EUROEPAN HYBRID SPECTROMETER (EHS)

CERN/EF/EHS-CC/77-28 7 June 1977

Minutes of the Seventh Meeting of the Construction Committee (CC)

on 3 May 1977

Present: H. Desportes, P. Falk-Vairant, D. Giisewell, A. Minten (Chairman), L. Montanet, G. Neuhofer, R. Newport, F. Schmeissner, J. Thresher (invited)

I. APPROVAL OF THE MINUTES OF THE SIXTH MEETING

The Minutes of the sixth meeting of CC (CERN/EF/EHS-CC/77-25) are approved.

II. STATUS OF AGREEMENTS AND CONTRACTS

A. Minten reports on the project authorization for Part A of EHS, decided by the Executive Board of CERN on 7 April 1977. Questions raised by the board members concerned the coordination of the work of the ex-ternal laboratories, the status of Part B and C of EHS and the responsi-bility of CERN for the operation of the complete set-up.

F. Schmeissner summarizes the meeting of the Finance Committee on 28 April 1977, in which the cost sharing between CERN, RL and Saclay for RCBC and Ml was approved. In the short discussion only two questions were asked, one on contributions for EHS from other European laboratories and one on the decision power of the CERN-RL Steering Committee in fin-ancial matters concerning RCBC.

P. Falk-Vairant announces that the agreements on the EHS drift chambers became effective with the reception of confirming letters, written by W. Majerotto on 24 March 1977 for the "Institut fur Hochenergie-physik" of Vienna (HEPHY) and by A.N. Diddens on 28 March 1977 for the "Nationaal Instituut voor Kernfysica en Hoge-Energiefysica" of Amsterdam (NIKHEF). Both letters announce that the delivery schedule of the drift chambers may be delayed by some months, if it should turn out that the early delivery dates, given now, ~re not necessary in view of the general start-up schedule of the whole EHS. In addition, A.N. Diddens asks the CC to invite a member of NIKHEF to such meetings where aspects of - the . drift chamber construction are on the agenda.

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III. PROGRESS IN DESIGN AND CONSTRUCTION OF RCBC, Ml AND INFRASTRUCTURE

3 .1 RCBC

In addition to information given by R. Newport in a note on "Status of RCBC Design" (CERN/EF/EHS-CC/77-27), the following points are discussed:

- Recent trials of A. Herve for the fast camera wind-on mechanism, done with a so-called "Ferguson Drive" in magnetic fields up to 0.5 T and advance rates up to 15 Hz, are encouraging. However, a more powerful hydraulic motor and better cooling will be ne-cessary in order to obtain the design figure of 20 Hz;

- The main optical window of RCBC will probably have 96 cm of dia-meter and 17 cm of thickness; apparent track distorsions pro-duced by stress in the glass will not go beyond 10 µm;

- The enquiry amongst the EHS interested groups about the simpli-fied lay-out of the film data board did not lead to many comments; one of the mayor requests aims at more (than only 5) physics bits on the film.

3.2 H. Desportes discusses progress in the following fields:

- Conductor: the tender action of early March resulted in 6 valid offers, two at a very interesting price; the order will probab-ly be placed with the firm Airco very soon;

Winding plant: is ordered; delivery probably in October 1977;

Definition of coil position: will be assured by a stainless steel mandrel on which the double pancakes will be aligned.

3.3 Infrastructure

D. Giisewell presents first ideas on the use of hut space for electronics and control rooms; the problem of high heat dissipa-tion and magnetic stray field in these huts is evoked.

IV. THE AMSTERDAM MEETING ON DRIFT CHAMBERS (17/18 March, 1977)

G. Neuhofer gives a sl.llI!lllary of the discussions and concentrates on the following points:

- The results of the spectrometer simulation study of F. Bruyant and R. Plano will lead to some modifications in the original drift chamber specification; more calculations are necessary before final conclusions are possible; probably drift chamber modules of 4 planes will be sufficient, but all the planes would have inclined wires of different angle;

- For the decision on the choice of the read-out electronics (CERN "DTR" versus the new system under development at Vienna) an evaluation sequence is agreed, being based mainly on test performances (to be expected this summer), price of series pro-duction and long-term availability of components.

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A. Minten recalls that any decision for a new system to be ope-rated by CERN must be agreed upon by the EF/EP Electronics Coordination Board. G. Neuhofer is asked to contact P. Innocenti.

V. THE EHS PHYSICS WORKSHOP (4-6 April, 1977)

L. Montanet summarizes the discussions at this workshop, in which 23 user groups were represented. The aim was to understand basic expe-rimental possibilities of EHS. At the same time the status of the aero-gel Cerenkov cells and ISIS, as well as the final proposal for Part C of EHS, were presented and discussed. There was much interest in additio-nal features of RCBC, in particular a chamber body better suited for pho-ton beams and a high-resolution camera. The widespread interest in expe-riments with EHS may lead to an initial request of an annual production of 5 million pictures with RCBC.

P. Falk-Vairant points out that the interest in new features must not lead to any delay or cost increase with respect to the presently specified version.

J. Thresher says that RL would not be in a position to do any work on high resolution optics before 1979. Nevertheless, R. Newport hopes to carry out feasibility tests on RCVD at the end of the present experi-mental programme.

In reply to a question of P. Falk-Vairant, L. Montanet says that a polarized proton beam would be interesting for EHS, but need not be given any priority.

VI . THE PROPOSAL FOR PART C

L. Montanet presents the proposal for Part C, as it will be sub-mitted to the SPSC of 24 May 1977 (CERN/SPSC/77-44, SPSC/P 42/Add.3). The aim of this part of EHS is to achieve a complete hadron detection and to measure the energy of ~o with the same precision as charged se-condary hadrons. The IGD in front of M2 would be provided by a collabo-ration of Paris and Serpukhov, the FGD at the down-stream end of EHS by a collaboration of Heidelberg, Padova and Roma. The cost of the equip-ment is covered by these laboratories, but CERN would help in tests and installation and assume later the responsibility for operation.

P. Falk-Vairant stresses the need for electronics experts in both collaborations.

VII. NEXT MEETINGS

The dates of the two following meetings of the CC are modified and fixed as follows:

CC8 CC9 CClO

Tuesday, Tuesday, Tuesday,

June 21, 1977 October 4, 1977 December 13, 1977

at 9.30 a.m. at 9.30 a.m. at 9.30 a.m.

D. Giisewell