Spin physics program in the Spin physics program in the U70 polarized proton beamU70 polarized proton beam

A.N.Vasiliev (IHEP-Protvino)A.N.Vasiliev (IHEP-Protvino)

on behalf of the polar70 groupon behalf of the polar70 group

XI International workshop on high XI International workshop on high energy spin physicsenergy spin physics

(DUBNA-SPIN-05)(DUBNA-SPIN-05)

September 27 – October 1, 2005September 27 – October 1, 2005

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V.V.Abramov, S.I.Alekhin, A.S.Belov, V.V.Abramov, S.I.Alekhin, A.S.Belov, V.I.Garkusha, V.I.Garkusha,

A.V.Efremov, P.F.Ermolov, S.V.Ivanov, A.V.Efremov, P.F.Ermolov, S.V.Ivanov, V.I.Kravtsov, V.I.Kryshkin, A.V.Kubarovsky, V.I.Kravtsov, V.I.Kryshkin, A.V.Kubarovsky, A.K.Likhoded, V.V.Mochalov, S.B.Nurushev, A.K.Likhoded, V.V.Mochalov, S.B.Nurushev, A.F.Prudkoglyad, V.N.Ryadovikov, I.A.Savin, A.F.Prudkoglyad, V.N.Ryadovikov, I.A.Savin, Y.M.Shatunov, S.R.Slabospitsky, Y.M.Shatunov, S.R.Slabospitsky, L.A.Tikhonova,D.K.Toporkov, L.A.Tikhonova,D.K.Toporkov,

S.M.Troshin, E.F.Troyanov, M.N.Ukhanov, S.M.Troshin, E.F.Troyanov, M.N.Ukhanov, A.N.VasilievA.N.Vasiliev

BINR-Novosibirsk, JINR-Dubna, IHEP-Protvino, BINR-Novosibirsk, JINR-Dubna, IHEP-Protvino,

INR-Troitsk, MSU-MoscowINR-Troitsk, MSU-Moscow

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ContentsContents1.1. IntroductionIntroduction2.2. Acceleration of polarized protons at U70Acceleration of polarized protons at U703.3. Polarization in elastic scatteringPolarization in elastic scattering4.4. Single-spin asymmetries in inclusive Single-spin asymmetries in inclusive

processesprocesses5.5. Spin effects in strange hadron productionSpin effects in strange hadron production6.6. Measurement of quark transversity Measurement of quark transversity

distributions in a polarized protondistributions in a polarized proton7.7. Double-spin asymmetry in Charmonium Double-spin asymmetry in Charmonium

productionproduction8.8. ConclusionConclusion

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IntroductionIntroduction

A possibility to accelerate high-intensive polarized proton A possibility to accelerate high-intensive polarized proton beam up to 70 GeV at the IHEP U70 accelerator, extract it beam up to 70 GeV at the IHEP U70 accelerator, extract it from the main ring and deliver to several experimental from the main ring and deliver to several experimental setups is being studied now in Protvino.setups is being studied now in Protvino.

We propose to study a wealth of single- and double-spin We propose to study a wealth of single- and double-spin observables in various reactions using longitudinally and observables in various reactions using longitudinally and transversely polarized proton beams at U70. transversely polarized proton beams at U70.

March 1-2, 2005 – Workshop on polar70 at IHEP. March 1-2, 2005 – Workshop on polar70 at IHEP. Over120 people participated. The IHEP management Over120 people participated. The IHEP management

charged the charged the polar70 working group to prepare the report for SPIN-2005 polar70 working group to prepare the report for SPIN-2005 workshop in Dubna. workshop in Dubna.

Intensity up to 5x1012/spillEnergy up to 70 GeV

Polarized proton source up to 20 mA

Polarization up to 70%

Fight depolarization :One partial snake in BoosterThree partial snakes in U70 (snake strength W=/2=0.1-0.15, more ?)

