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Spin Physics at RHIC PHENIX
1. Physics Motivation
2. Accelerator and Detector
3. Result from Run2/Run3
4. What we can do?
Atsushi Taketani
RIKEN
RIKEN Brookhaven Research Center
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 2
Physics Motivation
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 3
Spin Structure of the Nucleon
q
q
g
u
u
d
pWhat is the origin of the Nucleon Spin?
1/2=(1/2)+G+LQ+LG
By Deep Inelastic Scattering Experiment : Quark Spin ~ 0.2-0.3 G : Gluon Spin~ 0 - 2
LQ,LG : Orbital angular momentum ~ ?
Polarized proton Collider Experiment
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 4
General Idea of Measurement
A
B
a
b
c
d
C
G Aa / D cC /
G Bb / D dD /
dt
dX
~3
3
dp
dE
)()(
)(
)(
)(~
/
/
/
/3
3
3
3
cdabaxG
xG
xG
xG
dpEd
dpEd
A LLbBb
bBb
aAa
aAa
UnPol. Case abcd
cC
abcd
bBbaAa zDdt
dxGxG )()()( ///
measurement
Structure Function pQCD Fragmentation Function
Asymmetry
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 5
Processes for Probes.
Gluon Compton
Charmonium
Open Heavy QuarkLight Flavor
High-Pt prompt
e+e-, +-
e+e-, +- ,e,e, ,,Jet(Charged Hadrons, pi0)
Ah
Bh
q
q
l
lW boson (Z,Drell-Yan) High-Pt , e,
e+e-, +-
signature
Processes
W
Many processes on P-P collision can be used.
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 6
Accelerator and
Detectors
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 7
Polarized Proton Collider : RHIC
AGS
LINACBOOSTER
Pol. Proton Source500 A, 300 s
1232max scm102 L
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
PHENIX
PHOBOSBRAHMS & PP2PP
STAR
onPolarizati Beam%70GeV50050 s
•Accelerator (ZELENSKI)
•Polarimeter (BRAVAR and JINNOUCHI)
•DetectorLocal Polarimeter Test set up
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 8
PHENIX collaboration
12 Countries 57 Institutions 460 Participants
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 9
PHENIXPioneering High Energy Nuclear Interaction eXperiment
PHENIX Detector1 Central Arm
e, g, Charged Hadrons detection |h|<0.35, Df=p
2, Muon Arm m detection 1.2<|h|<2.4, 2p in f
3, Forward detectors Luminosity Monitoring Local polarimetery
Good particle identification
High Rate and High Detector granularity.
Limited geometrical coverage
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 10
Coverage of Detector
0 1 2 3 4 5 Rapidity
STARFPD
PHENIX/STAR0o CAL
PHENIXBBC
PHE
NIX
MU
ON
PH
EN
IX C
EN
TR
AL
STA
R T
PC
pp2pp
XF 0.2 0.4 0.6 0.8PT
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 11
RHIC Run Summary at PHENIX
RUN Species EnergyLuminosi
tyPolarization
RUN 12000
Au + Au 130 GeV 1.0/mb
RUN 22001-2002
Au + Au 200 GeV 24/mb
P + P 200 GeV 150/nb Transverse
RUN 32002-2003
Au + Au 200 GeV 2.7/nb
P + P200 GeV 17/nb Transverse
200 GeV 350/nbLongitudina
l
Recorded on tape at PHENIX
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 12
pp-run-03 PHENIX integrated luminosity
352 nb-1 from 6.6x109 BBCLL1 triggers
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
800.00
900.00
1000.00
Date in proton run
Inte
grat
ed L
umin
osity
[nb
-1]
Integ. BBCLL1 Integ. ZDC
ZDC
BBC
STARrotators
pp2pp
Begin of Physics
2 IRsExtension: 180nb-1/wk, Pola-rization between 0.25 and 0.3.
Extended periods with pola-rization above 0.35 earlier inthe run.
