A'M' Davidenko, A'A' Derevschikov, V'N' Grishin, V'Y' Khodyrev, V'I' Kravtsov, Yu' A' Matulenko, Yu'

1

Single spin asymmetry measurements for inclusive
productions in reactions and at
70 and 40 GeV/c respectively

• A.M. Davidenko, A.A. Derevschikov, V.N. Grishin,
  V.Y. Khodyrev, V.I. Kravtsov, Yu. A. Matulenko,
  Yu.M. Melnick, A.P. Meschanin, N.G. Minaev, V.V.
  Mochalov, D.A. Morozov, L.V. Nogach, S.B.
  Nurushev, P.A. Semenov, K.E. Shestermanov, L.F.
  Soloviev, A.N. Vasiliev, A.E. Yakutin
• Institute for high energy physics, 142281
  Protvino, Moscow region, Russia

M.G. RyskinPetersburg nuclear physics
institute,188300 Gatchina, St. Petersburg,
Russia
2
Contents

• Beam parameters
• Polarized target
• Detectors
• Trigger and data acquisition system
• Data analysis and results
• Discussions
• Summary

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Scheme of SSA meas. in react.
Talk is based on the preprint IHEP 2004-21,
Protvino, 2004 and YaF. 67 (2004) 1520-1528.
4
PROZA beam parameters
5
Proza Polarized Target
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Detectors

• Three types of detectors were used
• Scintillating and Cherenkov counters.
• Two scintillating hodoscopes H1 and H2 with two
  planes each (x,y).
• 3. The electromagnetic calorimeters for measuring
  the position and energy of each photon.

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Trigger and Data Acquisition System
Two level trigger was used 0 level trigger (60
nsec) coincidence S1S2S3H (each plane of
hodoscopes) 1st level trigger (350 nsec) on
transverse Energy (independently for each EMC
with 1.1 GeV/c or 1.4 GeV/c thresholds). DAQ was
based on the computer CM-4/CM-1420 complex in the
case of pp-interactions (350 event rate, 2x107
events were accumulated during 10 days). MC68030
was used as the DAQ for pion-proton. The rate of
data taking was around 300 events and 1x108 were
accumulated for 30 days.
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Data Analysis and Results

• Data analysis consists of
• finding clusters with energy more than 300 MeV,
• Separation of the overlapping clusters
• Establishing the single photon shower by using
  the EMC calibration information (on electron beam
  of 26 GeV)
• Analysis of more than two photon events-use of
  the table mass value of neutral pion,
• Monte Carlo estimates the corrections to the
  reconstructed energy and coordinates of the
  photons.
• Calculation of the left-right asymmetry,
• Calculation of the false asymmetry.

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Reconstructed photon energy spectrum
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pT and xF correlation in TFR
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Two photons mass spectrum (p3Gaus)
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SSA at 40 GeV for reaction
13
Scheme of SSA measurements in reaction
at 70 GeV/c
Talk is based on the preprint IHEP 2004-22 and
YaF. 68 (2004) 1512-159
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Reconstructed photon spectrum
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Photon multiplicity in EMC1
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Mass spectra of photon pairs
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pT and xF correlations in CR
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Determination of the slope parameter
In good agreement with FODS data for charged pion
cross-section measurements (IHEP 84-88)
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Final result for asymmetry at
70 GeV, CR
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Discussions

• The general overview of the theoretical
  interpretations of our data at 40 and 70 GeV/c
  leads to the following conclusions
• Most of the theoretical models based on pQCD are
  not applicable to our energy range.
• There are several phenomenological models
  (orbiting quarks, Sivers and Collins mechanisms,
  high twist effects, etc) explaining some aspects
  of data but not all of them.

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Energy dependence of SSA for pp-interaction in CR
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SSA in CR for inclusively produced by p-and
beams
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The ChromoMagnetic String Model (CMSM)(Talk is
based on the preprint IHEP 2004-16)
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CMSM (continued)
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CMSM (continued)
H? 0.08 GeV2, ?1.1 GeV-1,  
Asymmetry is defined by relation    
w(x) is a weighting (or diluting) factor    
GeV/c.
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CSSM (Continued)
where ci is c 0.48, for c0 0.64 for
and c- 0.96 for .
Color factors CF 4/3, CA 3.
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Comparison to the CMSM in CR, pp int.(1)
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Comparison to the CMSM, PROZA (2)(data from
preprints IHEP 2003-21 and IHEP 2004-32)
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Comparison to the CMSM, BFR, (3)
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Comparison to the CMSM (4)
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Summary

• For the first time the asymmetry was measured in
  the polarized target fragmentation region for
  reaction
• For kinematical domain -0.8 lt xF lt -0.4, 1 lt
  pT(GeV/c) lt 2 AN-(13.8 3.8) , while in the
  region -0.4 lt xF lt -0.1, 0.5ltpT(GeV/c) lt 1.5
  asymmetry is compatible with zero, This is
  consistent with the E704 conclusion that
  asymmetry is zero in the CR and nonzero in the
  polarized proton fragmentation region
• There is an indication on the threshold like
  effect in asymmetry. Asymmetry starts up to be
  nonzero at the same momentum equals 1.7
  GeV/c in the c.m.s. of the incoming particles.

at 40 GeV/c.
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Summary (continued)

• Asymmetry measured in the CR is zero for region
  1 lt pT(GeV/c) lt 3 for reaction
• The results are similar to E704 data (200 GeV/c)
  and in contrast to the CERN data at laboratory
  momentum of 24 GeV/c J. Antille et al., Phys.
  Rev. Lett., B94 (1980) 523. RHIC jet target is
  an ideal tool to make more precise asymmetry
  measurements from 22 till 250 GeV at fixed target
  mode to solve this problem.
• The measured data are described by the CMSM
  fairly well.

at 70 GeV/c.