Collaboration of the three institutes :Institute for High Energy Physics, ProtvinoInstitute of Nuclear Research, TroitskBudker Institute of Nuclear Physics, Novosibirsk

Snakes : 12 superconducting helicoidal magnets , length 0.6-0.7m, magnetic field 5-6 Tl (straight sections in U70 - 4.6 m) – [Shatunov’s report]

For extracted beams :

Polarimetry – elastic scattering in CNI region (polarized jet target) –[Nurushev’s report]

Accelerated polarized proton beam at U70

6

BRAHMS & PP2PP

STAR

PHENIX

AGS

LINACBOOSTER

Polarized Proton in RHIC

Pol. Proton Source500 A, 300 s

GeVE

cmsL

100

%45on Polarizati

102 2131max

Spin Rotators

Partial Siberian Snake

Siberian Snakes

200 MeV Polarimeter AGS Internal Polarimeter

Rf Dipoles

RHIC pC PolarimetersAbsolute Polarimeter (H jet)

2 1011 Pol. Protons / Bunch = 20 mm mrad

AGS pC Polarimeters

Strong AGS Snake

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Spin physics program in the U70 Spin physics program in the U70 polarized proton beam:polarized proton beam:

1. A1. ANN and A and ANNNN in elastic scattering [high p in elastic scattering [high pTT22]]

2. 2. Precision measurement of single-spin asymmetry Precision measurement of single-spin asymmetry in inclusive charged hadron production in inclusive charged hadron production in pp and in pp and pA collisions at different production anglespA collisions at different production angles

3.3. Miscellaneous spin parameters (A,DMiscellaneous spin parameters (A,DNNNN,A,ALLLL) in ) in hyperon productionhyperon production

4.4. Transversity in Drell-Yan muon pairsTransversity in Drell-Yan muon pairs

5. Double-spin asymmetry A5. Double-spin asymmetry ALL LL in Charmonium in Charmonium production (∆G/Gproduction (∆G/G gluon polarization through gluon polarization through 22 if gluon-gluon fusion is significant)if gluon-gluon fusion is significant)

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Elastic scattering ½ ½ Elastic scattering ½ ½ ->-> ½ ½ - ½ ½ - physics observables and physics observables and

amplitudesamplitudes

||||,

||,

||,

||,

||,

5

4

3

2

1

MMts

Mts

Mts

Mts

Mts

NA 4321*52 Im

4),(

sdtd

tsAN

non–flip

double flip

non–flip

double flip

single flip

NNA 4

*32

*152 Re2

4),(

sdtd

tsANN

9

AANN and A and ANNNN in elastic scattering in elastic scattering Big effects in the previous experimentsBig effects in the previous experiments

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Experimental setup SPIN@U70 at Experimental setup SPIN@U70 at IHEPIHEP

(channel 8 at U70)(channel 8 at U70)

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Measurements of Polarization in Measurements of Polarization in pp-elastic scattering at SPIN@U70pp-elastic scattering at SPIN@U70

Both particles, forward and recoil protons will be detected by Both particles, forward and recoil protons will be detected by scintillation hodoscopes (forward arm) and drift chambers (recoil scintillation hodoscopes (forward arm) and drift chambers (recoil arm).arm).

Beam intensity up to 10Beam intensity up to 101212 protons/spill. protons/spill.

Particle identification will be performed by Cherenkov counters Particle identification will be performed by Cherenkov counters and additionally by a time-of-flight technique in the recoil arm.and additionally by a time-of-flight technique in the recoil arm.

Accuracies to be achieved in the AAccuracies to be achieved in the ANN measurements : measurements :

- less than 1% for p- less than 1% for pTT22 up to 6 (GeV/c up to 6 (GeV/c22) for 200 hours at beam ;) for 200 hours at beam ;

- 3% for 10 (GeV/c- 3% for 10 (GeV/c22) and 6% for 12 (GeV/c) and 6% for 12 (GeV/c22) for 600 hours at ) for 600 hours at beam. beam.

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Single spin asymmetry in inclusive Single spin asymmetry in inclusive

pion productionpion production E704 result at 200 E704 result at 200

GeVGeVThere are several recent results ofThere are several recent results of

such a big asymmtery –such a big asymmtery –

1) E925 at BNL at 22 GeV1) E925 at BNL at 22 GeV

2) PROZA in Protvino at 40/70 GeV 2) PROZA in Protvino at 40/70 GeV

3) STAR at RHIC at 3) STAR at RHIC at s=200 GeVs=200 GeV

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Theoretical approaches to explain Theoretical approaches to explain big single-spin asymmetry in big single-spin asymmetry in

inclusive hadron productioninclusive hadron production Sivers: spin and k correlation in initial state (related to

orbital angular momentum?)

