Transcript ppt - 東京工業大学

Measurements of J/ψ
with PHENIX Muon Arms
in 2003 p+p Collisions
東京工業大学 理工学研究科
神原 信幸
for the PHENIX Collaboration
日本物理学会 2003年 秋季大会
2003年9月11日
Content
1. Physics motivation
2. PHENIX Muon Arms
3. Detector Performance
4. J/ψ Mass
5. J/ψ Polarization
6. Summary
2003年9月11日
日本物理学会秋季大会
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Physics Motivation
Spin Structure of Proton
J /
J /
(   )  (   )
J /
J /
(   )  (   )
 A
J/ 
LL

 g ( x1 )

g ( x1 )
g ( x2 )
g ( x2 )
g  g  J /
 a LL
There is theoretical ambiguity for J/ψ
production mechanism
Cross section for J/ψ production, J/ψ Polarization
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J/ψ Polarization
There are three J/ψ production models.
Color Singlet Model (CSM)
λ> 0 Transverse
Color Evaporation Model ( CEM) λ= 0 Unpolarized
Color Octet Model (COM)
λ < 0 Longitudinal
d


dcos 


~ 1   cos 
2


+
θ* is the angle between the μ in
the J/ψ
rest frame and J/ψmomentum direction.
J/ψ Momentum direction
J/ψ polarization can distinguish these models
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PHENIX Muon Arms
North Muon Arm became operation in 2003 Run
μ
Muon Tracker (MuTr)
Measurement of momentum
Muon Identifier (MuID)
Beam
South Muon Arm
2001~
s  200 GeV
North Muon Arm:
2002~
Proton-Proton Collision
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Muon identification
Trigger Counter
Geometry Acceptance
North : 1.2 <η< 2.4
South: -2.2<η<-1.2
Muon range cut off ~ 2GeV/c
Longitudinal Polarization
average 27%
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Muon Trigger by MuID
MuID is divided by 4(“Quadrant”)
z direction
Coincidences in z direction
at each Quadrant make muon
road for trigger signal.
Quadrant
Horizontal
Quadrant
Look Up
Table
Muon Trigger signal
• single muon
•dimuon
Quadrant
Vertical
2003年9月11日
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Hit Information
from MuID
Trigger
electronics
Efficiency
Trigger Circuit Efficiency
Trig
Signal
1
0.95
0.8
0.6
0.4
Trigger
Emulator
Recorded by DAQ
Trigger
Circuit
0.2
Trigger 0
Emulation
Efficiency

88000
90000 92000
Run Number
# (Trig Signal  Trigger
using Minimum Bias events
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# Trigger
日本物理学会秋季大会
Emulation)
Emulation
7
1
D.F
D.F
MuID HV Status
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
88000 90000 92000
South MuID
Duty Fraction

88000 90000 92000
Run Number
Run Number
North MuID
 ( # of live HV channel)
 (# of HV channel)
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dt
dt
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Select more than
30 minutes Run
8
J/ψ Mass
First Detection J/ψ with North Muon Arm
0
1
2
3 4
5 6
Invariant Mass (GeV)
Data Sample: Dimuon Trigger
Integrated Luminosity: 143 nb-1 (~50% of run3pp (350 nb -1 ) )
Dimuon sample : 3M
J/ψ: ~ 227 J/ψ’s
Expected number of J/ψ: 600 (North and South)
2003年9月11日
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Yield (Arbitrary unit)
How can we determine J/ψ
Polarization?
λ = 1 Transverse
λ = 0 Unpolarized
λ = -1 Longitudinal
Pt(J/ψ) > 2 GeV/c
Using Pt(J/ψ) distribution by Run2
GRV94
d
0
0.2
0.4
0.6
0.8

| cos  |
1
dcos 
~ 1   cos 
2


J/ψ number for evaluating error: 200 (Pt(J/ψ)>2Gev/c)
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日本物理学会秋季大会
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Summary





PHENIX took polarized proton-proton collision
-1
nb
data at √s = 200 GeV with 350
integrated
luminosity in 2003 Run.
North Muon Arm was newly installed in 2003 Run.
Muon Trigger at both Arms were working well.
J/ψ was measured with both Muon Arms.
We confirm J/ψ Polarization is measurable.
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J/ψ Mass
0
1
2
South Arm
3 4
5 6
Invariant Mass (GeV)
Data Sample: Dimuon sample
Integrated Luminosity: 143 nb-1 (65% of run3pp)
Dimuon sample : 1M
J/ψ: ~ 98 J/ψ’s
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日本物理学会秋季大会
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