Goal: 500nb-1/week at P=0.4
Commissioning: 5+3 weeks
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 13
Result from
RUN2 and RUN3
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 14
Central Arm Detector
)(GeV/ %0.1%7.0/ cppp
Tracking Detectors
2m ~ 4m from vertex
GeV)(
%2.8%9.1/
EEE
01.001.0~
Particle Identification
E.M. Calorimeter
High granularity
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 15
Leading hadrons as jet tags
ˆ
Hard Scattering Process
2P2 2x P
j 2f x
i 1f x1P
1 1x P
zhqD
s
1ps
2ps
gggg
G
G
G
G
gqgq
G
G
q
q
qqqq
q
q
q
q
qg+gq
gg
0
Fraction
's produced
Pt [GeV/c]
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 16
p reconstruction at RUN3
2-3 GeV/c Bckgr=17%
3-4 GeV/c Bckgr=7%
4-5 GeV/c Bckgr=5%
1-2 GeV/cBckgr=45%
Results obtained for four pt bins from 1 to 5 GeV/c
Pi0 peak width varies from 12 to 9.5 MeV/c2 from lowest to highest pt bins
Background contribution under pi0 peak for 25 MeV/c2 mass cut varies from 45% to 5% from lowest to highest pt bins
0
A. Bazilevsky will talk.
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 17
Gluon Polarization measurement by leading hadrons
Estimate with 30pb-1, 70% Pol. Simulation
for different charges for different G
h+
h-
A
B
C
0
h+
AL
L
AL
L
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 18
Physics of J/• Better understanding of Quantum Chromo-
dynamics (QCD) charmonium production includes perturbative QCD aspects non-perturbative QCD aspects
• (Un-polarized) p+p data are important as reference for heavy ion collision
In wide energy rangeCross sectionsPolarizationRelative yields (/ etc)
Resolve production mechanism
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 19
Muon Arms
Geometry Acceptance North : 1.2 <η< 2.4 South: -2.2<η<-1.2 Muon range cut off ~ 2GeV/c
m/prejection ~10^3
Muon Tracker (MuTr) Measurement of momentum
Muon Identifier (MuID) Muon identification Trigger Counter
North Muon Arm:2002~
South Muon Arm
2001~
North Muon Arm became operation in 2003 Run
Beam
μ
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 20
J/ Peaks at RUN2
• Clear J/ peaks with small background in both e+e- and +- pairs
NJ/=46 NJ/=65
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 21
J/ (s dependence)sm
xgxgx
dxs
c
J
/2
)/()()(1
/
• Energy dependence of J/ is sensitive to gluon distribution function and its scale Q
• Our new result and lower-energy results are consistent with typical gluon distribution functions with a reasonable choice of Q confirms the gluon fusion picture of J/ production in hadron-hadron collisions in a wide energy range
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 22
J/ (absolute value)
• Absolute normalization for J/ is sensitive to production model – Color-evaporation model (CEM)
can explain J/ using J/ (fraction of J/ to all produced cc pairs) ~ 0.06 determined by photo-production data
– Color-singlet model (CSM)
Color singlet production underestimate J/ by a large (~10) factor– Color-octet model (COM)
Consistent using the color octet matrix element <OJ/8(1S0)>+7/Mc
2< OJ/
8(3P0)> = 0.02 GeV3 from photo-production data, but has large uncertainties from
• Extraction of color-octet matrix element• Charm quark mass• Factorization and renormalization scales
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 23
J/ψ at RUN3
Invariant Mass (GeV)0 31 2 4 5 6
First Detection J/ψ with North Muon Arm
Data Sample: Dimuon TriggerIntegrated Luminosity: 143 nb (~50% of run3pp)Dimuon sample : 3MJ/ψ: ~ 227 J/ψ’s
Expected number of J/ψ: 600 (North and South) Almost 10 times Statistics -> Pt, and J/ψ polarization?
-1
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 24
XF
Physics of Forward DetectorsFNAL E704 and Qiu-Sterman model
Tra
nsve
rse
Sin
gle
Spi
n A
sym
met
ryA
N
FNAL E704 measured large transverse single spin asymmetry AN
Instead Zero expectation from lowest order pQCD calculation
Possible origins
Initial state interaction
Final state fragmentation
Higher twist effect
Can we use as “Polarimeter”?
Let’s measure at RHIC!
