest priority was given to design work and to ordering of equipment. The major item, construction of the transfer tunnel TT6, started in May but had several setbacks and a very special effort will be required if the schedule is to be maintained. On the other hand, the supply of magnets, cables, vacuum components and power supplies is not expected to pose serious problems.

The design study recommended at last year's LEP Summer Study of an electron-positron machine with a circumference of 30 km, an energy greater than 85 GeV and a luminosity of 1032 cm-2 s-1 was completed on schedule. The report, Design Study of a 22 to 130 GeV e+e- Colliding Beam Machine, known as the "Pink Book" (CERN-ISR/LEP/79-33), was published in August this year. This work involved major engineering studies of systems and components, together with the development of novel techniques for the construction of magnets, the RF system and vacuum chamber. So far the report has been presented to the Scientific Policy Committee and ECFA LEP Working Groups, both of which have given it a favourable reception. In view of the importance of superconducting RF cavities in extending the energy range of LEP, the collaboration with KfK, Karlsruhe and DESY, Hamburg has continued while additional studies have started in the EF and ISR Divisions in conjunction with the universities of Genoa, Paris XI-Orsay and Wuppertal.

2. THE STORAGE RINGS PHYSICS PROGRAMME

2.1 Operation

The operation of the ISR started on 8 March, after a nine-week scheduled machine stop to install the Open Axial-Field Magnet (OAFM), together with a new vacuum chamber in intersection 8 and, in both rings, additional collimators and higher-harmonic RF cavities. The planned reduction in the number of hours of running this year permitted machine operation to be interrupted in August and September to install new experimental equipment in intersections 1 and 8 and to improve the vacuum in intersection 2. Many other improvements were also carried out in both machine shutdowns but in spite of the many changes machine operation was resumed quickly and successfully after each shutdown by following carefully planned cold check-out and start-up procedures.

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During the first part of the year, the ISR operated at 31.4 GeV and the machine's performance was again improved; a maximum initial luminosity of 2.3 × 10 3 1 cm-2 s-1 in a normal intersection and an integrated luminosity of 4 × 1036 cm-2 being recorded. The OAFM was put into operation in this period and has since been used during physics running.

The physics experiments required a few 15 GeV runs in June and then mainly 22 GeV until the end of October. At 22 GeV the best initial luminosity was just a little higher than for 31.4 GeV and the machine was always operated with the low-beta section in intersection 1 powered, providing a local increase in luminosity by a factor 2.1 at 31.4 GeV and by 2.3 at other energies.

In general, the machine operated very well, while improvements in diagnostics and in procedures such as careful demagnetization and automatic space charge compensation during stacking led to greater efficiency and better reproducibility. Completion of the collimation scheme to control particle losses during stacking has resulted in the radiation background being simultaneously reduced in all intersections. As stacked currents increased, the continuing effort to improve the vacuum conditions was crowned with single beam record currents of 50.8 A in ring 1 and 49.2 A in ring 2.

To the end of October, the ISR had been in operation for 2907 hours, of which 473 hours were needed for machine start-up and development, 432 hours for filling the rings while 2002 hours were devoted to physics. Of the last figure, 86 hours were used for beam and collimator adjustments, beam clean-ups etc., thus providing 1916 hours of effective data-taking time, the running conditions being summarized in Table 1. Of the scheduled operating time 320 hours were lost owing to perturbations on the 18 kV power line (77 hours), non-availability of the PS (35 hours) and faults and problems with the ISR (208 hours).

Table 1 - ISR Physics Running Conditions in 1979

Max. luminosity × 10 3 0 cm - 2s - 1

Machine Energy GeV

Stable Beam Time (hours)

normal intersection

low-beta intersection

15 112 7.6 17.5 22 908 26.8 61.6 26 29 23 52.9 31 867 23 48.3

(adjustments) 86

2002

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2.2 Completed experiments

Two ISR experiments have been completed so far this year and three more are expected to complete their data-taking in December.

Experiment R108 (study of high transverse momentum phenomena) finished taking data in July 1979. This experiment had been installed in intersection 1 with the superconducting solenoid in 1975 and had taken data steadily since then. Reliability problems with the cryogenic plant for the solenoid continued at the beginning of this year but, after a very detailed revision, the plant has run continuously since May. When experiment R108 stopped to make way for its successor R110, all the lead-glass shower counters were removed and calibrated at the PS. Although many results are already published, data analysis is continuing.

One of the experiments using the Split-Field Magnet Detector, experiment R415 (study of events with large-angle electrons at the SFM) continued to run for the first two periods of the year and completed its data collection phase in June. During the last few weeks of running, the external particle identifiers of the SFM were complemented with the addition of an aerogel Čerenkov counter placed near 90O to the beams. Early analysis has been directed towards a charm search.

Experiments R209, R607 and R806 which are expected to finish taking data at the end of this year are mentioned in the following section.

2.3 Running experiments

In this year's summer shutdown, experiment R110 (large-acceptance search for electron pairs) was installed in intersection 1 although the proposal was only approved in March. The experiment, a development of R108, required a modified vacuum chamber to increase transparence and angular acceptance, the addition of lead-scintillator shower counters inside the solenoid and a rearrangement of the inner detector. The R108 vacuum chamber had four internal supporting bars which obscured the acceptance of the new detectors. A completely new external supporting structure was designed and built to hold the vacuum chamber from the solenoid itself and a new central chamber constructed without the internal bars. This chamber was installed early in the shutdown to allow time for the four new shower counters weighing over 1 ton each to be introduced into the solenoid using a special rail and support system designed and built by the ISR Division. Modifications were made to the solenoid end caps to allow the passage of the light guides for the shower counters and for the supporting system for the accompanying photo-multipliers. The installation was completed as planned and the experiment started setting up in October. It is expected to commence taking data in November.

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In intersection 2, experiment R209 (high-mass muon pairs and associated hadrons) has taken data throughout the year but a large fraction of the detectors were removed in July to allow a vacuum bakeout for machine improvement purposes. The experiment was remounted with modified shielding and, in the first period after the shutdown, was able to continue to collect muon-pair data at 22 GeV beam energy to investigate scaling.

At the SFM, experiment R416 (study of rare events) mounted a modified detector during the summer shutdown, which included the addition of forward Čerenkov counters. These should greatly enhance its capabilities for a charm search, as one such counter used in an earlier SFM experiment (R407/408) enabled a charmed baryon signal to be extracted from the data.

Experiment R501 (search for magnetic monopoles) continues to expose its kapton detector inside the vacuum chamber in the small solenoid magnet in intersection 5.

The double-arm magnetic spectrometer of experiment R607 (correlations between high PL mesons) has steadily accumulated data throughout the year, with most of its running time at √s = 44 GeV occurring in the autumn. The experiment is expected to complete data-taking at the end of the year.

In intersection 8, two experiments have been in operation. The 300 t OAFM, together with a new highly transparent "flatfish" type vacuum chamber were installed for experiment R807 (a study of large transverse momentum phenomena) as planned in January. Commissioning of the magnet and field mapping of the very large useful field volume were performed in situ. The magnetic field was found to correspond well to that predicted by computation, as did the elastic behaviour of the device under the influence of the large magnetic forces. Compensation of the effect of the OAFM on the circulating beams was optimized, and the system became available for use in physics runs in the first period.

Installation of the detectors of the experiment started in February and has continued in every available machine shutdown throughout the year, including the installation of about 2000 cables providing more than 20 000 signal channels. The particle identification arm consisting of a prototype drift chamber, a high-pressure Čerenkov counter of 40 m3 volume operating at 3 atm, an array of 18 atmospheric-pressure Čerenkov counters and 36 m2 of proportional chambers, is almost complete. The large size of the detectors in comparison with the dimensions of the intersection hall made their installation particularly complex and in the case of the 13 t support for the atmospheric-pressure Čerenkov counters required the design and mounting of special lifting devices. The detectors are all mounted on motorized chariots on a complex system of rails to allow rapid access to the central detectors and vacuum chamber. The cables are mounted on special mobile cable trays which move with the detectors. A comprehensive gas detection system has been installed to give early warning of inflammable gases leaking from the various

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detectors. One half of the final drift chamber was installed at the end of the summer shutdown on the outer side of the interaction region together with several copper calorimeters. Installation of the uranium-plate calorimeters is not now expected to take place until next year although all of the supporting structure and many of the cables are already in place.

Extensive modifications were carried out in the counting room at intersection 8 to provide adequate accommodation for the electronics and gas control systems of the detectors. The liquid argon calorimeters of experiment R806 (study of large transverse momentum phenomena) were remounted after the installation of the OAFM, on the outside of the intersection, in order to complete a measurement of direct single-photon production. Modifications to the calorimeter support and liquid argon system were necessary to make the experiment compatible with the R807 installations. The experiment has already published results on the production of direct single photons and since the summer, has run in collaboration with R807 to study particle multiplicities in correlation with single photons and π o.

2.4 Preparations for new experiments

Work is currently in progress on the installation of four new experiments and on the construction of the components of the superconducting high-luminosity insertion, all of which are planned to be installed in the ISR next year.

Experiment R608 (large-X hadron physics and correlations) is expected to be installed in the January 1980 shutdown. A pit will be excavated in intersection 6 to accommodate the detectors and the large-aperture septum magnet which has been designed in the ISR Division. Orders have been placed for the copper coils and steel yoke of this 30 t, 0.25 Tm magnet and the assembly, testing and mapping of the magnetic field are expected to be completed before the end of this year. A 1:5 scale model of the magnet has been used to help in the design of the comprehensive magnetic shielding needed to protect the ISR beams from the stray field. The trumpet-shaped vacuum chamber for this experiment is of a new design and is presently being assembled following successful testing of the 65 cm diameter, 0.3 mm thick stainless steel window. The large volume of the chamber has been loaded with damping resistors to avoid any disturbance of the ISR beams. Much work remains to be completed, including RF and vacuum measurements but it is expected to be ready for installation in January. Designs are in progress or completed for many of the mechanical supports and rail systems for the wire chambers, hodoscopes and Čerenkov counters which make up the particle detection system of the experiment. In addition to the usual installation in the ISR, assistance will be provided for the assembly of the large gas Čerenkov counters and a shower counter.

A pit will also be excavated in intersection 7 in January to allow the later installation of experiment R703T (evaluation of a large streamer chamber detection system and a study of pp-

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differences). The streamer chambers and associated camera system are being built in EF Division for experiment UA5 on the SPS collider, but the complete experiment will first be commissioned at the ISR. The design of the supporting structures for the chambers, cameras and hodoscopes is being carried out in the ISR Division and is well advanced. Prototype light-tight boxes for the hodoscopes have been constructed and tested and the moulds needed to produce the final 100 counters have been ordered. A vacuum chamber of the "flat-fish" type with a special internal support to obtain as low a profile as possible is under construction in the ISR workshop and is expected to be ready for installation in intersection 7 in January 1980.

Work has also started on the general layout of two recently approved experiments, R210 (a precise measurement of the total cross-section) and R211 (a measurement of the total cross-section

and small-angle scattering) which will be installed in intersection 2 during the three-month shutdown planned for the summer of next year. Experiment R211 will use the existing infra-structure of the so-called "Roman Pots" but new, more transparent, re-entrant vacuum chambers are needed to allow simultaneous operation of the two experiments. A design has already been produced and construction of a prototype chamber will start shortly. A new supporting structure for the existing intersection vacuum chamber is being designed and preliminary design work is in progress on modifications to existing hodoscopes and the construction of some new ones for experiment R210.

During the summer shutdown of next year, the superconducting high-luminosity insertion will be installed in intersection 8 for experiment R807, the construction of components having progressed satisfactorily during this year. Almost the whole supply of superconducting wire (1200 kg) has been delivered, tested and insulated. Four quadrupoles have been received from the manufacturer, equipped with auxiliary windings, assembled into their special cryostats and thoroughly tested. All these magnets have operated steadily at quadrupole gradients of 43 T.m-1, which correspond to maximum fields of 5.5 Τ in the windings, and with an additional sex-tupole component of 21 T.m-2. Their cryogenic performances are satisfactory and the magnetic field distributions meet the stringent tolerances of the insertion. Two other quadrupoles are in different stages of assembly and the coils for the seventh are ready. All parts of their cryostats are also ready.

The 850 kW compressor for the helium liquefaction plant has been installed. The extension of auxiliary building A8, which will house the 270 l.h-1 helium liquefier, the cryogenic controls and the power supplies for the magnets, is finished and installation of the liquefier will start shortly. The first of the eight liquid helium transfer lines has been received while all other cryogenic components, such as valves, flow-meters, feed throughs and pumps are either in hand or in production.

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The power supplies for the superconducting magnets have been delivered and are being tested. The data acquisition system for the control and monitoring of the magnets and of the helium liquefier is being installed including a "quench recorder" that will permit the detailed analysis of any resistive transition in the superconducting magnet windings.

In anticipation of the operational requirements of the ISR with the superconducting insertions special vacuum chamber units, incorporating beam position monitors and vacuum pumps, are being prepared. Computations of expected injection trajectories and of aperture limitations have shown the need to modify the layout of beam stoppers and collimators in both rings to prevent the beam losses in the insertion from exceeding the values which would induce resistive transitions in the superconducting magnets. The needs of these computations have also stimulated an improvement of existing beam optics programs.

3. DEVELOPMENT OF THE STORAGE RINGS

Machine studies this year were limited to those necessary to meet requests from the experimental teams for higher luminosity and improved beam conditions and to beam-beam tune-shift tests relevant to the SPS project. Similarly, equipment improvements were confined to increasing the machine's efficiency, reliability and ease of operation.

3.1 Machine studies

The increase in intensity achieved brings the stacks in the ISR close to the transverse stability limit and so a large fraction of the machine studies has been devoted to this problem. A slight distortion of the working line in the Q-diagram can lead to a beam loss and make a time-consuming refill of the machine necessary. Therefore the working line of each stack can now be routinely measured with the tracking Q-diagram meter, an instrument which has been improved in sensitivity.; its precision has reached δQ = ± 10-3. The Q-shift due to space charge is compensated by applying a correction with the poleface windings, which is calculated from the current and the beam position in the vacuum chamber. This procedure has been refined to cope with the high-intensity stacks.

