Docstoc

University of Illinois at Urbana Champaign

Document Sample
University of Illinois at Urbana Champaign Powered By Docstoc
					                     measurements
                          at




   RHIC/AGS Annual Users’ Meeting
     Transverse Spin Workshop

K. Oleg Eyser
University of California, Riverside


June 6, 2006
                              Transversity

                                    (Sivers effect)
                               transversely asymmetric                  (Twist-3)
      (Collins effect)           kt quark distributions              quark gluon field
        spin-dependent
                                                                       interference
  fragmentation functions




                                       SSA
                             single spin asymmetries


           E704, BELLE, BRAHMS, COMPASS, HERMES, STAR, and PHENIX?

O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX                       2
                                       RHIC
                                                                     CNI Pol



                                          RHIC                       BRAHMS
           PHENIX
                                                                      STAR


             OPPIS


              Linac

               AGS


                 
                 
O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX             3
                                   PHENIX




O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX   4
                                   PHENIX




O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX   5
                 Forward Neutron Asymmetries
                                                    IP12’s first            AN = 0.110±0.015
 Zero Degree Calorimeter
 behind Dx magnet                                   asymmetry                             preliminary
 neutron  shower max

                                                            
                                 N left  N right  N left  N right
                            
                                                            
                                 N left  N right  N left  N right

                                   local            vertical polarization               radial polarization
                            asymmetries
                              at PHENIX
                                    /P

 monitoring of
 polarization alignment
 when using spin rotators                                               rad                                rad 


O. Eyser --- June 6, 2006         Transverse Spin measurements at PHENIX                                            6
                                     h+/- and 0
                                                                         data set
                                                                         eight weeks 2002
                                                                         L = 0.15 pb-1, P  15%
                                                                         three days 2005
                                                                         same statistics, P  47%




                                                charged hadrons
                                                central magnetic field
 neutral pions ()                            drift chamber
 calorimeters     0.01 0.01              vertex
 shower shape                                   track quality
 charged track veto                             DC zed position
 mass width 13.2 MeV - 10.6 MeV                 RICH nPMT
 combinatorial background 35% - 5%              PC matching

O. Eyser --- June 6, 2006      Transverse Spin measurements at PHENIX                               7
                                 Cross Sections
                                             in good agreement with NLO pQCD
                            0               over 5-8 orders of magnitude




O. Eyser --- June 6, 2006        Transverse Spin measurements at PHENIX        8
                                    Raw Asymmetries




                            efficiency (left / right)
                            luminosity (P / P)
                            acceptance (pt / charge / left / right)




O. Eyser --- June 6, 2006                Transverse Spin measurements at PHENIX   9
            Inclusive Single Spin Asymmetries
                            [Phys. Rev. Lett. 95, 202001 (2005)]
                                                                                   0 (2001/02)




                                                                                                       pt (GeV/c)

                                                                                      0     AN  rAN
                                                                                              peak   bg

                                                                pt (GeV/c)          AN     
                                                                                                1 r

 P=15% in 2002, P=47% in 2005                                          cross checks:
 polarization scaling uncertainty: 30%(2002), ≈                        left / right raw vs. efficiency-corrected
 20%(2005)                                                             /  raw vs. luminosity-corrected
 residual polarization in unpolarized beam:                            bunch shuffling, bunch fitting
             < 10% and small AN
O. Eyser --- June 6, 2006             Transverse Spin measurements at PHENIX                                       10
                                          J/
   gluon dominance                                dN        K M             
                                                                                ( M M J /  )2
                                                                                                                
                                                                                                                    ( M  M ' )2
                                                                                                                           

                                                      Ae         N  2  e 2               N '  2 1  e
                                                                          1             2                               2 2

   minimized Collins                              dM
   Sivers
    AN(0)
   di-muon decay
   (M. Liu, H. Liu)

   muon spectrometers
     forward rapidities
   for vertical and
   radial polarizations

                                            gg
   run5 --- 0.15 pb-1
    8% measurement
                                                        qq
   run6 ---     3.3pb-1                                                                                 m (GeV)
    few percent
                                                                      Anselmino et al.[hep-ph/0407100]


O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX                                                                 11
           Two-Jet Back-to-Back Correlations
 D. Boer and W. Vogelsang, Phys. Rev. D 69, 094025 (2004)

                                      ˆ                                          ST  ( P  k  )
                                                                                       
                                      f ( x, k , ST )  f ( x, k )   f ( x, k )
                                                                         1   N
                                                                         2
                                                                                  | ST || P || k  |

                                                         ()    ()
                                                   AN  
                                                        ()    ()

              ST        0  
     k
                                                          N g ( x)  0




                                                                               N g ( x)  N d ( x),   k 2  2.5GeV
          h

O. Eyser --- June 6, 2006         Transverse Spin measurements at PHENIX                                                12
         Two-Hadron b2b Correlations in PHENIX
                                                                  Run03 -charged dn/d
                                                                                   anti-aligned
                                                                                   aligned




                                          h  
                                                                             BV (iv)
                                                                             resolution smearing
  direction of central arms
   radial polarization
  radial polarization component in run5
  blue 8%, yellow 15%
  (J. Lajoie)
  statistical uncertainty in far peak  5%
  run6: 4 weeks with radial polarization
  recorded data: 3.3 pb-1 at P = 55%

O. Eyser --- June 6, 2006        Transverse Spin measurements at PHENIX                            13
       zero degree calorimeter
                                                   PHENIX Acceptance




                                                                                 zero degree calorimeter
                                                   EMCAL

                                                           muon arm
                                        muon arm


                                                   EMCAL
                                 FCAL




                                                                          FCAL




                                                                                                           muon piston calorimeter


O. Eyser --- June 6, 2006                                       Transverse Spin measurements at PHENIX                               14
                   The Muon Piston Calorimeter

                                                     foreground
                                                     mixed




                                                     background
                                                     subtracted




                            (M. Chiu: Overview of PHENIX Upgrades, Plenary Session IV, June 9)

O. Eyser --- June 6, 2006         Transverse Spin measurements at PHENIX                     15
                                         Outlook
    • run6
         (A. Deshpande, plenary session II, June 8)


    •    radial polarization > 55%
         integrated luminosity 3.3 pb-1
         (even more for longitudinal polarization)

    •    two-hadron back-to-back correlations
         central arms
         including forward region 3 <  < 4

    •    single spin asymmetries
         neutral pions in forward region
         J/  in the muon arms
         central arms (acceptance scaling  1 / 2.4)

    •    run7 ?

O. Eyser --- June 6, 2006        Transverse Spin measurements at PHENIX   16
                                  Summary
    • no finite single spin asymmetries in PHENIX central arm so far
      run2 and run5
      small systematic errors (bunch shuffling, buch fitting)
      constraints on Sivers?
    • analysis of two-hadron back-to-back asymmetries
      first look with residual polarization
      mid-rapidity (central arms)
      forward region
    • large negative forward neutron asymmetry
      backward asymmetry consistent with zero
      polarization alignment monitoring

    • increased acceptance for hadron analyses
    • run6 data set with considerable radial polarization



O. Eyser --- June 6, 2006   Transverse Spin measurements at PHENIX     17