ASYMMETRY MEASUREMENT of CHARGED HADRON PRODUCTION in p  A COLLISIONS at 40 GeV

1. ASYMMETRY MEASUREMENT of CHARGED HADRON PRODUCTION in pA COLLISIONS at 40 GeV Abramov V., Goncharov P., Kalinin A., Khmelnikov A., Korablev A., Korneev Yu., Kostritskii A., Krinitsyn A.,Kryshkin V., Markov A., Talov V., Turchanovich L., Volkov A. 16th International spin physics symposium, Triest, October11, 2004

2. INTRODUCTION Single spin asymmetry of charge hadron ( , ,p andp) production by 40 GeV proton beam with 40% transverse polarization off nuclei (С, Сu) was measured by FOcusing Double Arm Spectrometer (FODS). The measurements were carried out for hadrons with high xT(900 in c.m.s) and with high xF (one arm at 70 mrad and the other arm at 250 mrad). The results are presented for high xT processes. October 11, 2004

3. POLIRIZED BEAM 60-70 GeVproton beam, 1013 ppp, hits Be target T. Produced neutral- hyperons are separated by magnet, following decay -+p collimatorselects p. The intensity of the polarized beam on the spectrometer target (T1) is 3107 ppp, spill 1.3 sec, p=40 GeV/c, p/p= 4.5%, the transverse polarization 40%. Polarization direction is reversed each 18 min (takes 30 sec) to minimize time–dependent drifts in apparatus. Vertical magnets fix beam position on the T1 .+contamination ≤ 1.5 %.Beam monitoring – S, IC (intensity), Č (composition), IC, HB (trajectory).Targets – LH -0.05 int; C and Cu – 0.1 int. October 11, 2004

4. DOUBLE ARM SPECTROMETER FODS T1– Target H– Hodoscope Č– Cherenkov counter S– Trigger counter DC– Drift chamber PC– Prop. chamber SCOCH– Ring imaging Cherenkov spectrometer HCAL– Hadron calorimeter STEEL– Muon detector MAGNETwith beam dump inside Spectrometer rotates around center of target. Two arms reduce systematic errors for symmetrical arm position. October 11, 2004

5. RING IMAGING CHERENKOV SPECTROMETER Cherenkov light is focused by spherical mirror Ø 110 cm, conical mirror, 24 cylindrical lenses on photocathods of 24 hodoscopical photomultipliers (HPM). The radiator is Freon-13 at 8 atm. October 11, 2004

6. REGIONS of MEASUREMENTS Region 1: –0.25 ≤ xF ≤ –0.05 1.4 ≤ pT ≤ 3.2 GeV/c Region 2: (this report) –0.15 ≤ xF ≤ +0.20 0.5 ≤ pT ≤ 4.0 GeV/c Region 3: +0.05 ≤ xF ≤ 0.70 0.2≤ pT ≤ 2.5 GeV/c 10.6 106 hadrons in central region 2 October 11, 2004

7. PION PRODUCTION at CM~900 No difference for pC and pCu. AN (pp) < AN(pA) for pT ≤ 2.2 GeV/c. Indication of structure in pT-dependence with maximum at 2.2 GeV/c and minimum at 2.9 GeV/c. First+ data for pT ≥ 2.2 GeV/c. October 11, 2004

8. PION PRODUCTION at CM~900 No difference for pC and pCu (pT≤ 2.5 GeV/c). pT-dependence has maximumat 1.2 GeV/c and minimumat 2.2 GeV/c. First– data for pT ≥ 2.2 GeV/c. First pA data. October 11, 2004

9. KAON PRODUCTION at CM~900 No difference for pp, pC and pCu. ANhas maximum near 2.2 GeV/c. FirstK+ data for pT≥ 1.2 GeV/c. First pA data. Polarized u-quark from proton fragments into K+or +. October 11, 2004

10. KAON PRODUCTION at CM~900 No difference for pp, pC and pCu. AN ≈ 0 (no valence quarks from polarized proton). FirstK–data at high energy and pT. October 11, 2004

11. NUCLEON PRODUCTION at CM~900 No difference for pC and pCu. AN(pp) < AN (pA) for pT ≤ 3 GeV/c. AN(pA) ≈ 0. No structure for pT-dependence. Firstp data for pT≥ 2.2 GeV/c. October 11, 2004

12. NUCLEON PRODUCTION at CM~900 No difference for pp, pC and pCu. AN ≈ 0 (no valence quarks from polarized proton). pT-dependence has no structure. Firstp data. October 11, 2004

13. SUMMARY • pT–dependence of AN for +, – and K+ shows oscillation in central region for pp, pC and pCu collisions. AN reaches maximum and then drops to zero or even changes its sign. • First data for K– and p show zero AN for pp, pC and pCu collisions as expected due to absence of valence quarks from polarized protons. • AN for protons in pC and pCu collisions is consistent with zero within the experimental errors. • Data processing for polarized proton fragmentation region is under way. October 11, 2004