The use of the information obtained from the beam response to external excitation (beam transfer function) has been developed further. If a part of the stack approaches the stability limit an increase in the amplitude of the transfer function at the corresponding frequencies is observed. Based on this information the working line can be changed locally to increase the frequency spread in the critical region and to establish a more stable situation. This has led to the use of an "S-shaped" working line, having a derivative of Q which varies across the stack and producing a large local frequency spread where needed. With such a line a stack of over 50 A was obtained. The analysis of the transfer function data has been extended so that the stability diagram of the

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stack can be displayed. This will allow the correction of the data for the effect of the wall impedance and the determination of the working line.

Since the transverse feedback systems are so essential for the stability of intense beams, their phase and gain have been carefully checked by observing the change in the transfer function of the beam due to the feedback systems. The investigation of overlap knock-out and other effects, which increase the vertical beam dimension, has also been continued.

Some experiments have been done in the ISR to help predict the beam-beam effect in future proton-antiproton colliders. To detect any vertical blow-up of a bunched beam colliding with a large stack, the luminosity was observed over a long time. The beam-beam tune shift per intersection was ∆Q = 0.001; no effect due to this could be observed. These measurements will be extended to larger tune shifts by adapting the low-beta insertion to give high-beta operation.

Continuing the experiment described last year to determine whether vacuum stability would permit the vacuum chamber of a superconducting proton storage ring to be cooled down along with the magnets, the 1.2 m "cold bore" test section was maintained in an unbaked condition at 4.2 Κ for 19 days of normal machine operation. Vacuum conditions were completely stable even at 38 A, demonstrating convincingly the potential of the "cold bore" concept for any superconducting machine design of the future.

3.2 Improvements

During the shutdown at the beginning of the year, the installation of the higher-harmonic RF system was completed. This system, consisting of one RF cavity per ring, tuned to the third harmonic of the main RF frequency, i.e. 28.5 MHz, and driven by a 20 kW RF amplifier, together with its low-level and controls electronics became operational in April. It is now used regularly during ISR operation, and permits injection of up to 250 mA per pulse, leading to stack densities in excess of 1 A/mm of radial aperture with stacked currents around 50 A. In order to stabilize these higher densities and currents against transverse instabilities, improvements have been made to the existing 1 MHz feedback system and development of the 50 MHz version is continuing.

The Fast Fourier Transform (FFT) analysing system installed last year is now connected to the ARGUS computer and permits automatic acquisition of the Beam Transfer Function. The FFT analyser is also used for measurements of longitudinal and transverse characteristics of stacks, hence replacing the older system based on the normal spectrum analyser and resulting in much faster acquisition of information from the Schottky noise.

Other RF improvements have been carried out with the aim of improving reliability, flexibility and ease of operation. They

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include combining the interlock and protection systems for all the high-power systems, improving the low—level RF system and its controls, a new device for precise frequency and beam position measurements during acceleration and stacking and a new interface between the computer and the beam position monitoring system.

On the vacuum front, the beam limitation due to pressure runaway has dramatically receded from last year's stability level of 36-37 A to 45 A in both rings this year. Correspondingly, the short-term current records have risen from 44.5 and 44.3 to 50.8 and 49.2 A in rings 1 and 2 respectively. This has been achieved by extending the ISR method of argon/oxygen glow-discharge surface treatment of UHV chambers. Approximately 75% (i.e. 1.5 km) of the ISR machine has now been treated in this way resulting in an average pressure for the whole machine of 4 × 10 - 1 2 torr (N2 equivalent). A computer-controlled monitoring system for electron clearing currents has been commissioned and permits, among other things and on an operational basis, an accurate and rapid location of unwanted beam losses anywhere around the machine. It also gives a similar indication of vacuum leaks and a continuous picture of the dynamic "beam-path × vacuum pressure" integral.

Beam currents in ISR now being two and a half times the machine's design value, it was necessary to install new beam absorber blocks at the beginning of the year. Besides their now proven ability to stop 50 A beams the induced radioactivity around them is less than with the previous design while the reduced heating of the internal vacuum chamber during beam dumping minimizes pressure increases. The increased beam intensities have also required that a special effort be made to avoid a corresponding increase in the radiation background at the experimental intersections. This has been achieved by careful optimization of injection and stacking procedures, and particularly by the use of the collimator system. With the installation of additional units at the beginning of the year, this system now consists of four double and two single collimating blocks in each ring which, based on orbit measurements of the circulating beams, are individually computer-controlled to permit precise positioning during setting-up and stacking. Newly installed multichannel background recorders provide a comparative signal from the scintillation counters in each intersection as a reference for manual collimator adjustment during stable beam periods.

One of the major tasks associated with the control computer in the past year has been the rationalization of the alarm and monitoring system. The introduction of colour displays for each ring has greatly improved the presentation of fault situations to the operations crew, allowing them to assess the situation more readily and take remedial action. Confidence that the equipment is indeed being monitored for alarm conditions is vital and has been improved by the introduction of surveillance of the monitoring programs themselves. In addition to these basic improvements the amount of non-vital information presented on the alarm screens is reduced whereas specialist information on the faulty systems can be called upon at the touch of a button.

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3.3 Antiprotons in the ISR

By the end of 1978 a comparative study had been made between direct injection of antiprotons into the ISR at 3.5 GeV/c from the Antiproton Accumulator Ring (AA) and injection after acceleration in the PS. This showed that the latter option was the more viable and desirable, since it relieved the ISR of the task of accelerating the antiproton beam from 3.5 GeV/c, for which the ISR are manifestly ill-suited, and instead it made it possible to exploit the ISR's excellent storage capabilities, so enabling far higher luminosities to be reached. These advantages were felt to outweigh the slightly higher cost and the need to construct a new transfer line, to be called TT6, for transmitting the antiprotons from the PS to the existing transfer line TT1 for injection into ring 2 of the ISR. These proposals were accepted and the ISR anti-proton project was authorized by the Executive Board in January 1979.

The project programme foresaw a period of two years for the construction of TT6 and modifications to the ISR so that antiproton operation would be possible by the end of January 1981. By adopting a lattice for TT6 similar to that of its sister transfer line TT70, which will transmit antiprotons to the SPS, the ISR Division was able to benefit from the very considerable amount of work already done by the SPS Division and to order the majority of the magnets, the tunnel and the power cables as additions to existing contracts. The PS Division kindly offered 19 quadrupoles from secondary beam lines, which also helped to conserve precious time and money.

The excavation of the TT6 tunnel was started in May and approximately 25 m of tunnel were completed by a laborious semi-manual method before the boring machine could be transferred from TT70. Progress then rapidly accelerated, but only to be slowed down again by a 10 m wide layer of gravel belonging to an access ramp built for the construction of the booster. A little over two weeks of work, again mainly by hand, were required to pass through this gravel into solid rock where the rate of progress is typically 16 m per week. The schedule for the tunnel excavation is governed by the end-of-year ISR shutdown which provides the only opportunity before August 1980 for building the junction between TT6 and TT1. At present the schedule is extremely tight and the utmost is being done to respect it. At the mid-point in the excavation, the TT6 tunnel passes beneath the TT2 beam line, which poses a potential radiation hazard. Since it is crucial to the progress of the project that work on TT6 can continue during the operation of TT2, special collimators have been installed in the TT2 beam line to localize possible beam losses and shielding has been added on the floor of the tunnel.

Work on other aspects of the transfer line is well advanced. The vacuum system, whose chambers will mostly be joined by welding, is almost completely designed and the majority of the components are ordered. It was possible to match almost all of the ISR spare power supplies to the TT6 elements leaving only a minority of power supplies to be ordered from industry. For its future operation, TT6 will depend heavily on beam position monitors capable of

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detecting very low-intensity, antiproton pulses and on Hall-plate field monitors for checking magnets and setting steering magnets. The hardware for both of these systems is currently being produced.

Some slim dipoles, whose apertures exceed their core lengths, have been specially designed for steering the proton and antiproton beams into head-on collision in the ISR superconducting solenoid in intersection 1. These magnets, and a smaller-gap version for steering in TT6, are currently being manufactured by industry. The necessary modifications to the SFM vacuum chamber in intersection 4 will not be executed until next year. The beam position monitors, RF beam control systems and injection-error damping magnets in ring 2 must be able to detect low-intensity antiproton pulses and development work has started on the required changes to the electronics. The necessary polarity inverter for the ring 2 inflector has already been installed and the opportunity taken to change to air- rather than oil-cooling of the thyratrons so reducing the risk of fire.

Preparatory work has started on the development and installation of stochastic cooling equipment for both protons and antiprotons, to be used when the antiprotons become available to the ISR. The existing experimental microwave cooling system previously installed in ring 2 has been removed. After modifications, it will be installed in ring 1 and used for cooling proton stacks at reduced intensity. A system of simpler design, operating at a lower frequency (150 to 650 MHz), is being installed in ring 2 for cooling the antiprotons.

4. THE ANTIPROTON ACCUMULATOR

The overall responsibility for the Antiproton Accumulator project rests with the PS Division and further details will be found in that section of this report. However, a large proportion of the ISR staff, together with technical services and space have been made available for this work and the main contributions and responsibilities of the ISR Division will be mentioned here.

The design of the entire ultra-high vacuum system has been completed and manufacture or purchase of the equipment arranged. This has required that outgassing tests be carried out on samples of the steel, ferrite and aluminium used in the construction of the various components and that much effort be devoted to acceptance testing of chambers, tanks, pumps, gate-valves, feedthroughs, etc. and to calibration of UHV gauges and residual gas analysers. A large amount of electronics has also been designed, particular examples being the power supplies of constant-rate sublimation pumps, computer-controlled UHV gauge power supplies and microprocessor-controlled turbomolecular pumping stations.

Design, construction and measurement of prototype stochastic cooling equipment has continued. Among the major items required are large-aperture ferrite-loaded sum pick-ups and momentum correctors to provide tight wide-band coupling, as required for fast—

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momentum cooling of low—density beams. Periodic comb filters using seven large—diameter precision transmission lines have been built while five partial-aperture pick-ups and three kickers for momentum and betatron cooling are under construction. To ease the running-in and routine check-outs an automatic network analyser, operated by a desk computer and situated in the AA control room, is planned; this will be able to measure inside the AA hall the detailed phase and amplitude characteristics of installed feedback systems, even in the presence of beam.

Specification and ordering of the power parts of the magnet power supplies have been completed, while the associated control electronics has been designed and construction organized. The construction of d.c. transformers to measure the intensity of the anti-proton beam is also under the responsibility of the ISR as are the testing, installation and commissioning of the equipment mentioned above.

5. THE LEP STUDY

The design of a large electron-positron storage ring - called LEP - is continuing. This study, while originating in, and remaining based at, CERN, is progressing with wide and intense participation by accelerator laboratories outside CERN and by the LEP Working Group set up by ECFA. In the course of the last year, this Working Group held meetings in Rome, Hamburg, Geneva and again Rome. A milestone was reached last August when a new detailed design report was issued. It contains a description of a new machine, LEP Version 8, and of the progress made in the design of systems and components made since the previous design report, issued in 1978.

The present phase of the LEP studies was started during the autumn of 1978. Following the recommendations of the LEP Summer Study at Les Houches in September 1978, and strong encouragement by ECFA and the Scientific Policy Committee, the accelerator's circumference has been increased to just over 30 km. The energy at which the maximum luminosity of about 10 3 2 cm - 2s - 1 occurs with RF cavities made of copper was increased to about 86 GeV, while the maximum energy attainable with superconducting RF cavities was raised to 130 GeV. Detailed parameters and performance estimates have been worked out for this machine.

Engineering studies for several systems and components are being pursued and novel techniques developed for building the magnets, the RF system and the vacuum chamber. Twenty test borings to find the exact level of the top of the molasse across the proposed site have already been finished and another twenty will be made by the end of the year.

5.1 Performance

The machine has a circumference of 30.6 km. In its nominal form, called Stage 1, an energy of 86 GeV and a luminosity of

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10 3 2 cm+2s+1 will be obtained by means of an RF system using copper cavities, the only solution that can be safely proposed at present, and an RF power of 96 MW. Between 22 and 86 GeV, the luminosity is proportional to E2, this variation being obtained by a system of wiggler magnets. With an RF system using copper cavities, the performance at high energies is limited by the RF power dissipation in the cavities. There is good reason to believe, however, that superconducting cavities will become operational with adequate performance and at reasonable cost during the accelerator's lifetime. Therefore, a Stage 2, using superconducting cavities, is foreseen for energies much above 86 GeV. The circulating current is assumed to be limited by collective phenomena at injection and is hence kept constant up to an energy where most of the available RF power is converted into synchrotron radiation. Above that energy, about 117 GeV, the synchrotron radiation power is kept constant. The maximum energy at full luminosity, 130 GeV, is determined by the installed RF power, the accelerating field gradient in the cavities reaching 5 MV/m at this energy. The magnet and vacuum systems will be constructed so as to permit this extension to 130 GeV with only minor modifications, as soon as a suitable RF system becomes available.

Since it may be desirable to start colliding-beam physics at the earliest possible moment, albeit at reduced energy, a staged construction of LEP can be envisaged. A detailed investigation has shown that the most economical and practical solutions consists in installing only a fraction of the RF system but the complete magnet and vacuum systems. Colliding beams of worthwhile energy could be obtained when only 1/6 of the nominal complement of room-temperature cavities and power sources is installed but we have singled out the stage of construction in which one third of the full complement of cavities and power sources is installed. In this Stage 1/3, an energy of 62 GeV with a luminosity of 0.6×1032 cm-2s-1 can be obtained, making LEP a very worthwhile ZO factory. The option is left open of continuing by either installing the full complement of room-temperature cavities to reach Stage 1 or, possibly, going to superconducting cavities at once.

