Abhay DeshpandeAPS-DNP 2003
Abhay Deshpande
RIKEN BNL Research Center
Measurement of single transverse spin asymmetry AN in forward neutron production
at PHENIX
(Experimental confirmation of longitudinally polarized proton beams at PHENIX)
APS-DNP 2003, Tucson AZAPS-DNP 2003, Tucson AZ
Abhay DeshpandeAPS-DNP 2003
RHIC Spin Physics Program
0 Production: A. Bazilevsky
Heavy Flavors
Prompt Photon
Gluon Polarization Quark Flavor polarization
Transverse single/doublespin physics
W physicsSeparate du/u , dd/d from
Dubar/u and ddbar/d
Longitudinal single spin physics
Sivers vs. Collins effects & physics of higher twists
Transverse single spin physicsPhenix-Local Polarimetry
Abhay DeshpandeAPS-DNP 2003
Relativistic Heavy Ion Collider
BRAHMS & PP2PP (p)
STAR (p)
PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 A, 300 s
GeVs
L
50050
onPolarizati%70
cms102 2132max
<<
×= −−
Spin Rotators
Partial Siberian Snake
Siberian Snakes
200 MeV Polarimeter AGS Internal PolarimeterRf Dipoles
RHIC pC Polarimeters
Absolute Polarimeter (H jet)
2 1011 Pol. Protons / Bunch = 20 mm mrad
RHIC accelerates heavy ions to 100 GeV/A and polarized protons to 100 GeV (250 GeV in future)
Abhay DeshpandeAPS-DNP 2003
Plan of rest of this talk……
• RHIC Spin Program• Relativistic Heavy Ion Collider (RHIC)
2001-2002• PHENIX local polarimetry R&D Run 2
2002-2003• PHENIX local polarimeter Run 3• Spin rotator commissioning• Spin monitoring during Run 3
• Summary
Abhay DeshpandeAPS-DNP 2003
Local Polarimeter at IP12 2001/2
• RUN-2: Neutron asymmetry observed in IP12 while testing a local polarimeter designed to look for 0, asymmetries:
• “Left-Right” asymmetry measured for different slices in :
Abhay DeshpandeAPS-DNP 2003
RUN 2 Neutron Asymmetry IP12
• Successful measurement of forward neutron asymmetry.
• Large asymmetry gives good figure of merit for local (PHENIX) polarimetry.
• Do not understand physics origin but large analyzing power
Y. Fukao et al., "Proceedings of the 15th International Spin Physics Symposium (SPIN2002)
Abhay DeshpandeAPS-DNP 2003
PHENIX Local Polarimeter 2003
～ 1800cm
10cm (±2mrad)
PHENIX Collision Point
Dx magnetBlue beam Yellow beam
beam
Zero Degree Calorimeter (ZDC)Tungsten-Fiber Sandwich5.1T, 149 X0 3 ZDCs each side
SMDShower Max Detector (SMD)Plastic Scint. strips (0.5cm x 3)10 and 15 cm long7 x 1.5cm columns8 x 1.5cm rows Read by Hamamatsu M16
Abhay DeshpandeAPS-DNP 2003
Run 3: Loc.Pol. Operation
• Energy/SMD strip Energy Deposit Profile hit position
determine left/right and up/down & on the plot• Max Amplitude at = /2, –/2
Left/Right asymmetry Transverse• Max Amplitude at = 0
Up/Down asymmetry Transverse radial• Flat curve No asymmetry Longitudinal
€
RA =σ L −σ Rσ L +σ R
€
Asym. =1
P⋅RA
Abhay DeshpandeAPS-DNP 2003
Spin Rotator Commissioning (I)
(Raw
Asy
mm
etry
) / (
bea
m
pol
.)
BLUE YELLOW
Max at = +/-/2 Transverse
Max at = 0 Transverse Radial ! Spin Rot PS wired wrong!
BLUE
YELLOW
Abhay DeshpandeAPS-DNP 2003
Longitudinal at last!
ø(Raw
Asy
mm
etry
) / (
bea
m
pol
.)
ø(Raw
Asy
mm
etry
) / (
bea
m
pol
.) BLUE YELLOW
Pbeam = 36% Pbeam = 37%
Abhay DeshpandeAPS-DNP 2003
How longitudinal were the beams?
PHENIX Local Polarimeter measures ST
1.03.19.02.34.97)( ++
−−=yellowSL
Up-Down vs. Fill No.Left-Right vs. Fill No.
222 ,1 radialTverticalTTTL SSSSS −− +=−=
0.05.09.04.13.99)( ++
−−=blueSL
Abhay DeshpandeAPS-DNP 2003
Summary
2002• Employing the accidental discovery of neutron
asymmetry (IP12, 2001-2) PHENIX local polarimetry was designed, constructed
2003• PHENIX spin rotators were commissioned• Longitudinal orientation of spin monitored• Stay tuned to A. Bazilevsky’s talk on 0 ALL
FutureUnderstanding the physics origins of this
asymmetry