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 25
Neutron Asymmetry at RUN2
RL
RLNA
onPolarizati Beam
1
Transverse single spin Asymmetry
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 26
ZDC (Zero Degree Calorimeter) at PHENIX RUN3
beam beam
~ 1800cm
10cm
±2mrad
beam beam
-EM and Hadron Calorimeter -> neutron, •Sweep out all charged particles -> only neutron and •Tungsten, Scintillation fiber, 2 layer of tungsten•X-Y from fiber, energy deposit from tungsten •5.1λT 149X0 (3 ZDC)
DX magnet
5||3
ZDC ZDC
DX magnet
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 27
Measure change of Polarization VectorR
aw A
sy.
/ B
eam
Pol
.
f-p/2 0 p/2-p/2 0 p/2-p/2 0 p/2
Transeverse(Vert.) Transeverse(Horiz,) Longitudinal
Evaluate longitudinal component of beam by measuring transverse component of polarization.
p
pT
pL
2
1cos
pT
p
pL
p
<pL/p> Blue = 0.993
<pL/p> Yellow = 0.974
0.005 0.0000.014 0.0090.013 0.0010.032 0.009
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 28
PHENIX BBC
• 2 identical parts (BBC-north and -south)
• Quartz Cherenkov counter• 64 segments each.
NorthSouth
144.35 cm
⊿φ = 2π
9.3||0.3
29
Inclusive Charged Asymmetry in forward region (3<||<4)
• No finite AN was found with looking at charged particle.
• But Large AN was found in neutron.
• How about charged particle with neutron tag?
Neutron Tag
Forward Charged
Backward Charged
210)22.050.050.4( 210)10.055.028.2(
Forward AN =
Backward AN =PHENIX preliminary
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 30
What’ next?
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 31
Prompt photon production• Gluon Compton Dominates
– At LOLO no fragmentation function– Small contamination from annihilation
•
2i i 2
i u,d,s
2i i 2
i u,d,s
LL1
1LL
e f (xg(
)
e f (A
x )a (gq
x )
g(x )q )
A1
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 32
–clear interpretation• gluon Compton
process dominant
statistics with full design luminosity and polarization
prompt photon
GS95
x
G x
Gluon polarization measurement by Prompt photon
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 33
Physics from Open heavy flavors
Provides more independent DG measurements in PHENIXHelps control experimental and theoretical systematic errorsDifferent channels cover different kinematic regions
bbeX
direct
cceX
H. Sato
gg QQA BLL LL
A B
G(x ) G(x ) ˆA aG(x ) G(x )
Decay channels: e+e-, +-, e, e, , eD, D
X
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 34
ALL in PHENIX using -e coincidences
320pb-1 data will provide us a lot of e- coincidences event in PHENIX acceptance
230K from charm and 142K from bottom are expected.
At high Pt region, bottom begins to dominate
W. Xie & H. Sato
simulation
simulation
70% polarization
70% polarization
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 35
Physics from W production
Au x M d x M d x M u x M
u x M d x M d x M u x MLW a W b W a W b W
a W b W a W b W
( , ) ( , ) ( , ) ( , )
( , ) ( , ) ( , ) ( , )
2 2 2 2
2 2 2 2
• W Asymmetry
V-A + helicity conservation
),(
),(2
2
Wa
WaWL Mxu
MxuA
),(
),(2
2
Wa
WaWL Mxd
MxdA
when ba xx
ba xx when
ud
• W production1) Parity violation Good spin analyzer2) Weak charge Flavor decompositionu
d W
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 36
Flavor decomposition
W
Z
W dominates high Pt m (>20 GeV/c)pb 1-800Ldt GeV, 500 s
2003/09/17 SPIN03 Atsushi Taketani RIKEN/RBRC 37
In RUN3 PHENIX took longitudinally polarized proton-proton collision data with integrated luminosity 350/nb and average beam polarization 0.3. We measuredALL of inclusive 0
AN from forward detectors
PHENIX is well suited to the study of spin physics with a wide variety of probes.G with prompt , heavy flavor via lepton tagLeading particle from jet Anti-quark helicity distribution via W decay
Summary