If, against all expectations, superconducting cavities should not become available, it would be possible to install an additional 1/3 of the nominal complement of copper cavities in the reserve space foreseen in the lattice, while increasing the RF power to 128 MW. In this Stage 4/3, the maximum energy would be about 93 GeV at full luminosity and about 100 GeV at 10% luminosity. A summary of the most important parameters of these stages is given in Table 2.

Eight experimental areas are foreseen. Four of them are designed for the nominal luminosity of about 1032 cm-2s-1 with a free space between the nearest quadrupoles of ± 5 m. The remaining four regions have a free space of ± 10 m and half the luminosity. Three experimental areas are situated in the flank of the Jura and will be accessible via individual, almost horizontal access tunnels.

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Two areas come close to, and can be excavated from, the surface. The remaining areas will be accessible via pits. Compared to the previous design, the total volume of the experimental areas has been doubled, following another recommendation of the LEP Summer Study.

Table 2 - LEP Energy Stages

Stage 1/6 1/3 1 4/3 2

Design energy GeV 49.4 62.3 86.1 92.9 130 Luminosity 1032cm-2s-1 0.385 0.616 1.07 1.15 1.04 Current mA 5.71 7.20 9.15 9.15 6.16 RF power MW 16 32 96 128 96 Length of RF m 272 543 1628 2172 1629

5.2 Engineering

In the design of the LEP dipole magnets, advantage is taken of the unusually low field (0.123 Τ at 130 GeV) to reduce the filling factor in the core to 0.27. These cores will be made of precisely punched steel laminations interspaced with concrete, the field distribution in the gap being determined by the steel profile. To this end, spacers are pressed into the laminations of 1.5 mm thickness by the punching die, so that the laminations are spaced with a 5.5 mm pitch. The assembly is placed in a mould and the space between the laminations filled with a low-shrinkage corrosion-inhibiting mortar composed of cement and fine grain silica sand. Longitudinal tie rods, passing through punched holes near the outer edges of the laminations, precompress the mortar. As the price and density of concrete are much less than those of steel, both the cost and weight of the dipoles will be reduced by about a factor of two. The much improved mechanical properties are a further advantage of the steel-concrete cores. Three models of half cross-sectional scale and 60 cm length have been built and tested, both mechanically and magnetically. The field uniformity in the gap is the same as for a conventional core. The small increase in the remanent field (6 G instead of 5 G) and of the excitation current at the highest energy (5% at 130 GeV) do not affect the machine performance and have a negligible effect on the overall cost of the magnet system including power supplies. In August, a full-size magnet, 5.68 m long, was built and mechanical tests have shown that the rigidity in torsion and flexion is improved by factors of 20 and 6, respectively, compared to a typical laminated magnet and that the strain-stress hysteresis is reduced, i.e. the residual twist after a torsion is smaller by a factor of 9.

The low field required also permits excitation by simple aluminium-bar conductors instead of the usual multiturn coils. The bars are insulated by overlapping half shells made of glass-fibre reinforced polyester and are not only far cheaper than traditional coils but minimize the space lost at the junction between cores.

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This system of excitation has been installed on the full-size model. A special power supply (12 V, 5200 A) has been delivered by industry, and magnetic tests have been started.

Since the lattice quadrupoles and sextupoles have to reach the highest possible field levels in the poles, they are designed as conventional laminated magnets. However, their excitation coils will be wound with solid anodized-aluminium strips, instead of hollow conductors. The advantages are a simplification of the coil design giving a reduction of the cost and an increase of the aluminium filling factor which results in more compact magnets and smaller power dissipation. Tenders for prototype coils are in preparation.

The basic vacuum system design for LEP involves a water-cooled chamber made of extruded aluminium and distributed sputterion pumps immersed in the dipole field, similar to those of SPEAR, PETRA and PEP. New problems arise because of the critical energy of the synchrotron radiation (400 keV, an order of magnitude higher than in PETRA or PEP) and because of the lower dipole field. A considerable thickness of lead shielding is required to prevent an excessive amount of radiation in the tunnel, where corrosive and toxic chemicals would be generated from air and humidity. The lead shield required for Stage 1, 8 mm at the sides of the chamber and 3 mm opposite the magnet poles, will be bonded to the aluminium chamber by a continuous process of extrusion or hot rolling. Samples prepared by these methods have been obtained from industry and short sections of aluminium chambers with the lead coating are on order. The distributed outgassing load due to radiative and thermal desorption will be absorbed by a linear, distributed sputter-ion pump situated in the field of the dipole magnets. The pole width, determined by the required field uniformity, accommodates pump cells of 50 mm diameter. The discharge in these cells can be maintained down to about 180 G, well below the injection field in LEP. In order to arrive at an acceptable cost for the 22 km of pumps their anodes will be made of superimposed layers of thin stainless steel strips, manufactured in a continuous process. A 3 m long prototype section of such a pump structure has been tested in the laboratory and preliminary results show that a static pressure of well below 10-9 torr can be obtained over the full magnetic field range. Depending on the pressure, a maximum value between 30 and 60 1 s-1m-1 has been measured for the effective linear pumping speed at the design field for 86 GeV.

The RF system is based on room temperature cavities, with an accelerating structure made up of five-cell slot-coupled cavities. It is proposed to add so-called storage cavities to this system, to increase the effective shunt impedance by a factor of 1.5. The method used is to couple a low-loss, Η-mode, storage resonator to the accelerating cavity and to excite the coupled septum from CW power sources with both its resonant frequencies. This makes the stored energy oscillate between the two resonators so spending, on an average, half the time in the low-loss environment.

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Computation has shown that one common storage resonator is sufficient for each five-cell accelerating cavity and this has been confirmed by measurements with a 500 MHz model consisting of an experimental storage cavity coupled to a PETRA cavity kindly lent to CERN by DESY. The storage resonators will be spherical and formed from sheet copper. So far a half-scale model has been built and Q-factors of up to 95% of the theoretical value have been measured. A ball tuner has also been tested and several couplers, including ridged waveguides have been tried. A 500 MHz storage resonator suitable for high power tests is under construction, while a corresponding accelerating cavity and a high-power klystron are on hand so that tests under power should be possible early next year. Work has also started on the necessary controls circuits for the cavities and the klystrons. Feasibility studies are also being made of a switched coupler between the accelerating cavity and the storage resonator. Such a switch would permit the stored energy to be kept in the low-loss environment for a larger fraction of time and hence further increase the effective shunt impedance.

A feasibility study of superconducting cavities for LEP was started at the beginning of the year and will require basic research to be carried out in four main directions. Surface treatment studies in conjunction with the use of re-entrant, 500 MHz cavities will determine the surface conditions necessary to achieve the niobium BCS Q-value at 4.2 Κ with acceptable secondary emission coefficients, and shed light on field-induced electron emission mechanisms. Work on spherical and sharp-corner cylindrical single-cell superconducting cavities at 0.5, 3.0 and 4.5 GHz should determine how accelerating fields achieved at higher frequencies scale with decreasing frequency and the effect of cavity geometry on multipactoring. Particularly important will be a study of accelerating multi-cell structures again at 0.5, 3.0 and 4.5 GHz. The aim is to compare multipactoring phenomena in single- and multi-cell structures, to determine the required construction tolerances of the complex structures, how to design and construct the frequency tuners and the power couplers for the fundamental frequency and how to couple out the power dissipated in the cavity by the excitation of higher-order modes. Only when these structures are understood, especially the 0.5 GHz versions operating in the presence of an electron beam, will it be possible to decide when Stage 2 of LEP construction can start. Finally, since required refrigeration power is a function of the Q-values of the accelerating structures, some effort will be devoted to searching for high Q-values and understanding Q-limiting mechanisms.

The superconducting RF cavity research is being carried out mainly in the EF and ISR Divisions in conjunction with the universities of Genoa, Paris XI-Orsay and Wuppertal. Some of the results obtained so far are described in the EF Division section of this Report. In the ISR Division, an extensive series of secondary electron yield measurements as a function of the incident electron energy, angle, integrated dose and as a function of the niobium surface temperature and pre-treatment has been completed and

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will permit improved calculations of cavity multipactoring phenomena. It has also been shown that a vacuum bakeout reduces the secondary electron yield for niobium by some 30% and increases by a factor of two the threshold energy, for a yield of 1. In-depth chemical analysis by Auger spectroscopy of the first few 100 Å of surface has given interesting information on the surface contamination and the structure of the oxide overlayer. Scanning electron microscope studies are beginning to reveal a variety of unsuspected effects, such as impurity segregation, especially near welds, on the surfaces of previously cleaned niobium sheet metal. The development of a bakeable superconducting vacuum seal, the use of (in situ) glow-discharge cleaning by inert ion bombardment and the modification of surface properties by ion implantation are being pursued.

6. COLLABORATION WITH OTHER DIVISIONS AND EXTERNAL LABORATORIES

CERN (ISR) and DESY have continued their financial participation in the joint development programme with KfK, Karlsruhe to produce a superconducting RF cavity for installation in the DORIS storage ring. This will provide practical operating experience in electron machines and permit studies of higher-order mode excitation and the influence of electron bombardment and synchrotron radiation on the performance of the cavities.

Many ISR staff were included in the specialist groups of the ECFA Working Group looking at the overall and detail aspects of the LEP project. Others spent extended periods at PETRA as part of the CERN/DESY collaboration to develop PETRA and to extend machine studies to LEP problems. Contributions were also made to the collaboration with China for the design of a 50 GeV PS, to ICFA and to laboratories in the USA whilst papers were prepared for many conferences.

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SPS DIVISION

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SPS DIVISION

1. INTRODUCTION

The most important events for the future of the SPS, which occurred in 1979, were the advancement of the work for all aspects of the proton-antiproton colliding beam project and the completion of the third North Experimental Area, the high-intensity facility called NAHIF.

The operation of the accelerator was interrupted a few times by failures of important equipment resulting in a total loss of 15 days. Some of these failures occurred in period 5 (October), when the maximum energy was raised from 400 to 450 GeV. As a consequence, the operation at energies above 400 GeV had to be discontinued, but the normal operation could be resumed in good conditions for the last week of period 5. For the rest of the time the accelerator ran very satisfactorily and despite the lost time and the longer cycle, the total number of protons delivered to targets was larger than in 1978.

2. THE SPS ACCELERATOR

2.1 Operation of the SPS

The cycle used for SPS operation in 1979 was very similar to the one of the previous year, the main difference being that the energy of the intermediate flat top was raised from 210 GeV to 240 GeV and later to 250 GeV in order to increase the intensity of the secondary beams in the West Hall. On each cycle five different extractions sent scheduled fractions of the circulating beam to the West and North Areas. In order to reduce the time lost for machine stops and setting up, the length of the operation periods was increased from five to seven weeks, each period having three ten-day physics runs, separated by machine development sessions.

The number of operating hours scheduled for 1979 were as follows:

Setting up 183 Machine development 913 Physics 4449 Total 5545

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Double-batch injection with a cycle time of 9.6 s has now become a routine operation and with a well-adjusted machine about 2 × 1013 ppp are accelerated beyond 200 GeV. During period 3 the SPS operated with three-batch injection and a cycle time of 10.8 s. However, the intensity could be increased only to 2.2 × 1013 ppp and was limited by longitudinal instabilities at injection. The dipole instabilities could be damped up to mode numbers around 20 with a new feedback system, but the quadrupole modes which are nearly as dangerous at injection, can only be damped with the 800 MHz Landau damping system, of which the first cavity will be installed in January 1980.

During the first half of period 5 the SPS operated with a 1.2 s flat top at 450 GeV, while the tune was decreased from Q = 26.6 to Q = 25.6 because of saturation in the main ring quadrupoles. However, an inspection which was carried out during this period showed excessive heating of the connections and stresses in the coils in a number of transformers of the power supplies of the main ring dipoles and quadrupoles. For this reason and also because of the extraction difficulties mentioned below, the flat-top energy of the SPS during the remainder of the year was kept at its design value of 400 GeV.

As already mentioned, during the year 1979 the SPS operation was interrupted a few times by substantial failures of equipment.

In April, an 18 kV circuit breaker developed a short-circuit to ground and caused a fire in the electrical distribution building. Fortunately the damage was limited to only three circuit breakers and, after one week of intensive repair work, SPS operation could be resumed.

In September, a flashover occurred between the busbars of the main ring dipoles, probably due to condensation on an insulating support of the busbars. As a result, flashovers occurred also across several adjacent supports and the repairs took about three days.

In October, while the SPS was operating at 450 GeV, and with coherent fast resonant extraction in two turns for the neutrino experiment, the 4.2 mm water-cooled copper septum of the first thin septum magnet in LSS6 was pierced on two occasions by the extracted beam, which had an intensity of about 1.2 × 1013 ppp. In both cases cooling water was spilled into the vacuum tanks. This necessitated not only the exchange of the damaged septum magnet, but also of instrumentation modules and, in the second case, even of the electrostatic septum tanks. To reduce the probability of further accidents, a 5 mm thick aluminium dummy septum was installed just upstream of the thin septum magnets and stricter operating procedures were introduced for both extraction systems.

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Nevertheless, because of the increased circulating beam intensity, the total number of protons delivered to the targets was larger than in 1978 and is given in Table I.

Table I

Protons delivered to the targets

Period Protons 5 1018

1 2.99 2 2.72 3 2.95 4 3.29 5 1.77 6 ~ 3

Total ~16.8

Outside the major breakdowns, the time available for physics was about 85% of the scheduled time.

In a limited number of bending magnets assembled at the beginning of the SPS construction, minor movements of the coils occur during pulsing and are transmitted to the vacuum chamber. This leads to a fatigue phenomenon which caused leaks in a few chambers. Usually these leaks develop slowly so that the magnet concerned can be exchanged during a scheduled machine stop.

The evolution of the closed orbit at high energy was followed closely and was corrected by finding the best set of main quadrupoles to be displaced transversely. The main disturbance occurred in the spring, during the large excavation in LSS5 for the experimental facility. This necessitated in June a complete levelling of LSS5 with maximum displacements of up to 3.3 mm in the worst case (QD 319).