Collins: Transversity distribution function & spin-dependent fragmentation function

Qiu and Sterman (initial-state) / Koike (final-state) twist-3 pQCD calculations

Usually we have combinations of these three effects in a Usually we have combinations of these three effects in a particular experiment and special technics are required to particular experiment and special technics are required to separate them from observed asymmetries.separate them from observed asymmetries.

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FODS – Focusing double arm FODS – Focusing double arm spectrometer spectrometer (channel 22 at U70)(channel 22 at U70)

The channel shielding allows to get a beam intensity up to 1010 proton/spill, FODS setup up to ~109 proton/spill.

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Particle ID at FODSParticle ID at FODS

Hodoscope photomultipliersare used to detect the Cherenkovlight rings.

Charged hadron identificationin the momentum range of6 GeV/c ≤ р ≤ 30 GeV/c

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Single spin measurements which Single spin measurements which can be done at FODScan be done at FODS

* * Precise measurements of APrecise measurements of AN N in inclusive production of charged in inclusive production of charged pions, kaons, protons and antiprotons at hydrogen and nuclear pions, kaons, protons and antiprotons at hydrogen and nuclear targetstargets – – big xbig xTT, to separate , to separate PT and XF asymmetry dependence, the measurements at several angles are needed (might be done in the range of 10-1300 in c.m.)

* * AANN in symmetric hadron pair production in symmetric hadron pair production

symmetric pairs (symmetric pairs (++ --,etc. )– hadrons produced in the c.m. with ,etc. )– hadrons produced in the c.m. with about the same momenta and moving in the opposite sides;about the same momenta and moving in the opposite sides;

for these processes for these processes kT 0 and there is and there is no Sivers effectno Sivers effect;; if if АN ≠0 – possible explanation might be an orbital

moment ? * Polarization in elastic pp-scattering.

* AANN in Drell-Yan muon pairs in Drell-Yan muon pairs no fragmentation no fragmentation (q+q →l+l ) – no Collins effect, AN in р↑р might be significant if valence quark angular momentum might be significant if valence quark angular momentum

contributes, to suppress hadrons, additional absorbers in each arm will contributes, to suppress hadrons, additional absorbers in each arm will be installed)be installed)

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Spin parameters in hyperon Spin parameters in hyperon production production

* Miscellaneous spin parameters* Miscellaneous spin parameters (A,D (A,DNNNN,A,ALLLL)) inin -hyperon production -hyperon production

can be detectedcan be detected at the experimental setup SVD (channel 22 at U70).at the experimental setup SVD (channel 22 at U70).

* The mass spectra of * The mass spectra of -hyperons at SVD -hyperons at SVD

* More than 200,000 * More than 200,000 -hyperons were -hyperons were detected over one month of data takingdetected over one month of data takingwith a beam intensity of 0.5*10with a beam intensity of 0.5*1066 protons/sec. protons/sec.

* * -hyperons are very well detected in the beam-hyperons are very well detected in the beamfragmentation region where big spin effectsfragmentation region where big spin effectsare expected. are expected.

* Asymmetry in * Asymmetry in -meson-meson production production * Spin effects in strange hadron production - * Spin effects in strange hadron production - role of strange quarks in the spin structurerole of strange quarks in the spin structureof nucleon ? of nucleon ?

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Experimental setup SVDExperimental setup SVD

C1,C2-beam scintillation and Si hohoscopes; C3,C4 – target station and vertex Si C1,C2-beam scintillation and Si hohoscopes; C3,C4 – target station and vertex Si detector; 1,2,3 – drift tubes (tracking detector) ; 4 – proportional chambers (magnet detector; 1,2,3 – drift tubes (tracking detector) ; 4 – proportional chambers (magnet spectrometer);spectrometer);

5 – threshold Cherenkov counter; 6- scintillation hodoscope; 7 - 5 – threshold Cherenkov counter; 6- scintillation hodoscope; 7 - -detector -detector

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1/2 1/2

L L

+f1(x)

h1(x)

proton

proton’

quark

quark’

u = 1/2(uR + uL)u = 1/2(uR - uL)

q(x)

q(x)

q(x)

1/2 1/2

R R

1/2 1/2

L L

-1/2 1/2

R R

g1(x)

