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ASYMMETRY MEASUREMENT of CHARGED HADRON PRODUCTION in pA 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, October 11, 2004

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20042

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С INTRODUCTION

Single spin asymmetry

of charge hadron ( , , p andp) 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.

ddddpA NN )(

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20043

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С POLIRIZED BEAM

60-70 GeV proton beam, 1013 ppp, hits Be target T. Produced neutral - hyperons are separated by magnet, following decay -+p collimator selects p.

The intensity of the polarized beam on the spectrometer target (T1) is 3107 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.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20044

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С DOUBLE ARM SPECTROMETER FODS

T1 – Target H – HodoscopeČ – Cherenkov counterS – Trigger counter DC – Drift chamberPC – Prop. chamber SCOCH – Ring imaging Cherenkov spectrometer HCAL – Hadron calorimeter STEEL – Muon detector MAGNET with beam dump inside

Spectrometer rotates around center of target.Two arms reduce systematic errors for symmetrical arm position.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20045

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СRING 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.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20046

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С 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

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20047

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С 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.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20048

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С PION PRODUCTION at CM~900

No difference for pC and pCu (pT ≤ 2.5 GeV/c).

pT-dependence has maximum at 1.2 GeV/c and minimum at 2.2 GeV/c.

First – data for pT ≥ 2.2 GeV/c.

First pA data.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 20049

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С KAON PRODUCTION at CM~900

No difference for pp, pC and pCu.

AN has maximum near 2.2 GeV/c.

First K+ data for pT ≥ 1.2 GeV/c.

First pA data.

Polarized u-quark from proton fragments into K+ or +.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

October 11, 200410

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С KAON PRODUCTION at CM~900

No difference for pp, pC and pCu.

AN ≈ 0 (no valence quarks from polarized proton).

First K– data at high energy and pT.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

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СNUCLEON 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.

First p data for pT ≥ 2.2 GeV/c.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

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СNUCLEON 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.

Asymmetry measurements of charged hadron production in pA collisions at 40 GeV, Kryshkin Victor

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СSUMMARYSUMMARY

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.