2.2 Machine physics studies

About one third of the machine physics studies was devoted to short-term developments for the current SPS operation, such as optimization of new operational cycles, triple-batch injection, studies of working points around Q = 21.4 and Q = 25.6 for operation above 400 GeV, improvements to the slow extraction spill, etc.

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About two thirds of the machine physics studies were devoted to subjects related to the project.

For the study of intense single bunches, the machine tune was lowered to Q = 15.4, corresponding to a transition momentum of 13.4 GeV/c. This allows protons to be injected above transition at 15.8 GeV/c, the maximum of the injection beam line, and single bunches of 1011 protons to be accelerated to the coasting momentum, which was usually 210 GeV/c in these experiments.

At the beginning of the storage, when the longitudinal emittance is small, the bunch length oscillates coherently, mainly in the quadrupole mode. During this "turbulent" period, which can last up to 30 minutes, the longitudinal emittance gradually increases until the bunch stabilizes owing to bucket non-linearities, with a length of about 3 to 3.5 ns.

Once the coherent phase has died away, protons diffuse out of the bucket owing to RF noise. Experimental observations and a theoretical analysis, which takes into account the effect of the radial and phase feedback loops of the RF system, show that the rate of longitudinal emittance blow-up due to noise is proportional to the square of the synchrotron frequency spread, the latter being in turn proportional to the square of the bunch length. Therefore, the long bunches produced by the turbulent phase are particularly sensitive to noise.

To improve this situation, a feedback system has been constructed to damp the quadrupole mode of the bunch oscillations. This resulted in an equilibrium bunch length of 2- 2.3 ns. Further experiments have concentrated on reducing the diffusion rate. Since the band-width of the radial loop of the RF system was found to have a significant effect on the lifetime of the stored bunch, the radial loop was eliminated by locking the RF to an external frequency which then determines the radial position. The effective band-width of this synchronization loop can in turn be reduced to very low values. In this way, a lifetime of about ten hours after two hours of coasting could be obtained.

Since the bucket area is proportional to the Q-value, further experiments of the diffusion from single bunches have been made at Q = 26.6. The protons were injected at 10 GeV/c and single bunches of a few times 1010 protons were accelerated through transition. During coasts at 210 GeV/c the lifetime due to diffusion out of the RF bucket was about 24 hours, after two hours of coasting.

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In parallel with this work, the transverse emittance blow-up has been studied, usually with continuous beams, with and without RF on. All storage experiments, one of them lasting nine hours, showed lifetimes of about 50 hours, in good agreement with the calculated nuclear scattering lifetime, irrespective of Q chromaticity, and whether the RF was on or off. However, the transverse emittance growth, measured with scrapers, was two to four times faster than what can be calculated from the N2-equivalent multiple scattering pressure of 3.2 × 10-9 Torr, deduced from gauge readings and the measured composition of the residual gas.

Since this effect could be caused by higher-order resonances, further studies to determine the effect of the exact working point and chromaticity on the emittance blow-up are in progress and a new, very sensitive detector for transverse Schottky scans is being tested to improve the diagnostics.

2.3 The intensity improvement programme

Practically all components for the new multibatch inflector have been delivered, with the exception of the vacuum tanks which are somewhat delayed because of late delivery of the stainless steel. The first completely assembled pulse generator is ready for high-voltage tests. The first kicker magnet module has been tested successfully at low voltage and the assembly line for the series of 12 modules has been started. The high-power coaxial cables between the equipment building and LSS1 have already been installed. The dump block downstream of the inflector, which absorbs the injected protons when the inflector is not pulsed, has been entirely redesigned for the higher intensity and its components are on order.

The fourth 200 MHz accelerating cavity was installed in January and the SPS is now operated with a total RF power of up to 2 MW. All four cavities are strongly damped at the 460 MHz deflecting mode and have also been improved concerning their reflections at 200 MHz.

Commissioning of the second transmitter plant, which will provide an additional 2 MW of RF power is well under way and its first two 500 kW transmitters have already operated at full power. All feeder line components, power splitters and additional loads to operate each cavity with an RF power up to 1 MW, were ordered.

The two 255 kW amplifiers of the 800 MHz Landau damping system have successfully passed the acceptance tests and are now used to test high-power components of the 800 MHz system. The manufacturing of the first of the two 800 MHz cavities is proceeding well and its wave-guide will be installed in the second half of 1980.

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The manufacture and installation of the second half of the eight cavities and amplifiers for prebunching the circulating CPS beam at 200 MHz was completed in the spring of 1979. This system is now in continuous service and the responsibility for its operation and further improvement has been transferred to the Proton Synchrotron Division.

2.4 Machine completion and development

The stronger water-cooled sextupoles and the new octupoles were installed and their power supplies were commissioned.

The new damper, which was designed for damping the resistive wall instabilities up to 5 × 1013 ppp for fixed target operation and for reducing the injection oscillations in the mode, was installed and is being commissioned. It will have a new data module subroutine which allows all its settings to be controlled from the MCR.

The B-train for the regulation of the main ring power supplies was rebuilt completely. The magnet currents at injection are now stabilized by means of direct current transformers rather than via signals derived from peaking strips. This has considerably improved the stability of the injection field and also permits extended flat bottoms for injection and long coasts at high energy.

The third switch in the TT60 switchyard, which deflects the beam towards target T11 for the narrow-band neutrino beam, was redesigned since the aperture of the present switch magnets is too small for the coherent fast resonant extracted beam, which has an emittance several times larger than the one of the circulating beam. The new switch will be installed in the long 1980 shutdown.

All additional or modified components for the upgraded internal beam-dumping system are on order. The main absorber block was entirely redesigned. Its aperture was enlarged to permit passage of the injection beam since the beam-dumping system will be removed from LSS4, to make room for experiments, and will be installed in LSS1, interwoven with the injection system. Special attention was paid to a construction which should allow the absorption of proton intensities up to 4 × 1013 ppp at 450 GeV/c, which represent a stored energy of 2.9 MJ.

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2.5 The computer control system

The accelerator down-time for this system was usually kept at around 1%, by intensive maintenance and the use of a comprehensive system of diagnostic programs. Its weakest components are the computer drums and data links and, therefore, a considerable effort was devoted throughout the year on projects to eliminate the drums and to provide for remotely switched replacement of data-link repeaters. The former project is in an advanced state. Three computers were already converted and now have only solid-state memory, resulting in an increased reliability and greatly improved response. This change required the reorganization of a large amount of software, especially in view of the need for the change-over to be invisible to the users of the control system. The project for doubling the data-link repeaters was completed and central controls now exist enabling an SPS operator to replace a faulty repeater by remote control, an important feature when road distances up to 4 km are involved.

The CIMBUS, and SPS standard for microprocessor-based projects was fully defined and prototypes of its different plug-in units were constructed. It is possible to interface it with the SPS general-purpose multiplex system with the minimum of software support, but it can also be used independently. CIMBUS is currently being used to design the instrumentation project to control the 2000 additional high-vacuum pumps, which will be installed for improving the SPS vacuum for the project.

An autonomous CAMAC crate controler, a CAMAC unit incorporating a 16-bit microprocessor, was designed and a number of these ACCs have been ordered from industry. They will be used for distributing some of the processing beyond the control computers. The pilot project using this equipment is the new beam-position instrumentation for the project, where the microcomputer will contain a data-module subroutine written in NODAL.

Post-mortem equipment, in the form of two multiplex units, was designed and built. It will enable machine physicists to obtain playbacks of key machine variables in the period just before beam loss during storage runs.

An extensive program of data module documentations was carried out and laid down in four manuals, which contain virtually all the information needed to write control programs in NODAL.

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An additional "NEWS" computer was installed to take over the generation of fixed displays and target statistics from the DISPLAY computer. This has greatly improved the response of the display computer and allows additional continuously updated displays on the MCR consoles.

The analogue signal selection software was completely rewritten and this has made this system much more reliable and usable. An intelligent touch terminal, using microprocessors and CAMAC was developed to permit analogue signal selection without requiring a console. Several new CAMAC modules were developed in preparation for a major update of the MCR console facilities, such as character generators, cursors and high-resolution displays during the long shutdown.

2.6 The proton-antiproton colliding beam project

The excavation of the TT70 tunnel, through which the 26 GeV antiprotons will travel from the PS to the SPS, was finished and its civil engineering is being completed on schedule. The prototype qua-drupole was delivered and a prototype dipole is almost ready for delivery. The steering dipoles, the slim quadrupole at the exit from the PS, vacuum chambers and other vacuum components, magnet supports, power supplies, cables, etc. for TT70 are all on order.

Antiprotons will be injected into the SPS through TT60 and the extraction system in LSS6. The power supplies of TT60 are being adapted for operation at 26 GeV. The original plan was to inject 12 antiproton bunches which would be accelerated to 270 GeV and then combined two by two into six bunches. The machine physics studies described above showed that the large bunch area resulting from recombination in longitudinal phase space would lead to rapid particle loss due to diffusion. Therefore, this idea was abandoned and it is now planned to achieve two-by-two combination of the antiproton bunches at injection in horizontal transverse phase space by two-turn injection. This system makes use of the electrostatic septum normally used for extraction and requires the installation of two additional injection kickers to make a rapid local closed orbit deformation.

The modules for the fast antiproton inflector are identical to those of the new multibatch inflector and all components are on order.

The protons will be injected in the form of six bunches at 26 GeV. Additional septum magnets and other bending magnets and a number of power supplies to upgrade the injection beam line and the injection system to 26 GeV were ordered.

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Extensive design work was undertaken in order to fit the injection system, the upgraded beam-dumping system and the Q-measuring kickers, which have to be removed from LSS4 and LSS5 into LSS1 and an acceptable layout was found.

The civil engineering work for a 400 m2 extension of equipment building BA1, necessary to house the additional pulse generators, was completed on schedule.

To impove the SPS vacuum to 10-9 Torr, about 500 additional sputter ion pumps and about 1500 sublimation pumps will be installed. These pumps and their power supplies are now being delivered and tested and most of the cables were already laid down. Compact, microprocessor-based control equipment in each equipment building will offer great flexibility in operating procedures and will allow full control from the MCR.

The high-power switches to reverse the direction of power flow in two of the four 200 MHz cavities and one of the two 800 MHz cavities, and the associated components for the acceleration of anti-protons were ordered.

The design of the low-level RF system for the project was started, on the basis of the machine physics studies with single bunches. To improve the synchronization between the PS and SPS to the accuracy required for the transfer of single bunches, a glass fibre cable with a band-width of 300 MHz was ordered and will be installed between the two machines.

Extensive tests are being made to obtain the required stability of the main ring power supplies for operation. The need for this work stems from the fact that the power supplies are controlled by voltage regulation via a learning program based on repetitive pulsing. During tests, the pulsing can be very irregular and this varying thermal history can upset the precision of the power supplies.

The power supplies for the low-beta quadrupoles and the high-current commutators, which connect these quadrupoles to either their individual power supplies for operation or to the normal magnet circuit for fixed-target operation, were all ordered. A prototype setup to produce the current reference program for the low-beta supplies, controlled by the low-beta computer, is being tested.

A total of 32 directional coupler beam-position monitors will be installed in the SPS to measure separately the position of the p and bunches. A prototype already installed in the SPS, has a directivity of 35 dB.

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The development of the non-destructive measurement of the transverse beam profile by means of synchrotron light was pursued actively. The light is focused on a silicon intensified target vidicon and analysed by a TV scan. Beam profiles with a resolution of 0.1 mm were obtained above 240 GeV/c with a beam intensity of 8 × 1012 ppp.

A new type of function generator was developed for operation. With the help of microprocessors, the generators will no longer be dependent on the SPS cycle for communication with the SPS control system. Microprocessors will automatically survey the function generator and power supply output currents. For the high-precision requirements of the operation, the drift and low-frequency output noise were considerably reduced.

Extensive studies were carried out for the chromaticity correction in the SPS with the low-beta insertions on. It was found that a satisfactory chromaticity correction down to βH × βV = 0.5 m × 1 m can be obtained by adding to the two existing families of 36 F- and 36 D-sextupoles two more families of 18 F- and 18 D-sextupoles, and by suitably choosing the ratio of the currents in these four families. The additional 36 sextupoles and the power supplies and cables were ordered.

The steering dipoles for closed-orbit correction on the low-beta section and their power supplies are also on order.

Four electrostatic deflectors, each 3 m long, will be installed in LSS5 to provide horizontal and vertical separation of the proton and antiproton beams in LSS4 and LSS5 for luminosity measurements. All major components for these deflectors, such as vacuum tanks and titanium electrodes, are on order.

A tungsten target with a diameter of 3 mm and a length of 110 mm, capable of sustaining temperature of up to 30000 C, was developed for use as production target of the antiprotons for the Antiproton Accumulator. The tungsten rod is embedded in a graphite sleeve which keeps the tungsten in place even when the target rod is fractured owing to elevated temperatures. A prototype was successfully tested for ten hours with the full PS beam.

The two major civil engineering contracts for the experimental areas in LSS5 and LSS4 were adjudicated in February and April respectively and the excavation work started promptly in both areas.

For LSS5, the excavation work of the first phase (leaving sufficient earth shielding around the existing SPS tunnel) was finished early in September. The concreting of the heavy floor structure at the bottom of these pits was finished by the end of October and the construction of the peripheral walls is in progress, roughly in line with the construction schedule.

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In LSS4, the two pits connecting the surface building to the underground area, one of 8 m diameter for the equipment and the other one of 5 m diameter for the personnel and the services, were completely excavated, together with the top part of the horizontal bottom tunnel which has a diameter of 20 m over its entire length of about 45 m.

All important contracts for equipping both areas with cranes, ventilation systems and other services were placed, and it is hoped that the first installation work may start in March 1980 in LSS5 and a few months later in LSS4.

A considerable effort was devoted to the design of equipment for the two large experiments UA1 and UA2, namely a rolling platform for the central part of UA1, weighing about 2000 t, a platform transported on air cushions for UA2 (350 t) and a rolling complex of 60 electronic racks, arranged on three levels, for UA1.