-

Structure functions

Parton model

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Transverse double-spin Transverse double-spin asymmetry in Drell-Yan pairs – asymmetry in Drell-Yan pairs –

transversity distributiontransversity distribution

• One of the first measurements of the transversity distributionOne of the first measurements of the transversity distribution hhqq

11(x,Q(x,Q22) ) of the valence quarks and sea anti-quarks in the of the valence quarks and sea anti-quarks in the transversely polarized protontransversely polarized proton ; ;

• Measure the transverse double spin asymmetryMeasure the transverse double spin asymmetry AATTTT in the in the Drell-Yan production of muon pairs ;Drell-Yan production of muon pairs ;

• Luminosity of pLuminosity of p↑↑pp↑ ↑ - interactions is about 10- interactions is about 103535 cm cm-2-2ss-1 -1

( compare to 10( compare to 1031 31 -10-103232 cm cm-2-2ss-1-1 for PAX at GSI or for RHIC) ; for PAX at GSI or for RHIC) ; • Existing “Neutrino Detector (ND)” setup at U70 – make Existing “Neutrino Detector (ND)” setup at U70 – make

absorberabsorber

smaller (5 m instead of 70m), put polarized target in front of smaller (5 m instead of 70m), put polarized target in front of the absorber and use the muon detector of the ND setup ;the absorber and use the muon detector of the ND setup ;

* * Acceptance for the Drell-Yan muon pairs is close to 100% . Acceptance for the Drell-Yan muon pairs is close to 100% .

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Transversity distribution in the Transversity distribution in the protonproton

* In proton-proton interactions one measures the product of * In proton-proton interactions one measures the product of two transversity distributions, one for a quark and one for two transversity distributions, one for a quark and one for antiquark (both in a proton). At U70 energies 50-70 GeV antiquark (both in a proton). At U70 energies 50-70 GeV one expects measurements at xone expects measurements at x11xx22 = M = M22/s =>/s =>

for 50 GeV, M=1.5-3 GeV/cfor 50 GeV, M=1.5-3 GeV/c22, x, x11xx2 2 = 0.02-0.09 ; = 0.02-0.09 ;

for 70 GeV, M=1.5-3 GeV/cfor 70 GeV, M=1.5-3 GeV/c22, x, x11xx2 2 = 0.015-0.06 => = 0.015-0.06 =>

this leads to the this leads to the constraint oconstraint onn the quark and antiquark the quark and antiquark proton content .proton content .

* The region 1.5 < M < 3 GeV/c* The region 1.5 < M < 3 GeV/c22 is free from resonances and is free from resonances and can be exploited to access can be exploited to access hhqq

11(x,Q(x,Q22) ) via Drell-Yan via Drell-Yan processesprocesses..

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Estimated number of Drell-Yan Estimated number of Drell-Yan eventsevents

For a beam intensity of 10For a beam intensity of 101111 p/spill at a polarized target p/spill at a polarized target andand

30 days at beam, the estimated number of the Drell-Yan 30 days at beam, the estimated number of the Drell-Yan muon muon

pairs to be detected by the ND setup is as follows :pairs to be detected by the ND setup is as follows :

Mass of Mass of -pair, MeV/c-pair, MeV/c2 2 number of DY events number of DY events

1.5 180,0001.5 180,000 1.75 50,0001.75 50,000 2.0 24,0002.0 24,000

For PolFor Polbeambeam = 0.7 and Pol = 0.7 and Poltargettarget = 0.8 with Dilution Factor =4, = 0.8 with Dilution Factor =4, the Athe ATT TT errors in these bins are expected to be in the range of errors in these bins are expected to be in the range of (2-4)%.(2-4)%.

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Transversity – experimental Transversity – experimental difficultiesdifficulties

• The scheme of the experiment is as follows –> polarized The scheme of the experiment is as follows –> polarized beambeam

interacts with polarized target , then absorber and finally interacts with polarized target , then absorber and finally muon detector to detect Drell-Yan muon pairs (beam-dump muon detector to detect Drell-Yan muon pairs (beam-dump experiment).experiment).

• The hadronic background can originate from decays of The hadronic background can originate from decays of charged pions and kaons before reaching the absorber and charged pions and kaons before reaching the absorber and from hadrons penetrating the material (punch-through). from hadrons penetrating the material (punch-through).

