Download - Spin Physics at RHIC-PHENIX
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Oct. 11,12, 2006 K.Okada 1
Spin Physics at RHIC-PHENIX
K.Okada
Riken BNL research center
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Oct. 11,12, 2006 K.Okada 2
Contents— One of physics fields … Structure of nucleons— RHIC accelerator— PHENIX detector— Analysis— Result— Outlook— Summary
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Oct. 11,12, 2006 K.Okada 3
Structure of nucleonsWhat is inside the proton?
Mainly from DIS measurementlepton
nucleon
f(x,2): depends on the energy scale, the evolution is known
Q2
[GeV
2 ]
x
xf(x
)
x
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Oct. 11,12, 2006 K.Okada 4
Structure of nucleons (Polarized)
nucleon target
*
or
or
quark
lepton beam
Polarized lepton, polarized nucleon
),(),(),( 222 xqxqxq
x
x△u(x)
x△d(x)
x△u(x)
x△d(x)
x△s(x)Semi-inclusive DIS
Where is gluon?
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Oct. 11,12, 2006 K.Okada 5
Gluon polarization?
~0.25, g, L unknown
Origin of the nucleon spin 1/2 ?
quark gluonAngular momentum
Poor information from polarized DIS experiment
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Oct. 11,12, 2006 K.Okada 6
Gluon polarization?
g2 gq q2
Hard Scattering Process
2P2 2x P
1P
1 1x P
How to measure g:0
0
LLA
Polarized hadronic collisions
Any interaction related to gluon can be a probe(0 , Jet, h±, Direct , J/psi, charm…)
++: cross section in +-: in
Gluon interaction in the first order.High energy to apply the perturbative QCD.
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Oct. 11,12, 2006 K.Okada 7
Relativistic Heavy Ion Collider
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Oct. 11,12, 2006 K.Okada 8
Relativistic Heavy Ion Collider
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RHIC
Ion source
Proton source
PHENIXexperiment
• Relativistic Heavey Ion Collider (for QGP) • and the first collider of polarized proton
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Oct. 11,12, 2006 K.Okada 10
Key features of RHIC
+-+-+---++--++
Keep the polarization during the acceleration. Several techniques (Siberian snake etc.)
Different helicity configuration in every 106ns. (Cancellation of the detector effect in the asymmetry)
Polarimetry (Hiromi’s ph.D thesis)
LLA
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Oct. 11,12, 2006 K.Okada 11
H-jet measures beam polarization at RHIC
Vol 45, number 8
638 (2006) 450
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Oct. 11,12, 2006 K.Okada 12
PHENIX detector
proton proton
Central arms+ Forward muon arms
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Oct. 11,12, 2006 K.Okada 13
PHENIX central arm trigger—Requirement:
5kHz (Data acquisition limit) Rejection power ~100
—EMCal and RICH trigger
12301020)6( scmrunL
vertex cut (~0.5)Collision trigger (~0.5)
(s=200GeV)
~200kHz collision rate
2006
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Oct. 11,12, 2006 K.Okada 14
Concept of EMCal-RICH trigger
h
(0)PHENIX central arm2 types of EMCal (PbSc, PbGl)
EMCalRICH
EMCal RICH
(0) : EMCalElectron : EMCal and RICHHigh energy hadron : EMCal (through hadronic interactions) and RICH
(Ring Image Cherenkov detector)
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Oct. 11,12, 2006 K.Okada 15
EMCal turn-on curve is important
Because of the steep falling distribution of the maximum energy in a event,The rejection power is determined by the lower tail.
E[GeV]
Important for RP!
PMT gain variation + Trigger tile variation
I established a procedure to reduce these variations.Now two terms are comparable.
Distribution of the highest cluster energy in a event from run3 pp data.
E[GeV]
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Rejection Power Improvements
Rejection power of 4x4 triggers improved for more than 2 times.
Old RP New RP
The threshold resolution improvement resulted in the rejection power (RP) increase.