Movable devices are also under study for supporting the cables of the big experiments UA1 and UA2 when they are moved in and out of the SPS tunnel. All this was preceded by a careful study of the kinematics needed in order to assemble the detectors in a complete form in the garages and to exploit them in the beam. Very thin vacuum chambers have been studied in collaboration with the ISR Division and will be produced in sectors terminated by big valves so that no further baking is needed when the central detectors are brought into the SPS tunnel.

The manufacture of two compensating calorimeters (CALCOM) for UA1 is in progress. The first one should be ready by the early spring of 1980. Orders for the 24 coils of the two toroidal field magnets and for the large-angle spectrometer of UA2 were also placed.

Finally, complete layouts were drawn up in order to assess the compatibility of experimental equipment and machine components in the two areas LSS4 and LSS5.

3. EXPERIMENTAL AREAS

3.1 Operation of the areas and support to experiments

Eleven secondary beams serving twenty-three experiments were operated during the year.

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In the West Area, beams were modified to exploit primary proton momenta up to 250 GeV/c. This, together with shielding improvements to the H3 beam, was particularly beneficial to experiment WA11 in its search for "beauty". Tests facilities were provided, especially for the preparation of experiments. A scheme is in preparation to allow the test beam H5 to run at different momenta whilst recuperating the protons to produce the hyperon beam Y1.

In the North Area, one new beam (H6) and seven new experiments, requiring two additional spectrometers and four CEDAR counters, were brought into operation. A rotatable silicon crystal to convert gammas into electrons was tested and an increase of the electron yield of 22% was observed in the E4 beam. Eight hodoscope planes in the muon beam M2 were finalized and the controls software for the surveillance and diagnostics of all equipment was implemented in a more suitable version. Further measurements on particle production from 400 GeV/c protons on beryllium were made and a detailed report was issued. The electronics for the power supplies were modified to allow for pulsed operation of most of the beam line magnets resulting in a 50% power saving.

Considerable preparatory work was carried out in view of the installation of new experiments in EHN1 (EHS, NA13, NA16), in EHN2 (NA9) and in ECN3 (NA10, NA14) for the detailed layouts, the counting rooms and the realization of the dump for NA10, made out of tungsten, graphite and iron.

Important modifications and additions were made to other experiments, like the lead-glass detector of NA2 and the shielding of NA3 to allow the utilization of an attenuated proton beam.

It is worthwhile mentioning that the two superconducting dipoles, called MBS, and the quadrupole CASTOR which constitute a section of the H6 beam, have worked very satisfactorily since March 1979.

The SPS Division has operated all hydrogen targets at CERN, for 14 running experiments. Twelve of these targets were built or modified in 1979. A special delicate operation was the alternate filling with liquid H2 and D2 of a 120 l target for NA2. D2 was recuperated in liquid phase and kept liquid for the whole year. The new refrigerator BOC is undergoing systematic tests in preparation for the installation of the 50 m target of NA4 next year.

3.2 The high-intensity experimental zone

Preparation of the new North Area High-Intensity Facility (NAHIF) started after the completion of the civil engineering of the target zone TCC8 and of the experimental hall ECN3. The installation of the general services and of all beam elements along the Po, H10 and E12 lines was completed, their power supplies were tested and the

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monitoring system is ready to observe the first beam. In ECN3, one experiment (NA10) is being assembled, while the installation of NA14 has been somewhat delayed because of the prolonged data-taking of WA11 in the West Hall.

This new area, which will be penetrated by a high-intensity proton beam, required the installation of two new major access points controlled from the MCR, which add to the ten existing so far, and of more than 20 interlocked gates inside the area.

3.3 Technical delevopments

The construction of a fast pulsed magnet system for the proton beam branch to target T2 in the North Area is almost completed. It will deflect the beam rapidly away from the target during the time intervals of partial sensitivity of the rapid cycling bubble chamber.

The last three dipole magnets with radiation-resistant coils insulated with cement-impregnated asbestos tape were completed, while the first quadrupole is being assembled in industry with four coils made with the same insulation. The manufacture of coils for twelve complete quadrupoles was entrusted to industry.

For the 5 m long superconducting dipole, eventually to be part of a complete bending section in the new Po beam, various tools were completed and the superconducting cable ordered. Considerable effort was devoted to the design of the cryostat with its terminal boxes, the protection system and the forced helium cooling.

An upgraded version of the quadrupole CASTOR with Nb3-Sn superconducting cable is being prepared.

4. SERVICES

4.1 Civil engineering

In addition to the completion of the civil engineering and services for the high-intensity area already reported, the service building was finished this summer and is now completely occupied. This has enabled this Division to put large floor areas in the large assembly hall at the disposal of experimental teams.

In the course of this year, a storage area for radioactive equipment has been constructed on the Prévessin site, comprising a hall of 800 m2 equipped with a 30 t crane. This facility is now available to all users of the SPS machine and experimental areas.

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An area to store liquid hydrogen and test hydrogen targets on the Prévessin site was designed.

4.2 Electricity supply and cooling

As already mentioned, in April, a 18 kV circuit-breaker in the main feeder line to the magnet power supplies developed a short-circuit to ground and caused a fire, promptly mastered by the fire brigade. While provisional repair work permitted the resumption of operation after one week, the final repair, which made available again all magnet power supplies stations, could only be carried out in September.

This incident brought to light the need for better protection and for improved flexibility in the utilization of the three main transformers. Work along those lines was started and will culminate in a major overhaul during the long 1980 shutdown.

Extensive installations were completed in NAHIF, and studies were made and orders placed for the various proton-antiproton projects. The same applies for the water-cooling plants and the ventilation systems, which, particularly in LSS4 and LSS5, are complicated by the presence of large quantities of dangerous gases in the detectors.

4.3 Design office and workshops

The main activity of the design office this year was directed towards the realization of the new elements required for the projects.

The remotely controlled vacuum connections for NAHIF are being installed in the beam sections following the targets. They give full satisfaction.

The workshop worked under considerable pressure, particularly in connection with the repairs which followed the breakdowns of the septa in October.

4.4 Electronics services

The control cable installation work was maintained at a high level because of preparation for the project and the installation of the NAHIF area. Over 350 km of cable and 15 000 connectors were installed. The electronics workshop produced 200 chassis and 1600 modules. The printed circuit design office produced about two new designs per week and modified one existing board per day mainly on the QUEST system which continues to give reliable service. The documentation office produced more than 1000 new manufacturing drawings.

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The Personnel Protection Section rebuilt completely the original, temporary access system of the West Area to bring it up to the standard of the North Area. The North Area access system was extended to cope with new requirements.

The Communications Section must maintain about 50 TV beam observation stations, the wave-form switching system and the extensive sound and video distribution systems in the tunnels and experimental areas. The latter were extended during the year to keep up with the growing experimental program in the North Area.

4.5 Survey

The work was divided in almost equal shares between alignment and positioning of elements for all machines and transfer tunnels, the support to the experiments, and geodetical and support work for the various civil engineering projects.

Apart from these current activities, it is worthwhile mentioning the development of a laser interferometer with self-aligning reflector used for measuring distances, which suppresses the need for the rails of the classical systems.

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III. COMMON SERVICES DIVISIONS

- Division des Services techniques et Bâtiments - Division des Finances - Personnel Division - Health and Safety Division

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DIVISION PES SERVICES TECHNIQUES ET BATIMENTS

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DIVISION PES SERVICES TECHNIQUES ET BATIMENTS

1. INTRODUCTION

L'effectif de la Division a continué à décroître par le jeu des départs naturels et en l'absence de tout recrutement externe. En fin d'année, l'effectif sera de 540 personnes, très comparable à celui de juin 1968, alors que les charges de la Division ont été multipliées pendant cette période par un facteur voisin de 3, par suite de l'extension des sites et de l'accroissement correspondant des bâtiments et des installations.

La moyenne d'âge de 47 ans du personnel est supérieure de plus de 4 ans à la moyenne du CERN, et on note la présence de nombreux handicapés physiques. Toutes ces conditions réunies rendent nécessaire un appel à l'appui d'entreprises extérieures, avec les difficultés bien connues qui en résultent.

Dans toute la Division un très grand effort est fait afin de maintenir le programme dans les limites fixées pour l'effectif et le budget. Les risques qui peuvent en découler sur le plan de la fiabilité et de la sécurité du fonctionnement devront être acceptés si des mesures de renforcement et de rajeunissement du personnel ne sont pas rapidement prises.

Le budget de la Division en 1979 s'est élevé à 105 millions de francs suisses, répartis dans les grandes catégories suivantes:

Millions de francs suisses - Constructions 8,4 - Energie, eau 44,9 - Entretien, exploitation, transformations 25,5 - Ateliers centraux 13,8 - Transports, manutentions 10,1 - Direction et services fonctionnels 2,3

La dépense en énergie et eau représente la consommation des deux sites regroupée dans un même budget, alors que pour Prévessin cette dépense apparaissait au budget du SPS l'année passée (22,9 millions de francs suisses en 1978 pour le site de Meyrin seulement).

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Parmi les projets à l'étude ou en réalisation, on peut citer la mise en "stand-by" des groupes électrogènes, ainsi que le renouvellement du système de télésurveillance des installations générales ou le remplacement du système général de recherche de personnes.

4. ATELIERS CENTRAUX

La charge des Ateliers centraux, toutes activités réunies, est restée très élevée en dépit d'une situation rendue encore plus difficile par la réduction de l'effectif du personnel (- 10 personnes). Le montant des travaux en 1979 s'est élevé à 13,8 millions de francs, dont 5,3 millions de francs de travaux sous-traités. Le détachement de mécaniciens-monteurs dans les Divisions connaît toujours une grande faveur, et la demande est croissante sans qu'il soit toujours possible d'y faire face.

De nouveaux équipements à haute performance ont été installés: microscope à balayage et ses moyens d'analyse rapide, installation SCIAKY de soudage par faisceau d'électrons, fraiseuse MECOF à commande numérique, four DVM de traitement thermique sous vide.

Les études des Ateliers centraux ont porté sur un outillage spécial d'usinage des plaques du calorimètre (expérience UA2), des supports de têtes mécaniques sur coussin d'air, ainsi que des outillages pour les presses de 25 et 60 tonnes. Plusieurs équipements ont été modifiés ou agrandis. Le spectromètre hybride européen a bénéficié de ces travaux, notamment en ce qui concerne le détecteur de rayons gamma.

Pour le projet , des études ont été faites pour la modification d'une cavité haute fréquence avec une nouvelle chambre à vide et son système d'étuvage.

4.1 Section Contrôle-Qualité

La Section a effectué plus de 350 interventions de métrologie, 280 contrôles de matériaux et analyses de gaz, notamment pour les expériences UA1 et UA2. Les travaux de contrôle pour l'accumulateur d'antiprotons nécessiteront la mise à disposition de deux années-homme.

4.2 Section Circuits imprimés

L'activité a été très importante, en particulier dans le domaine des circuits de très grandes dimensions (longueur atteignant 2500 mm), qui sortent des standards que l'industrie privée exécute normalement. D'autre part, on constate la difficulté de confier à l'industrie les petites séries et prototypes dont le CERN a besoin.

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4.3 Section Traitement de surfaces

Nous ne citerons ici que quelques travaux parmi les plus délicats: dégraissage par solvant fluorochloré de plaques haute tension pour l'inflecteur MK 35, préparations avant brasage sous vide de pièces en cuivre usinées à l'outil diamant pour la structure HF de 800 MHz du SPS, revêtements d'or sur des embouts devant être sertis sur des fils de tungstène (expérience UA2), dépôts de cuivre sur des écrans HT en matière plastique (UA2).

4.4 Section Traitements thermiques

La charge de la Section a été très forte: dégazages sous vide d'enceintes en acier inoxydable et de ferrites (projet ), traitements de recuit sur cavités HF en niobium (avant-projet LEP), travaux de brasage sous vide d'une cavité accélératrice 800 MHz pour la Division SPS.

4.5 Section mécanique

Parmi les travaux importants réalisés, on peut citer: la fabrication de tanks à vide (projet ), de plaques pour aimants d'injection, d'écrans fixes et d'obturateurs, l'usinage de la chambre centrale du détecteur de l'expérience UA1, un élément pour essais du calorimètre de l'expérience UA2, l'usinage du bloc de détente et du palier hydraulique pour la chambre EHS-RCBC, la réalisation de chambres à vide pour les faisceaux M16 et K25 du synchro-cyclotron, ainsi que des pièces importantes pour la cavité 800 MHz de la Division SPS.

Les grandes machines ont toujours fonctionné à deux postes. Dans ce secteur très sollicité, les difficultés de personnel sont réelles.

4.6 Section Tôlerie-Soudure

Pour le projet , la Section a fabriqué quatre écrans statiques en acier inoxydable, de 2500 mm de long, par formage, assemblage et soudage (procédé (TIG), ainsi que deux poutres obturatrices en titane, assemblées puis soudées par bombardement électronique.

L'avant-projet LEP a demandé la réalisation d'une cavité en tôle de niobium de 2 mm d'épaisseur, par repoussage au tour de deux demi-coquilles qui, après plusieurs traitements thermiques intermédiaires, ont été soudées par faisceau d'électrons. Le diamètre de cette cavité est de 552 mm.

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D'autres travaux présentant de nombreuses difficultés techniques ont été réalisés: bobine coaxiale pour le condensateur rotatif du SC, fenêtre mince en acier inoxydable de 2100 mm de diamètre (parfaite tenue des soudures sous contrainte), chambre complexe pour source de rayons X.

4.7 Section des Services techniques

La Section s'est dotée d'un microscope électronique à balayage (SEM) et de ses accessoires. Les secteurs suivants ont été très sollicités: revêtements au pistolet et par évaporation sous vide, résines synthétiques, détecteurs (scintillateurs et guide-lumière), usinages de céramiques et de ferrites.