• The polarized target will be a major effort; with a 20cm long target, atThe polarized target will be a major effort; with a 20cm long target, at5T the requirement's on a magnet are severe. Also the energy 5T the requirement's on a magnet are severe. Also the energy generated by the beam at 10^11 p cm^-2 isgenerated by the beam at 10^11 p cm^-2 is > 1 joule/spill. The > 1 joule/spill. The microwave power required is also substantial ~40microwave power required is also substantial ~40 mW/gm, again mW/gm, again assuming 140 GHz -> 5 T. So assuming 140 GHz -> 5 T. So we we will need a very substantial will need a very substantial pumping system for the highest intensity beams.pumping system for the highest intensity beams.   

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Transversity – conclusionTransversity – conclusion

Kinematics in three Transversity projects (for Drell-Yan pair masses Kinematics in three Transversity projects (for Drell-Yan pair masses from 1.5 to 3 GeV/cfrom 1.5 to 3 GeV/c22 ): ):

1) RHIC(BNL) – > 1) RHIC(BNL) – > ττ = x = x11 x x22 = 0.004-0.02 ; = 0.004-0.02 ;

2) U70 – > 2) U70 – > ττ = x = x11 x x22 = 0.02-0.09 . = 0.02-0.09 .

3) PAX at FAIR(GSI) – > 3) PAX at FAIR(GSI) – > ττ = x = x11 x x22 = 0.07-0.3 ; = 0.07-0.3 ;

4) First results4) First results onon transversitytransversity from from hydrogenhydrogen andand deuteriumdeuterium are published byare published by

HHEERMES RMES andand COMPASS COMPASS. .

The different kinematics makes FAIR, RHIC and U70 The different kinematics makes FAIR, RHIC and U70 really complementary in the transversity measurements really complementary in the transversity measurements

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Longitudinal double-spin Longitudinal double-spin asymmetry in Charmonium asymmetry in Charmonium

productionproduction We propose to simultaneously measure the double-spin asymmetry We propose to simultaneously measure the double-spin asymmetry

AALLLL for inclusive for inclusive 2 , 2 , 1 1 and J/and J/ by utilizing the 70 GeV/c longitudinally by utilizing the 70 GeV/c longitudinally polarized-proton beam on a longitudinally polarized target.polarized-proton beam on a longitudinally polarized target.

Our goal is to obtain besides the quark-spin information also the Our goal is to obtain besides the quark-spin information also the

gluon-spin information from these three processes in order to gluon-spin information from these three processes in order to determine what portion of the proton spin is carried by gluons.determine what portion of the proton spin is carried by gluons.

Gluon contribution into the proton spin as well asGluon contribution into the proton spin as well as strange quarks and orbital momentum strange quarks and orbital momentum contributionscontributions - - worldwide studies at HERMES, worldwide studies at HERMES, COMPASS, RHIC, JLAB, SLAC.COMPASS, RHIC, JLAB, SLAC.

We propose a new experiment in this field – should be We propose a new experiment in this field – should be complimentary to the existing experiments.complimentary to the existing experiments.

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Physics MotivationPhysics Motivation

It has been determined, through polarized deep inelastic scattering

experiments, that the quarks alone can not account for the spin of

the proton (i.e. is less than 0.3

To account for the spin of the proton, either the gluons are polarized

and/or there are significant contributions to the protons spin from

the orbital motion of its constituents.

1

2

1

2G + L

Quark spin Gluon Spin Angular momentumProton Spin:

27

Requirements on beam intensityRequirements on beam intensity

Information about gluon polarization might be obtained through Information about gluon polarization might be obtained through simultaneous measurements of Asimultaneous measurements of ALLLL in inclusive production ofin inclusive production of 22 andand J/J/ . . This experiment was proposed at FermilabThis experiment was proposed at Fermilab ( (P838)P838) atat 200 200 GeV as a continuation ofGeV as a continuation of E704E704.. The Fermilab’s PAC The Fermilab’s PAC pointed out pointed out that physics is extremely interesting that physics is extremely interesting , , but an intensity of the but an intensity of the polarized proton beam from polarized proton beam from -hyperon decays was small – the -hyperon decays was small – the statistics would not be enough. The experiment was rejected. statistics would not be enough. The experiment was rejected.

In our new proposal for U70 we expectIn our new proposal for U70 we expect instead of instead of 2.7*2.7*110077/min/min ( (P838) to have up to 4 · P838) to have up to 4 · 101088 /min (factor 15!) /min (factor 15!)..