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Oct. 11,12, 2006 K.Okada 17
PHENIX polarized-proton runs
Year s [GeV] Recorded L Pol [%] FOM (P4L)
2003 (Run 3) 200 .35 pb-1 27 1.5 nb-1
2004 (Run 4) 200 .12 pb-1 40 3.3 nb-1
2005 (Run 5) 200 3.4 pb-1 46 150 nb-1
2006 (Run 6) 200 7.5 pb-1 62 1100 nb-1
2006 (Run 6) 62.4 .08 pb-1 ** 48 4.2 nb-1 **
Longitudinally Polarized Runs
Transversely Polarized Runs
Year s [GeV] Recorded L Pol [%] FOM (P2L)
2001 (Run 2) 200 .15 pb-1 15 3.4 nb-1
2005 (Run 5) 200 .16 pb-1 47 38 nb-1
2006 (Run 6) 200 2.7 pb-1 57 880 nb-1
2006 (Run 6) 62.4 .02 pb-1 ** 48 4.6 nb-1 **
** Not yet finalized
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Oct. 11,12, 2006 K.Okada 18
Analysis (briefly)
1<p<2GeV 3<p<4GeV 8<p<9GeV
EMCal Calibration MIP electron E/p Mgg pi0 peak position
Invariant mass of 2 photons
At first, we need to confirm the theory baseline Cross section measurement
Example : 0
Luminosity Beam current, size Trigger rate
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Oct. 11,12, 2006 K.Okada 19
T
0 cross section at 200GeV
NLO pQCD calculations are consistent with cross-section measurements
g2 gq q2
2P2 2x P
1P
1 1x P
Run2: PRL91,241803(2003)
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Oct. 11,12, 2006 K.Okada 20
ALL of 0 at s=200GeV
• 0 ALL vs. pT from Run6 Filtered data compared with Run5 Preliminary photon triggered data as well as Run5 Minimum bias below 1 GeV
Run-6 Data set from 2.0-2.7 times improvement on statistical uncertainties from Run5.Lower pT Run-6 points will come with full production
0
LLA
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Oct. 11,12, 2006 K.Okada 21
ALL of 0 at s=200GeV
» Run5 data not consistent GRSV-max in this x-range.» Run6 sufficient to differentiate GRV-std from g=0
g = 0.42at Q2=1(GeV/c)2
best fit to DIS data
g = 1.84
Run-6 Data set from 2.0-2.7 times improvement on statistical uncertainties from Run5.Lower pT Run-6 points will come with full production
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Oct. 11,12, 2006 K.Okada 22
Determination of gA global analysys (PHENIX+ other experimental data)
For example hep-ph/0603213 (Hirai et. al)
Type 2 : JLab, HERMES, COMPASS
Type 1: Type 2+ PHENIX 0
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Oct. 11,12, 2006 K.Okada 23
Gluon Compton Dominates– At LOLO no fragmentation function– Small contamination from
annihilation
1g
gL LT
pqL L
g(x )
g(xA (x ) a
)A (p )
hep-ex/
0609031
Prompt production at s=200GeV
Run 32P 2 2x P
1P
1 1x P
qqgq
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Oct. 11,12, 2006 K.Okada 24
Yie
ld (
Arb
itrar
y un
it)
pT[GeV/c]
Other reactions (central arm)Reminder: any reaction contains gluon brings the information.
0 until merging in high pT
± low trigger eff. Clean but needs luminosity
0
NPALL
112
PN
:Beam polarization:Yield
In PHENIX
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Other observables related to spin— ALL (difference of + and + ) gluon polarization etc.
0, ±,Direct ,Jet, J/psi, open charm Jet correlation
— AN (left-right asymmetry in +• )Asymmetry in forward region (E704, STAR, BRAHMS)
At PHENIX Asymmetry in Very forward neutron Zero in 0,h±production in the central region.
Both experiment and theory are developing.It might be interesting.
— AL ( Difference of +• and +• )Parity violating mode (=weak interaction)Difference between flavorsNeed high luminosity for W production.
— Spin transfer (correlation between beam state and final state ) etc. — ATT (difference of + and + )
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Oct. 11,12, 2006 K.Okada 26
Outlook
Charm, Beauty With silicon VTX
Spin Plan ReportBNL-73798-2005
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Oct. 11,12, 2006 K.Okada 27
Detector upgrade (PHENIX-SPIN)
— Forward calorimeters (MPC, nose-cone)
Transverse spin physicsKinematics
— Silicon VTX detectorCharm, Beauty detectionKinematics
W physics
—Forward muon trigger upgrade
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Summary
— ALL ( difference between + and +) : gluon spinResults of 0 (the highest statistics) (The gluon polarization is low.)
— AN ( left-right asymmetry in +• )
• RHIC-PHENIX status
• Future
The asymmetry is observed at RHIC energy in the forward region.Relatively new field in both theory and experiment.
Settle the issue of gluon polarizationPossibility of AN physicsFlavor separation with W production