Des réalisations délicates ont été menées à bien: les cornes magnétiques (anneau AA du projet ), des éléments pour la source d'ions du SC, des barrettes de positionnement en alumine pour chambres à fils de haute précision (expérience NA11), des miroirs elliptiques pour compteurs Čerenkov (collaboration Mayence-ISOLDE), des éléments de chambres à fils constitués de feuilles de kapton, de 1 m de surface, sur les cotés desquelles une grille en cuivre a été déposée par évaporation sous vide au travers d'un masque (expérience W42), des compteurs à gerbes formés de sandwiches plomb/scintillateur (expérience R110).

En ce qui concerne l'avant-projet LEP, des travaux sur les traitements de surfaces du niobium ont été repris (cavités HF supraconductrices).

4.8 Section Ordonnancement et Sous-traitance

La Section, malgré le nombre réduit de son personnel, a coordonné environ 2400 demandes de travaux.

De nombreux et importants travaux ont été confiés à des firmes extérieures. Il faut citer, par exemple, le perçage et l'usinage de composants moulés de Stesalit pour l'expérience UA1 (montant sous-traité 550 000 francs suisses), des porte-ferrites, obturateurs, mécanismes divers, ensembles pour le tissage des chambres du détecteur central de cette expérience, circuits imprimés multi-couches.

L'activité a été très soutenue dans le domaine des contrats de petite mécanique et de fabrication de membranes souples, de traitement de surfaces, de peinture et de joints spéciaux. L'ensemble de ces activités extérieures représente une passation de 2500 commandes ou ordres de service pour un montant approximatif de 5,3 millions de francs suisses.

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5. TRANSPORTS, MANUTENTION, NETTOYAGE

Le parc des véhicules et engins du CERN s'élève à 618 unités, dont 101 véhicules utilitaires, 23 poids lourds, 13 tracteurs, 12 remorques, 66 élévateurs à fourche, 2 grues, 10 véhicules tous terrains, 12 engins de génie civil, 34 pour jardiniers et 43 autres pour la Section Nettoyage et les pompiers, ainsi que 302 voitures légères.

L'ensemble de ce parc est entretenu par les ateliers du garage du Groupe. Depuis juillet 1978, un nouveau contrat d'entretien partiel des véhicules du CERN fonctionne en donnant entière satisfaction.

Le transport de personnes a été beaucoup plus important cette année en raison du 25e anniversaire du CERN et de la Conférence de la Société européenne de Physique au Centre international des Conférences à Genève. Le Groupe a néanmoins assuré les transferts de matériels sur les sites et à l'extérieur sur de courtes et longues distances, en particulier les actions urgentes et délicates pour la physique, en plus des services généraux classiques.

On peut signaler, pour la manutention, les travaux particuliers suivants: installation d'aimants et de filtres neutrino, début d'installation pour projet (hall 193) et tunnel TT2A, l'arrêt des machines PS, ISR, SPS, SC et synchrotron injecteur, interventions dans le tunnel neutrino BA7.

La Section Nettoyage voit son activité en augmentation continue du fait de la prise en charge de nouveaux locaux, ceci avec un budget pratiquement constant.

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DIVISION PES FINANCES

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DIVISION PES FINANCES

1. SITUATION FINANCIERE

1.1 Cours des changes

Après la très forte hausse du franc suisse en automne 1978 et à la suite des interventions des banques centrales, la valeur du franc suisse a baissé sensiblement.

A part quelques fluctuations passagères en septembre et octobre 1979, principalement dues à la chute du dollar et à la flambée des prix de l'or, le cours du change du franc suisse s'est stabilisé cette année.

Le Tableau 1 montre la baisse du franc suisse par rapport à six monnaies d'Etats Membres pendant la période du 26 septembre 1978 au 31 octobre 1979.

TABLEAU 1

Monnaie Cours au 26.09.78

03.01.79

%

31.10.79 (par rapport au 26.09.78) %

FF 34,20 + 13,74 + 15,20 DM 77,10 + 15,56 + 19,58 Lit. 0,1820 + 7,69 + 9,90 £ 2,96 + 11,14 + 16,55 Sh.A. 10,64 + 14,37 + 20,30 Fl.H. 70,85 + 16,58 + 17,30

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1.2 Contributions

Le niveau des contributions reçues est de quelque 10 millions de francs inférieur à celui de l'année dernière à la même époque.

Le Tableau 2 donne la situation des contributions à recevoir au 31 octobre 1979.

TABLEAU 2

Etats Membres Programmes de base et ISR

FS Allemagne (Rép. féd. d') 492 309 Autriche 4 409 789 Belgique 7 989 283 France 38 005 886 Grèce 621 626 Italie 3 551 397 Norvège 1 592 943

TOTAL 56 663 233

1.3 Taux d'intérêts

Les taux d'intérêts étant en légère hausse, les recettes prévues au budget seront atteintes et même légèrement dépassées.

L'évolution des taux d'intérêts pour 1979 a été la suivante:

TABLEAU 3

03.01.79 %

01.04.79 %

01.07.79 %

01.10.79 %

1 mois - 1/4 7/8 1 2 mois - 1/4 7/8 1 3 mois - 3/8 1 1 5/8

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2. BUDGET 1980 ET DEPENSES PROBABLES 1979

Le projet préliminaire du budget 1980 aux prix de 1979 a été préparé pendant cette période, ainsi que le document CERN/FC/2304. Transferts et dépassements de crédits.

3. SERVICES FINANCIER ET COMPTABLES

La deuxième étape d'automatisation des paiments par chèques postaux suisses a été introduite avec succès au printemps de cette année.

Actuellement, on procède à des essais d'automatisation des paiements en francs suisses par banques, dont les premiers résultats sont encourageants.

Les études du nouveau système financier et comptable continuent.

4. SERVICES D'APPROVISIONNEMENT

L'année a été caractérisée par une intense activité dans le cadre du projet PROSAP. De très nombreux traitements et procédures ont été définis et le projet se trouve à un stade avancé du point de vue de la spécification des besoins.

4.1 Service des Achats

Au total, 77 appels d'offres et un nombre plus important encore de demandes d'offres ont été diffusés. Le nombre de ces dernières est passé de 1800, à la fin d'octobre 1976, à 2800 pour la même période de cette année. Le nombre des commandes et des factures est resté stable.

Le Service des Achats continue son effort de normalisation des tâches en établissant des textes standards dans tous les cas ou cela s'avère possible.

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Le Conseil norvégien de l'Exportation a organisé, avec la collaboration de 11 firmes nationales, une exposition dont l'objet était de faire connaître les possibilités offertes par l'industrie norvégienne et de les étudier en fonction des besoins du CERN. De telles manifestations contribuent à la diversification de nos sources d'approvisionnement et sont encouragées autant qu'il est possible.

Au cours de cette année, 59 firmes ont exposé les plus récents développements de leurs technologies dans le cadre d'expositions individuelles et itinérantes. En outre, 13 industries organiseront en novembre, durant deux jours, une exposition (dont un jour consacré à une table ronde entre exposants et groupe de travail CERN) sur le thème "système chassis Europa". Elle a pour objet de sélectionner les éléments qui conduiront à une normalisation plus poussée en matière de mécanique électronique.

4.2 Service des Magasins

Le nouveau système de distribution du matériel standardisé, introduit au début de l'année passée, fonctionne maintenant de façon satisfaisante. La valeur globale des sorties effectuées par les utilisateurs a considérablement diminué comparativement à l'année passée (14%). En revanche, la participation des self-services à l'ensemble du matériel sorti a doublé pendant l'année 1979.

La limite autorisée de la valeur des stocks a été portée à 14,8 millions de francs suisses par application de l'indice du matériel standardisé.

Le projet de la construction d'une nouvelle réception de marchandises a été approuvé et le début de sa réalisation est envisagé pour la fin de l'année.

Un nouveau système de documentation concernant les procédures d'exportation de matériel de la Suisse et utilisant une machine à photocopier programmée a été élaboré et introduit. A cette machine est couplée une deuxième machine programmée pour la duplication des commandes.

Le guichet Informations techniques a, en plus des nombreuses demandes d'information concernant le matériel standardisé, satisfait 6370 demandes urgentes de matériel.

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Pendant les neuf premiers mois de l'année:

- la valeur totale des sorties de matériel standardisé s'est élevée à 23 millions de francs suisses, soit une diminution de 14% par rapport à 1978; - la valeur des prélèvements de matériel dans les trois self-services a représenté 8,6% des sorties globales; - le taux de rotation annuel du stock central a été de 2; - la valeur du stock (central et self-services) a varié de + 10% à + 18% de la limite autorisée de 14,8 millions de francs suisses, le niveau moyen (à la fin de septembre) étant de 15% au-dessus de la limite autorisée;

- 40 087 arrivages, 8598 expéditions et 127 514 livraisons internes ont été traités et effectués pour l'ensemble de l'Organisation;

- 8442 demandes de livraison et commandes ont été établies pour le matériel standardisé;

- 219 500 demandes de matériel standardisé ont été traitées et prélevées du stock central.

Les Groupes de standardisation ont pris 805 décisions d'action. A la suite de ces décisions, 386 articles nouveaux ont été introduits en stock et 419 articles ont été déclassés, dont 308 articles d'une valeur de 115 300 francs suisses ont été transférés au Service de Récupération.

5. TRAITEMENT DES DONNEES ADMINISTRATIVES

L'application "Suivi des contrats" a été rendue disponible et améliorée en cours d'année. De même, un système simple d'interrogation de leurs fichiers mis à la disposition des Divisions est en constant développement. Des améliorations ont également été apportées au système PBS. Le sytème de paiement automatique des factures a été étendu.

Les travaux pour la définition du nouveau système financier, comptable et de gestion des approvisionnements, en liaison avec les moyens en matériel à mettre en place, se poursuivent.

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6. SERVICE PES ASSURANCES

La tenue à jour des divers portefeuilles d'investissement et la comptabilisation simultanée des transactions font l'objet d'un travail soutenu, dont le but est d'obtenir une situation réelle instantanée, pour faciliter la gestion des titres, dont le volume est croissant.

Les activités de la Caisse d'Assurances ont été marquées par un plus grand nombre de demandes de renseignements en relation avec l'examen de départs négociés et de rachats d'années d'affiliation. Le travail administratif lié aux prestations de la Caisse prend de plus en plus d'importance vu l'augmentation du nombre des bénéficiaires.

Dans le domaine des assurances en général, le Service a poursuivi ses tâches de révision et de mise à jour des contrats ainsi que de liquidation des sinistres de toutes catégories. Il s'est occupé, entre autres, des deux incendies survenus en avril et en juin de cette année et du règlement des deux cas de 1978.

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PERSONNEL DIVISION

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PERSONNEL DIVISION

1. The review of the employment and social conditions of the CERN personnel ("RESCO") created a heavy work-load for the members of the Personnel Division. Their tasks included conducting surveys, preparing documents on a wide range of financial and social aspects of employment conditions, and organizing and taking an active part in meetings where these questions were discussed. In addition, the review led to a special enquiry concerning various aspects of the CERN pension scheme.

The review is to conclude in the form of a report to the Finance Committee and Council, together with a revised edition of the Staff Rules and Regulations, for implementation in 1980.

In the meantime, a draft amendment to the health insurance contract, to protect family members against the economic consequences of invalidity, is under discussion with the insurance company.

A revised procedure on the subject of professional accidents and illnesses was drafted by an interdivisional working group and published. The group is extending its work to cover other questions, such as invalidity. It has been agreed in principle that an external medical advisor should be appointed to assist in these matters.

Two appeals against the Organization were addressed to the Administrative Tribunal of the International Labour Office. One case was settled out of court, and the other is still pending.

A start was made on defining and preparing for publication a comprehensive outline of "Organizational and Personnel Policy", and first discussions were held on the subjects to be included in the paper at the Executive Board, and within the Standing Advisory Committee.

The Division has participated in the elaboration of new staff strength planning and is providing regular information on future estimates of staff numbers in order to assist Divisions with their staff planning.

A recruitment action plan was drawn up and adopted so that Divisions could work towards the achievement of the future reduced personnel strength targets on the most efficient basis. As part of the personnel plan to rejuvenate the Organization while reducing the overall staff numbers, a system of negotiated departures designed to assist older staff wishing to leave was given prominence in the RESCO discussions, and a number of proposed measures were provisionally agreed to be implemented during the next three years.

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A review of the functions and assignments of 125 laboratory staff has been made in collaboration with the Experimental Physics Division in order to ascertain that the employment of this category of personnel is in accordance with the requirements of the Organization. The review took place in preparation for a change of contract status under which these persons would become staff members.

The number of unpaid associates increased by 20% over 1978, whilst the number of students dropped by 10%. The Summer Student Lecture Programme is shown under 2. hereafter.

At the request of the Advisory Committee of CERN Users ("ACCU"), a study was conducted on the accommodation needs of scientists staying at CERN for short periods. The result showed that the CERN hostel facilities on the Meyrin site should be extended, and that the accommodation standard of the hostel annex (barracks) should be improved.

A feasibility study was started concerning the possibility of handling reservations for the CERN hostel and furnished apartments, together with the Housing Fund accounts, by means of a mini-computer.

An extension of the Mail Office in the basement of the Administration Building has been completed, and the majority of the machines used in handling the mail are being installed there.

The messengers' rounds have had to be extended as new buildings have been brought into use, whilst staff limitations have resulted in a reduction in the number of rounds executed per day.

In an attempt to restrict the increase in the cost of official telephone calls, a number of public telephone cabines are being installed on the site, and the control circuits in the telephone exchange have been improved.

Approval was obtained for an extension to the restaurant facilities on the Prévessin site, and preparations were made in collaboration with the Site and Buildings Division. It is expected that the construction period will last several months during 1980.

The Personnel Division played a leading role in organizing and coordinating the arrangements for the 25th Anniversary Staff Day, held on the site on 29 September. Over 3000 members of the personnel, their friends and families enjoyed a wide range of activities: exhibitions by CERN clubs, races, games for the children, films, and dancing in the evening. A special ceremony was held for members of the personnel with 25 years' CERN service.