In this report we use some estimates for 70 GeV on the In this report we use some estimates for 70 GeV on the base of the estimates which were done for P838 at 200 base of the estimates which were done for P838 at 200 GeV. GeV.

28

Charmonium production Charmonium production mechanisms in hadronic mechanisms in hadronic

interactionsinteractionsThe hadronic production of the The hadronic production of the states involves states involves

three parton fusion diagrams : three parton fusion diagrams : (c)(c)

- gluon fusion- gluon fusion ((a)a);;- light quark annihilation - light quark annihilation (b)(b);;- color evaporation - color evaporation (c)(c).. (a) (b)(a) (b)

29

Parton distributions in protonParton distributions in proton

Parton distributions (at Parton distributions (at =3.5 GeV,=3.5 GeV,close to the masses of close to the masses of -states)-states) in the 70 GeV proton in the 70 GeV proton see Figure see Figure(Alekhin-2005)(Alekhin-2005) - - valence u-quarks (blue) ;valence u-quarks (blue) ; - - valence d-quarks(green);valence d-quarks(green); - - sea quark/antiquarks (red) ;sea quark/antiquarks (red) ; - - gluons (black)gluons (black)

Estimate shows that at 70 GeV Estimate shows that at 70 GeV the contributions of gluon-gluonthe contributions of gluon-gluonfusion and quark-antiquark fusion and quark-antiquark annihilation to produceannihilation to producecharmonium with a mass of charmonium with a mass of 3.5 GeV in pp-interactions are 3.5 GeV in pp-interactions are comparable.comparable.

30

Goals of the experimentGoals of the experiment

The goal is to measure double-spin asymmetry AThe goal is to measure double-spin asymmetry ALL LL with with the use of longitudinally polarized beam and target in the use of longitudinally polarized beam and target in the following processes :the following processes :

pp + p + p -> -> 22 + X + X и и pp + p + p -> J/ -> J/ + + XX

J/J/ + + ee++ e e- - ee++ e e- -

J/J/ (3096) (3096) JJPC PC = 1= 1---- 1 1 (3510) J(3510) JPC PC = 1= 1++++

2 2 (3555) J(3555) JPC PC = 2= 2++++

31

Double spin asymmetry ADouble spin asymmetry ALLLL

The measured experimental asymmetry is given by The measured experimental asymmetry is given by

AALLLL = = [ 1/(P[ 1/(PB B * P* PTTeffeff)] * [ I(++) – I(+ –)] / [ I(++) + I(+ –)],)] * [ I(++) – I(+ –)] / [ I(++) + I(+ –)],

wherewhere PPB B is the beam polarization, is the beam polarization, PPTT

eff eff – effective target polarization – effective target polarization ,, I(++) I(++) ,,I(+–)I(+–) are the number of events normalized to the incident are the number of events normalized to the incident

beam. beam. The helicity states The helicity states (++(++) ) and and ((+–+–) ) correspond tocorrespond to ( () ) andand (()) respectively respectively , , where arrows indicate the beam andwhere arrows indicate the beam and target spin direction in the laboratory system.target spin direction in the laboratory system.

Theoretical predictions of ATheoretical predictions of ALLLL mainly depend on two assumptions : mainly depend on two assumptions :1. gluon polarization 1. gluon polarization ∆G/G∆G/G and and2. charmonium production mechanism which defines2. charmonium production mechanism which defines  ÂLLLL

at the parton level (in parton-parton interaction)at the parton level (in parton-parton interaction)

32

Gluon polarization in different Gluon polarization in different

modelsmodels In the proposed experimentIn the proposed experiment х х ~0.~0.3, 3, where where ∆G/G∆G/G in different in different theoretical models theoretical models is in the range between is in the range between 0.15 0.15 and and 1 1..

In Gluon fusion model : In Gluon fusion model :

AALLLL (xF) = Â (xF) = ÂLLLL * [ ∆G / G (x * [ ∆G / G (x11) * ∆G / G (x) * ∆G / G (x22) ], where Â) ], where ÂLLLL = = --1. 1.