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Despite work-load related problems encountered in finding teachers internally, none of the courses proposed by the Technical Training Committee had to be withdrawn from the 1979-1980 programme. For the first time since the introduction of the current time-table system in 1973, over 300 CERN personnel were admitted to the courses. Several courses on computer science had to be duplicated; this was not possible in the case of other subjects, where applications had to be refused.

Detailed information about the courses is given hereafter.

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2. CERN SUMMER STUDENT LECTURE PROGRAMME

Particles and symmetries V.F. Weisskopf (8 lectures and 3 tutorials). Particle and nuclear physics at intermediate energies J. Bailey (2 lectures). The classical experiments which founded high-energy physics Ch. Peyrou (5 lectures4). Is the physical vacuum a medium? T.D. Lee (1 lecture). Electromagnetic and weak interactions D. Treille (1 lecture). Exploration of hadronic matter with electromagnetic and weak probes D. Treille (3 lectures). Search for new flavours D. Treille (3 lectures). A large neutrino experiment: why and how K.M. Mess (1 lecture). Bootstrap theory of particles G.F. Chew (1 lecture). What did we learn from the new particles L. Maiani (4 lectures). Antiprotons at CERN F. Bonaudi (2 lectures). What we hope to learn at the collider A. de Rujula (1 lecture) e+e- physics with LEP B. Wiik (1 lecture). High-energy physics and/in every day language R. Carreras (1 lecture). Introduction to particle accelerators E.G. Michaelis (4 lectures). Electronic detectors and nuclear instrumentation P.G. Innocenti (1 lecture), O. Ullaland (2 lectures), B. Heck (2 lectures), E.M. Rimmer (2 lectures), D.M. Sendall (2 lectures), all together (1 demonstration).

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Introduction to CERN's computing services C. Curran (1 lecture). High-speed computers T. Bloch (4 lectures). Radiation protection in accelerator environments G. Stevenson (1 lecture). Radiobiological considerations in radiation protection J. Baarli (1 lecture). The role of CERN in European high-energy physics J. Allaby (1 lecture). Particle accelerators and scientific culture U. Amaldi (1 lecture) Physics and society V.F. Weisskopf (1 discussion session). Student session L. Bettale, Ph. de Smedt, R. Färber (3 presentations).

(Average attendance: 120 (including 20 non-summer students); maximum: 220, minimum: 70)

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3. ENSEIGNEMENT TECHNIQUE (1978-1979)

22 cours ont été organisés totalisant 1528 heures d'enseignement (chaque séance comprenant 4 heures d'enseignement).

297 éleves ont été admis à suivre ces cours et 245 d'entre eux ont obtenu un certificat ou une attestation de fréquentation.

Cours Enseignants Nombre de séances

Mathématiques/Physique appliquée - Ateliers de mathématiques G. Charrière (D.I.P. - Service

de la Recherche pédagogique), C. Mercerat (E.T.S., Genève), J.P. Dufey (DD), L. Rinolfi (PS) K. Zankel (EF)

22

- Principes des détecteurs modernes

J.P. Lagnaux (I.I.S.N., Bruxelles) 15

- Techniques cryogéniques D. Robin (Université de Lausanne) 22 - Technologie et sécurité des gaz Ch. Nuttall (HS) 6 - Lois physiques et problèmes

énergétiques Ph. Dind (EPF, Lausanne) 15 - Les accélérateurs et leur

technologie K. Bätzner (PS) 15

Electronique - Initation à l'électronique

(2e année) J.J. Merminod (PS) 22 - Travaux pratiques

d'électronique S. Cairanti (EF) et P. Cennini (PS) 22

- Electronique analogique G. Baribaux (PS) 22 - Circuits et systèmes logiques B. Frammery (PS) 22 - Systèmes logiques programmés J.P. Vanuxem (EP) et

W. von Rueden (EF) 22

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Cours Enseignants Nombre de séances

Informatique - Initiation à l'informatique et aux

techniques de programmation (A) H. Slettenhaar (DD) et G. Ferran (DD) 22

- " " " (B) Y. Perrin (DD) 22 - Initiation au BASIC Y. Perrin (DD) et

H. Slettenhaar (DD) 10 - Systèmes d'exploitation de miniordinateurs

J.A. Bogaerts (DD) et A. Lacourt (DD) 22

- Introduction to microprocessors A Fucci (DD) et T. Lingjaerde (DD) 22

- Introduction to microcomputer programming A. Meier (Université de Genève) 15

Mécanique - Electromécanique J. Belleville (SB) et

A. Ranieri (SB) 22 - Initiation à la technique du vide R. Cornali (SPS) et B. Gay (PS) 6 - Techniques du vide B. Monnier (ISR) 12

Administration - Organisation des travaux

administratifs A. Brissonnaud (SB), A. Lecomte (SB), M. Wenner (FI) 12

- Eléments de statistiques V. Attarian (FI) et G. Lindecker (DG) 12

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4. COURS DE LANGUES (1978-1979)

DESCRIPTION DES COURS ANGLAIS FRANCAIS

DESCRIPTION DES COURS Nombre de cours

Nombre d'inscrits

Nombre de cours

Nombre d'inscrits

COURS EXTENSIFS (de 1 à 6 heures/semaine) 9 93 24 260

COURS EXTENSIFS SPECIAUX (entretien, phonétique, rédaction etc.) (de 2 à 6 heures/semaine pendant un maximum de 3 mois) 5 39 1 10

COURS SEMI-INTENSIFS (de 7 à 12 heures/semaine) 17 139 5 45

TOTAL 31 271 30 315

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5. ACADEMIC TRAINING PROGRAMME (1978-1979) 17 lectures series (63 lectures) Audience: max. 235 - min.5 Title of lecture series Lecturers Number of

lectures - Theory of perturbation of the point spectrum

W. THIRRING (University of Vienna) 2

- Programming methods and languages N. WIRTH (ΕΤΗ - Zürich) 2 - Precision limit of the cross-spectral density obtained by the fast Fourier transform of the cross-relation function. Application to signal recovery in noise.

A. KNOB (EPF - Lausanne) 2

- New quarks and their manifestations F. VANNUCCI (LAPP - Annecy) 4 - Phenomenology of weak interactions Μ.Κ. GAILLARD

(University of Paris XI) 4 - Techniques et expérimentations à très basse température (au-dessous de 1OK)

G. SCHUMACHER (CNRS - Grenoble) 5

- Parity violation experiments in atomic physics

V.L. TELEDGI (ΕΤΗ - Zürich and CERN) 4

- QCD for those who want to learn it seriously

C. SACHRADJA (CERN) 5

- Experimental review of high-energy neutrino physics

R. TURLAY (CEN - Saclay) 3

- Some aspects of the microstructure and thermal stability of dispersion alloys

P. COTTERILL (University of Surrey) 3

- Physics in Gottingen, Leipzig and Rome in the thirties

G.C. WICK (University of Columbia) 2

- Gravitational waves E. AMALDI and G. PIZZELLA (University of Rome) L. Radicati (Scuola Normale Superiore, Pisa) and E. Picasso (CERN) 5

- On practical non-parametric statistical methods

B. SCHORR (CERN) 4

- Minimization and the shape of the likelihood function

F. JAMES (CERN) 4

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Title of lecture series Lecturers Number of lectures

- The hadronic structure of the photon

D. YENNIE (Cornell University) 3

- An introduction to quantum mechanics

J.S. BELL (CERN) 5

- Ultra-high vacuum science and technology

C. BENVENUTI, R. CALDER, E. FISCHER, A. MATHEWSON and W. UNTERLECHNER (CERN) 6

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6. ENSEIGNEMENT GENERAL 1978-1979

"Science pour tous", par R. Carreras Cycle d'exposés destines plus particulièrement aux personnes n'ayant pas de formation scientifique. 32 exposés - Audience à chaque exposé: environ 200

Thèmes principaux:

1. La physique des hautes énergies aujourd'hui. 2. Collisions frontales entre noyaux d'uranium. 3. Radiations ionisantes, évolution des doses permissibles. 4. Les leptons. 5. Des neutrons enfermés dans une bouteille. 6. Membranes synthétiques. 7. Mois lunaires et mollusques fossiles. 8. Le mouvement relatif de la Terre par rapport à 1'"Espace". 9. L'apprentissage de la mémoire chez les abeilles. 10. Pions et radiothérapie. 11. Rayons cosmiques de très haute énergie. 12. Fonctions cérébrales et circulation sanguine. 13. Le problème des tectites. 14. Le thermostat des vertébrés. 15. Courants d'air, courants d'eau et êtres vivants. 16. La Galaxie M82. 17. Coups d'oeil sur l'évolution des accélérateurs. 18. A propos de l'origine du système solaire. 19. Les chimpanzés et le langage. 20. Arithmétique, papier quadrillé et réalité. 21. Vénus 1879-1979. 22. Le tau. 23. Les quarks.

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24. Traces de pas d'hominiens faites il y a 3,6 millions d'années. 25. Les yeux à miroirs. 26. Les nébuleuses gazeuses. 27. A propos de l'énergie nucléaire. 28. L'analyse des traces de fission. 29. Accélérateurs et production d'énergie. 30. Miroirs ardents. 31. La détection des substances mutagènes. 32. Le voyage de VOYAGER 1.

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7. APPRENTISSAGES (1978-1979)

Nombre d'apprentis de septembre 1978 à août 1979: 17

Profession 1e année

2e

année 3e

année 4e

année TOTAL

Employé de laboratoire en physique 2 3 3 - 8

Mécanicien-électronicien 3 2 2 2 9

Les 5 apprentis (3 employés de laboratoire en physique et 2 mécaniciens-électroniciens) qui ont terminé leur apprentissage en 1979 ont obtenu le Certificat fédéral de capacité.

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HEALTH AND SAFETY DIVISION

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HEALTH AND SAFETY DIVISION

1. RADIATION PROTECTION GROUP

In 1979 radiation protection was faced with a considerable increase of intensity in the main accelerator chain, linac, booster, PS, SPS and with an energy increase in the three main experimental areas of the SPS, the West Area (200 → 240 GeV) and occasionally the Neutrino and North Areas (400 → 450 GeV). The Radiation Protection Group continued all its activities but some slow-down and operational difficulties occurred owing to reduction in staff. The Group had the pleasure to welcome three physicists from the High-Energy Institute of the Academia Sinica of Peking. They will stay for one to two years in order to study radiation protection problems encountered in the design of the 50 GeV BPS planned to be built North of Peking. Studies on a new method for individual neutron monitoring and a muon (penetration) experiment to test predictions on muon transport were continued.

1.1 Radiation survey and control

At the North experimental complex of the SPS, all beam intensities were increased, resulting in higher levels of stray radiation and of induced activity. The SPS Survey Section had to cope with a growing number of measurements and interventions and with a considerable increase in work planning. The NAHIF project demanded assistance in the design and installation phase for all radiation-relevant problems. In addition, the construction work needed radiation assessment and surveillance. The SPS Survey Section was involved in the LSS4-LSS5 projects. In the SPS ring, radiation increased particularly in dump and ejection areas. Repairs due to radiation-induced damage became more frequent. In all experimental areas, in transfer tunnels, and in the SPS ring the radiation monitor systems were essential to control the radiation situation, which was acceptable, but most of the safety margin of the SPS design has been used up and operational control must now be tightened.

The West Survey Section (ISR, West Area, Neutrino) encountered more difficulties with the stray radiation levels. Although the shielding has been improved in some areas, operational changes offset some of these improvements. Radiation levels in the neutrino cave caused some problems.

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On the other hand, improvements on the remotely operated crane and the use of a manipulator helped in keeping personnel exposure down. The overall situation was about the same as in 1978. The Section was involved also in work planning and in the installation of a new monitor system and other improvements.

The work outside the West target station was completed and the shielding proved to be adequate. No particular problems in the target station are to be reported, which is a very good result for such a complicated installation.

Intensities increased at the ISR, but radiation and induced activity levels remained low. Self-service activity monitors (Picomur) are widely used, reducing the number of times radiation protection technicians have to be called.

Intensities increased also in the PS East Area, producing high induced-activity levels. The safety margin in the shielding thickness is almost exhausted. Careful proton beam operations and a vigilant monitor system are needed. The dose to personnel remained at about the 1978 level. Some breakdowns of equipment due to radiation were noted. The Section collaborated in the design of the AA project, surveyed construction sites (AA complex and TT70) and new beam areas, pursued its participation in radiation protection projects (new personnel neutron monitor, search monitor) and devoted much time to information meetings with staff.

The SC/Site Section collaborated in all phases of bringing the new heavy-ion beam into operation. The radiation protection work at the SC and nuclear chemistry continued and encountered many problems (protection against irradiated uranium targets, manipulation and transport of strong sources, interactions of heavy ions). The Section also dealt with radiation from sources other than high-energy accelerators, such as betatrons, X-ray equipment, fluorescent screens, and non-ionizing radiation.

The Section intensified and enlarged its area-monitoring programme using thermoluminescent detectors. It continued to prepare and provide radioactive sources and assisted with the site-monitoring programme.

1.2 Environmental monitoring

The environmental monitoring programme was continued over the whole of the CERN site. Small increases in gaseous activities released were registered. Radiation levels increased around the North Area and were constant elsewhere. Samples of water, aerosols and vegetation were measured in the central laboratory and the results of all environmental monitoring was reported at quarterly intervals to the authorities of the host countries.

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1.3 Personnel monitoring

The number of persons monitored individually by gamma films reached a plateau of about 4000 persons/month in 1979. The number of neutron films distributed increased steadily. A new system for the computer control of the film distribution, offering greater flexibility, was introduced.

1.4 Calibration

As in 1978, the statutory routine instrument calibrations represented the most important part of the Section's programme. However, acceptance tests, instrument assessment and selection play their role in the Section's tasks. Considerable support was given to the Radiobiology Research Group in the carrying out of irradiations in various high-energy particle beams.

1.5 Technical support

The installation programme of the Section comprised improvements and reinstallation of the West Area monitor system, the installation of radiation and air monitors in NAHIF, area monitors in the PS South Hall, and new monitors for induced radioactivity in the neutrino cave. Installations for LSS4 and LSS5 and for AA are being specified and equipment prepared. Most of the new data acquisition system (computer) has been installed in the central Radiation Protection building and all monitors on the Meyrin site are directly linked to the central computer via multiplex; a computer link to the SPS is available. Maintenance and repair of all instruments and systems of the Radiation Protection Group and technical assistance to other groups in the HS Division as well as improvements and development of instruments required a considerable effort.

1.6 General activities

The work on testing the radioresistivity of materials used in the accelerators was carried on, in particular that of material for new projects and for replacements. Two volumes of a comprehensive catalogue containing the results of all these tests were published.

The development of computer codes for hadron cascade calculation, in particular for electromagnetic interactions, continued in collaboration with visitors from other institutes and universities. Tests at the PS and SPS were made to verify some of these calculations.

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2. RADIOBIOLOGY RESEARCH GROUP

Basic studies of the biological effects of high-energy particle radiations were continued. Biological irradiations were made in two runs on the SC using the 600 MeV neutron beam and in an exploratory run using for the first time a 250 GeV hadron beam from the SPS.

High-energy neutron irradiations were part of a study being carried out in collaboration with the Paterson Laboratory (Christie Hospital and Holt Radium Institute, Manchester) to investigate the production of apoptosis in mouse intestine resulting from fragmentation of hypersensitive stem cells. The biological results show that doses as low as 0.5 rad produce detectable effects and that the relative biological effectiveness (RBE) of the neutrons appears to increase with decreasing dose. Another series of irradiations in the 600 MeV neutron beam were made for the study of chromosome aberrations formed in human blood lymphocytes. These investigations are part of a project carried out in collaboration with the Radiopathology Laboratory at CNEN (Rome) to look for special effects of high-energy particle interactions; the results will also provide information essential for the rapid assessment of possible biological damage following serious accidental overexposure.

Radiation effect studies using Vicia Faba bean roots as the biological test system were continued and included an investigation of dose-fractionation effects with 600 MeV neutrons. These experiments indicate that no recovery of the radiation damage takes place after high-energy neutron irradiation.

The Vicia Faba bean-root system was also used in a first study of the biological effectiveness of 250 GeV protons from the SPS, the results of which are now being analysed.

A considerable effort has been put into scoring the many cytological samples accumulated from previous experiments and analysing the data obtained. In particular, the production of micronuclei in Vicia Faba bean-root cells have confirmed that recovery occurs after irradiation with fast pions but is absent when the bean roots have been irradiated with stopped negative pions.

In addition, a collaborative experiment with CERN and Euratom was carried out at JRC Ispra in which beans were irradiated with low doses of neutrons of various energies. Although this experiment is not yet completed, the results tend to confirm that at very low doses the RBE approaches a value independent of the neutron energy used, as was found in previous investigations on eye-lens opacification.

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3. GENERAL SAFETY GROUP

The principal activity continued to be the systematic inspection of installations and equipment to identify potential hazards and prescribe precautionary measures, improved methods of work and the use of safety equipment. The system of channelling all matters of safety from each Division through a particular Safety Group representative has improved means of communication and collaboration in safety actions.

Emphasis was placed on the safety of contractors' personnel working on the CERN site. For major areas of construction, representatives from contractors, national inspectors and CERN are meeting on a regular basis to examine and act on matters of safety. Steps have also been taken to improve communications with firms contracting personnel to Divisions.

Among important experimental installations being followed from the design stage to operation are:

- project: buildings, tunnels and experimental installations; particular attention was paid to new safety problems associated with the use of inflammable gas mixtures in the underground experimental halls;

- EHS in hall EHN 1: rapid-cycling bubble chamber, superconducting magnet and other detectors;

- Marx generator and associated installations in hall 188;

- R807 experiment: 64 m3 Čerenkov counter for the ISR.

In day-to-day activities, actions against chemical pollution, control of toxic products, fire prevention and fire-risk analysis, mechanical tests and inspections, and accident investigations continued to play an important role.

A display of safety equipment available at CERN forms part of a permanent safety exhibition in the Safety Group building.

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Accident statistics for the period 1.10.78 to 30.9.79

Number of accidents reported 221 Number of disabling* accidents 76 Number of lost working days 2011 Disabling* accidents per 106 man-hours** 6.01 ± 0.68 Lost days per 103 man-hours*** 16

* A "disabling accident" is an accident causing an absence from work of one day or more in addition to the day on which it took place.

** This quantity is known also as the "frequency rate". *** This quantity is known also as the "severity rate".

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4. SERVICE MEDICAL

Les activités traditionnelles du Service médical se sont déroulées comme par le passé (examens médicaux systématiques, examens complémentaires, premiers soins a l'Infirmerie, etc.). Une attention toute particulière a été vouée aux personnes ayant accumulé des doses de radiations égales ou supérieures à 10 rem; aucune constatation anormale n'a été faite lors de ces contrôles. D'autre part, la surveillance systématique du personnel de la Division Physique expérimentale a pu être menée à bonne fin.

Une mise à jour des informations concernant les nuisances professionnelles auxquelles peut être exposé le personnel a été réalisée; on a ainsi pu recueillir des données actualisées, ce qui a permis une meilleure organisation de la surveillance médicale des groupes de personnes concernés.

5. SERVICES GENERAUX

Les Services généraux comprennent les sapeurs-pompiers/secouristes/gardiens, les techniciens des salles de conférences et les jardiniers.

De par leur nature même, ces trois Sections participent étroitement aux activités du CERN et elles ont été particulièrement mises à contribution en cette année 1979 qui a marqué les 25 ans d'existence de l'Organisation.

En effet, les sapeurs-pompiers et les gardiens ont été sollicités de différentes manières lors des nombreuses manifestations qui ont ponctué ce 25e anniversaire, et leur présence a été très appréciée. Par ailleurs, la fonction de surveillance a pris des proportions toujours plus grandes en raison de nouvelles constructions et des nombreuses expériences, surtout au SPS. Il en est de même des contrôles effectués sur tout le territoire du CERN ainsi que des interventions de la Section Incendie et Premiers Secours dont le nombre est supérieur à celui de 1978. Malgré un important surcroît de travail occasionné par cette année exceptionnelle, le Service a continué à contribuer efficacement à la prévention, base de la sécurité. Les cours de secourisme ont été poursuivis avec intensité.

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Les techniciens des salles de conférences ont participé d'une manière particulièrement active aux manifestations diverses du Jubilé: conférences scientifiques et communications diverses aux journalistes au CERN même, Conférence de la Société européenne de Physique au Centre international des Conférences à Genève du 27 juin au 4 juillet 1979, Conférence-exposition à Balexert, Genève, du 5 au 22 septembre 1979, Conférence ICFA aux Diablerets du 3 au 9 octobre 1979. Il convient, en outre, de rappeler leur collaboration technique aux séminaires, cours, colloques et conférences toujours plus nombreux et le fait qu'ils entretiennent et améliorent eux-mêmes les installations des salles de conférences ainsi que tout leur matériel.

Les jardiniers ont apporté une note fleurie au quart de siècle d'existence du CERN en apportant un soin tout particulier à la décoration florale des alentours du Bâtiment de l'Administration.

6. DIVISIONAL ACTIVITIES GROUP

In 1979, this Group of four people, dealing mainly with the information aspect of HS activities, continued the building up of the safety library and has made considerable headway with cataloguing the contents on an interactive computerized retrieval system. External specifications have been fixed for a computer-based distribution system designed to ensure that important documentation and information on safety matters is transmitted to those who whom it concerns.

Publication and distribution of a variety of safety-related documents has continued.

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IV. SERVICES OF THE DIRECTORS-GENERAL

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SERVICES OF THE DIRECTORS-GENERAL

The Services of the Directors-General comprise the seven units whose individual reports are given below:

Central Planning Office Council Secretariat External Relations Service Internal Audit Service Legal Service Press and Visits Service Translation and Minutes Service.

1. BUREAU CENTRAL DE PLANIFICATION

Ce Service a accompli les tâches suivantes dont il est chargé:

- établir en liaison avec les Divisions et proposer à la Direction les prévisions à court et moyen terme concernant l'utilisation des ressources financières de l'Organisation en fonction de son programme d'activités; contribuer ainsi à l'établissement des documents destinés au Conseil et à ses Comités qui ont trait aux prévisions de programmes et de budgets;

- suivre l'utilisation des ressources financières de l'Organisation par comparaison avec les prévisions suivant les programmes, les projets, les Divisions, en liaison avec les intéressés et avec l'assistance des autres services.

Par ailleurs, cette année le Service a:

- contribué aux travaux de définition du nouveau système de traitement des données administratives;

- publié le recensement des ressources consacrées en 1978 à la physique des hautes énergies en Europe.

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2. SECRETARIAT DU CONSEIL

Au cours de cette année, le Secrétariat du Conseil a assuré l'organisation matérielle de dix-neuf réunions de Comités et de deux sessions du Conseil. Entre le 15 novembre 1978 et le 15 novembre 1979, 144 documents en français, 199 en anglais et 76 en allemand, totalisant 4262 pages, ont été préparés et diffusés par ses soins.

Le Secrétariat a également organisé cinq réunions restreintes et deux réunions plénières de l'ECFA et préparé les documents y relatifs.

3. SERVICE DES RELATIONS EXTERIEURES

Le Service des Relations extérieures a poursuivi sa mission de contact avec les services publics français et suisses, au niveau tant local que cantonal ou départemental, national ou fédéral. Il a également assuré une liaison permanente avec les autorités locales suisses et françaises et les élus à tous niveaux. Le Service a également contribué aux préparatifs des cérémonies du 25e anniversaire.

Les contacts ont été plus particulièrement orientés, au cours des derniers mois, vers les représentants des populations du Pays de Gex ainsi que vers les responsables des diverses catégories socioprofessionnelles de la proche région française.

Le Service a poursuivi la gestion des parties du site français laissées à l'agriculture. Le Comité consultatif, créé en vue d'associer les représentants de la préfecture, les élus locaux et le représentant du syndicat agricole à l'examen des problèmes posés par l'implantation du CERN dans une région rurale, s'est réuni à deux reprises cette année. Des propositions pour l'aménagement forestier et l'amélioration des zones cultivées ont été faites et approuvées par ce Comité.

Pour le site suisse, le Service s'est attaché à élaborer, en liaison avec les autorités fédérales, l'Avenant NO 2 au Contrat de superficie, mettant à la disposition de l'Organisation les terrains pour la réalisation de sa mission scientifique.

Dans divers domaines des relations avec les services publics des deux Etats-hôtes, ont été plus particulièrement traités:

- l'harmonisation des législations et réglementations françaises et suisses applicables aux entreprises travaillant sur le domaine du CERN;

- la politique des contrats (participation au groupe de travail);

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- les relations avec les syndicats et les problèmes du droit du travail;

- le problème du passage par le tunnel et par la douane;

- le droit applicable sur le domaine de l'Organisation et la réforme du permis de construire;

- le système de recherche de personnes et la liaison avec les Directions générales des Télécommunications.

4. SERVICE DU CONTROLE INTERNE

Au cours de cette année, le Service du Contrôle interne a été amené à réformer certaines méthodes de vérifications appliquées jusqu'alors afin de les simplifier et en améliorer l'efficacité. L'accent a été mis sur l'utilisation des moyens informatiques par interrogation des bases de données existantes, notamment en matière de contrôle des marchés.

Par ailleurs, en liaison avec les Divisions et les Services généraux concernés, il a participé à l'étude des améliorations à apporter aux procédures administratives, en particulier à celles utilisées pour les appels d'offres et les marchés, ainsi qu'à la préparation d'une nouvelle codification budgétaire.

5. SERVICE JURIDIQUE

Le Service jurifique a préparé les documents et donné les avis demandés par les Directeurs généraux ainsi que le Directoire et pris part aux travaux du Conseil et de ses Comités.

Il a participé aux travaux du Groupe de travail RESCO, conseillé la Caisse d'Assurances, terminé le rapport du Groupe de travail chargé d'examiner les problèmes relatifs à la Caisse d'Assurances du CERN en cas de dissolution de l'Organisation, pris part à l'édition de la nouvelle réglementation de sécurité du CERN. Il a aussi participé à l'élaboration des actes se rapportant à l'activité de coopération internationale de l'Organisation.

Il a défendu les intérêts de l'Organisation devant les juridictions où elles comparaissait.

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6. SERVICE DE PRESSE ET VISITES

Les activités d'information et de relations avec le public ont connu pendant l'année une pointe due aux cérémonies du 25e anniversaire et aux discussions relatives au projet du nouvel accélérateur LEP. Le Service a ainsi:

- rédigé et diffusé quelque 30 communiqués de presse;

- reçu en moyenne chaque semaine un journaliste, une équipe de TV et un reporter radio ou un photographe;

- représenté l'Organisation à l'extérieur: Berlin, Paris, Bruxelles et Hambourg, ainsi qu'aux briefings hebdomadaires de presse dans les locaux de l'ONU;

- organisé un symposium de presse dans le cadre du 25e

anniversaire et reçu deux autres groupes de presse, (japonaise, norvégienne);

- tenu trois conférences de presse;

- organisé et conduit 30 visites de personnalités officielles, plus celles menées dans le cadre de la journée officielle du 23 juin;

- accueilli, avec l'aide de 87 "guides du samedi", quelque 10 500 visiteurs;

- poursuivi la direction du film "Une Expérience" qui devrait s'achever à la fin de 1981.

Ce qui précède reflète une augmentation du nombre des visites par rapport aux années précédentes et une plus grande "couverture" du CERN par les chaînes européennes de TV.

7. TRANSLATION AND MINUTES SERVICE

During the year under review, the working groups set up in previous years continued to hold a series of meetings, which entailed a considerable amount of translation work and minutes writing in addition to the normal tasks of the Service.

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