[Doncheski, Robinet] : [Doncheski, Robinet] : AALLLL is negative for is negative for 22 andand J/J/

In Colour evaporation model [Contogouris] AIn Colour evaporation model [Contogouris] ALLLL is positive for is positive for 22 and and J/J/

33

Experimental setup Experimental setup might be assembled at channel 24(former channel 7) at U70might be assembled at channel 24(former channel 7) at U70

Open geometry experiment. Open geometry experiment. Main partsMain parts : : electromagnetic electromagnetic calorimetercalorimeter, , proportional chambers proportional chambers, , trigger hodoscopetrigger hodoscope

34

Geometrical acceptance to detect Geometrical acceptance to detect at 70 GeV at 70 GeV

Simulations were Simulations were

made for 70 GeV :made for 70 GeV :

must be in themust be in the

lead tungstate arraylead tungstate array

and eand e++ee-- from the from the

J/J/ -decay are at -decay are at

any place in the any place in the

combined calori-combined calori-

metermeter

35

ElectromagneticElectromagnetic calorimeter calorimeter To separateTo separate 1 1 (3510 МэВ) (3510 МэВ) and and 22(3555 МэВ) (3555 МэВ) the energy the energy

resolution of the calorimeter is criticalresolution of the calorimeter is critical, , especially for decaying especially for decaying .. According to the decay kinematics ofAccording to the decay kinematics of 22 , the , the ’s are effectively ’s are effectively

detected at very forward angle detected at very forward angle ((<<10100 0 мрад). мрад).

If the calorimeter is placed atIf the calorimeter is placed at ~4.~4.5м 5м from the targetfrom the target, , the central the central part of the calorimeterpart of the calorimeter ( (fromfrom ~~1010 up to up to ~100 mrad~100 mrad) ) has to consist has to consist ofof 1140 1140 lead tungstate crystals lead tungstate crystals (2,8 (2,8××2,8 2,8 ×× 22 22 cmcm33) – ) – an array of an array of 34х34 34х34 with a hole of 2x2with a hole of 2x2 in the middle for non-interacted beam.in the middle for non-interacted beam.

To cover a big angle region from To cover a big angle region from ~~100 100 up toup to ~~200 200 mrad, we mrad, we need toneed to addadd 1875 Pb-glass counters with a cross section of 1875 Pb-glass counters with a cross section of 3,83,811 ×× 3,83,811 cmcm22 -an array of-an array of 50х50 50х50 with a hole in the middle ofwith a hole in the middle of 25х25 25х25 to to placeplace PWO-crystals.PWO-crystals.

Such combined calorimeter will cover the region ofSuch combined calorimeter will cover the region of 22 productionproduction ххFF from from 0 0 up toup to 0 0..4 (4 (see the next slidesee the next slide). ).

36

The xThe xFF-distribution of the accepted -distribution of the accepted

22--events.events.

37

1 1 / / 2 2 separationseparation Monte-Carlo for 200 GeV. Monte-Carlo for 200 GeV. The J/The J/ mass is reconstructed – the mass is reconstructed – the

ee++,e,e--

energies are measured by Pb-glass calorimeter, the angles are energies are measured by Pb-glass calorimeter, the angles are measured by the proportional chambers. measured by the proportional chambers. Resolution is Resolution is 75 75 MeV/cMeV/c22. . The momenta of e The momenta of e+ + and e and e-- are constrained to give exact are constrained to give exact

J/J/(3096 (3096 MeVMeV) ) mass by scaling the energies of emass by scaling the energies of e+ + and eand e--, while , while keeping the ekeeping the e++ e e-- angles unchanged. The e angles unchanged. The e++ee-- momenta thus momenta thus constrained are combined with the momentum of the constrained are combined with the momentum of the on the on the PWO to calculate the PWO to calculate the 2 2 mass. mass. Resolution (Resolution () is less than 10 ) is less than 10 MeV/cMeV/c22..

--

38

Proportional chambers and the Proportional chambers and the triggertrigger

The proportional chambers placed between the target and the calorimeter The proportional chambers placed between the target and the calorimeter serve to track eserve to track e++ and e and e- - particles and assure that there are no charged particles and assure that there are no charged tracks in the tracks in the direction. direction.

Trigger on J/Trigger on J/ with the p with the pTT signals of e signals of e++ and e and e-- . Super-blocks in calorimeter – . Super-blocks in calorimeter –

ppTT for super-block. The scintillator-pad hodoscope for super-block. The scintillator-pad hodoscope containing 100 pads is containing 100 pads is placed 3.3 m from the target ( 1 m in front of the EM calorimeter ) to tag placed 3.3 m from the target ( 1 m in front of the EM calorimeter ) to tag the charged particles. The size and position of each scintillator pad the charged particles. The size and position of each scintillator pad corresponds to each calorimeter super-block. corresponds to each calorimeter super-block.

The trigger requirements :The trigger requirements : - 2 or more electron candidates which have p- 2 or more electron candidates which have pTT (super-block) > 0.6 GeV (super-block) > 0.6 GeV and have hits on the corresponding separate scintillator pads;and have hits on the corresponding separate scintillator pads; - - рT (super-block) of the electron candidates being greater than 2.5 GeV.

88% of J/’s detected in Pb-glass and PWO calorimeters satisfy these requirements (see next slide).

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The pThe pTT correlation between e correlation between e+ + and and ee-- from from 22 decays decays

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Trigger rate and backgroundTrigger rate and background

** The trigger rate estimated by Monte-Carlo simulations isThe trigger rate estimated by Monte-Carlo simulations is

~ 2~ 20000 events/spill for events/spill for 6*6*101077 protons/spillprotons/spill (spill beam duriation is 2 sec) (spill beam duriation is 2 sec)..

~~ 35% 35% by electrons from by electrons from --conversion; conversion;

~ 65% from charged hadrons overlapped with ~ 65% from charged hadrons overlapped with ’s within the’s within the

super-block.super-block.

* * Background for J/- charged hadrons.

(hadron pairs – low masses; rejection by lateral(hadron pairs – low masses; rejection by lateral

shower profile )shower profile )

For For J/ background is ~ ~10%(hadrons and conversion electrons)For 2 background is ~~10% ( J/ + fromfrom 0 0 )) see Figure see Figure

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Expected sensitivity in AExpected sensitivity in ALL LL for for charmoniumcharmonium

The The Р838 Р838 estimate wasestimate was1640 1640 2/month and 9200 J/ month for a beam intensity of 2,7*107 protons/min.

Assuming factor 1/3 in cross section decrease (from 200 GeV down to 70 GeV) and factor 15 in intensity rise, the overall merit factor is 5. We expect 8200 2/month and 46000 J/ /month .

We expect to get a precision of (ALL) = 0.075 for 2 and 0.025 for J/ for one month of data taking.

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Conclusions Conclusions To accelerate the polarized proton beam in the existing U70 up to To accelerate the polarized proton beam in the existing U70 up to

70 GeV with intensity up to 5*1070 GeV with intensity up to 5*101212 protons/spill and polarization protons/spill and polarization up to 70%, the following main tasks need to be completed :up to 70%, the following main tasks need to be completed :

- polarized proton source up to 20 mA ;- polarized proton source up to 20 mA ; - one snake to be installed in the 1.5 GeV booster ;- one snake to be installed in the 1.5 GeV booster ; - equipment from three straight sections (4.6 m each) to be - equipment from three straight sections (4.6 m each) to be

removed;removed; - three partial snakes to be installed in the U70 main ring ;- three partial snakes to be installed in the U70 main ring ; - correction of the U70 vertical orbit down to - correction of the U70 vertical orbit down to ±1 mm±1 mm;; - absolute (polarized jet target) and relative polarimetry. - absolute (polarized jet target) and relative polarimetry.

Acceleration of the pAcceleration of the p beam at U70 gives a brand new opportunity beam at U70 gives a brand new opportunity for high energy spin physics in the new kinematic region. The for high energy spin physics in the new kinematic region. The presented spin program includes five miscellaneous sets of presented spin program includes five miscellaneous sets of measurements :measurements :

- polarization in elastic scattering ;- polarization in elastic scattering ; - single spin asymmetry in inclusive charged hadron production ;- single spin asymmetry in inclusive charged hadron production ; - miscellaneous spin parameters in hyperon production ;- miscellaneous spin parameters in hyperon production ; - transversity in Drell-Yan muon pairs ;- transversity in Drell-Yan muon pairs ; - double-spin asymmetry in charmonium.- double-spin asymmetry in charmonium.

The results will be complementary to those which might be The results will be complementary to those which might be obtained at COMPASS, HERMES, RHIC, JLaB, GSI and JPARC.obtained at COMPASS, HERMES, RHIC, JLaB, GSI and JPARC.