Prompt identified particle spectra at RHIC-STAR...Prompt identified particle spectra at RHIC-STAR...
Transcript of Prompt identified particle spectra at RHIC-STAR...Prompt identified particle spectra at RHIC-STAR...
Prompt identified particle spectra at RHIC-STAR
Sanshiro Mizuno for the STAR collaboration
University of [email protected]
Sanshiro Mizuno, CiRfSE workshop
Motivation• Inclusive proton includes ~40% of protons from weak decay in Au+Au 200GeV.
• STAR - inclusive proton spectra not corrected for weak decay feed down contributionPHENIX - prompt proton spectra proton coming from Λ is estimated based on model simulations
• This result will be first direct measurement of prompt proton pT spectra with new HFT detector at RHIC. - Uncertainty will decrease significantly due to smaller simulation correction.
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PRL 92, 112301 (2004)PRC 69, 034909 (2004)
Sanshiro Mizuno, CiRfSE workshop
STAR detector
Vertex Position DetectorMinimum bias trigger Time Projection Chamber Centrality definition Particle trajectoryMomentum PID (dE/dx)Time Of FlightPID (flight time : 1/β) Heavy Flavor Tracker
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TOF
TPC
VPD
HFT
Sanshiro Mizuno, CiRfSE workshop
Heavy Flavor Tracker detector
Silicon Strip Detector : r~22cm Intermediate Silicon Tracker : r~14cm
PIXEL : r~2.8, 8cm
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PIXEL detectorAcceptance -1 < η < 1 0 < φ < 2πGood resolution of DCA(Distance of Closest Approach)Particle track - collision point
Sanshiro Mizuno, CiRfSE workshop
(cm)XYDCA0.05− 0 0.050
20000
40000
60000
80000 Au+Au 200GeV0-10%
distributionXYDCA<0.3GeV/c
T0.2<p
mµWidth=115
(cm)ZDCA0.05− 0 0.050
20000
40000
60000
80000 distributionZDCA<0.3GeV/c
T0.2<p
mµWidth=123
(cm)XYDCA0.05− 0 0.050
50
100
310×
DCA distributionGaussian fit
distributionXYDCA<1.1GeV/c
T1.0<p
mµWidth=27.9
(cm)ZDCA0.05− 0 0.050
20000400006000080000
distributionZDCA<1.1GeV/c
T1.0<p
mµWidth=31.1
HFT performance
DCA in XY plane and Z directionWidth : <50μm at pT=1GeV/c
DCA Resolution
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DCA distribution from data in AuAu 200GeV
0-10% centrality
inclusive charged particles
Run14 Au+Au @200GeV
Sanshiro Mizuno, CiRfSE workshop
(k)β-1/β1/0.05− 0 0.05 0.1
Cou
nt500
1000
1500
2000 Au+Au 200GeV, 0-10%<1.7 (GeV/c)
T1.6<p|y|<0.1
|<2Kσ|nmµ<40.4XYDCA
mµ<45.8ZDCA
Kσn5− 0 5
Cou
nt
1
10
210
310
410
510
610
Combined fitpionkaonproton
Au+Au 200GeV, 0-10%<0.6 (GeV/c)
T0.5<p|y|<0.1
mµ<99.2XYDCAmµ<109.6ZDCA
Particle IdentificationTrack selectionAt least one hit for each HFT layerDCA selection is determined with resolution.
dE/dx in TPC dE/dx in TPC and β in TOF
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Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3 4
MC
-pro
mpt
/ N
RC
-pro
mpt
= N
acc.
×ef
f.ε
0
0.2
0.4
0.6 +πAu+Au 200GeV0-10%
(GeV/c)T
p0 1 2 3 4
MC
-pro
mpt
/ N
RC
-pro
mpt
= N
acc.
×ef
f.ε
0
0.2
0.4
0.6 +Kthreshold :
=3)/2T
(pacc.×eff.ε
(GeV/c)T
p0 1 2 3 4
MC
-pro
mpt
/ N
RC
-pro
mpt
= N
acc.
×ef
f.ε
0
0.2
0.4
0.6
acc.×eff.εthreshold<<thresholdacc.×eff.ε
proton
Detector inefficiency & acceptanceExtracted from HIJING and GEANT simulation The combination of TPC and HFT efficiency and acceptance
NMC-prompt particle : The number of created prompt particles NRC-prompt particle : The number of reconstructed real prompt particles
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"e↵.⇥acc. =
NRC�prompt particle
NMC�prompt particle
F = A exp
(�✓
a
pT
◆b)
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 0.5 1 1.5 2
RC
-all
/ N
RC
-pro
mpt
= N
purit
yε
0.8
0.85
0.9
0.95
1
protonAu+Au 200GeV0-10%
=3)/2T
(pacc.×eff.εthreshold :
weak decay + knockout background>1GeV/c
T <1% at p
(GeV/c)T
p0 0.5 1 1.5 2
RC
-all
/ N
RC
-pro
mpt
= N
purit
yε
0.8
0.85
0.9
0.95
1
anti-protonacc.×eff.εthreshold<
<thresholdacc.×eff.ε
acc.×eff.εthreshold<<thresholdacc.×eff.ε
weak decay contribution>1GeV/c
T <1% at p
The purity of prompt particlesExtracted from HIJING and GEANT simulation.NRC-all particle : The number of reconstructed all of particles NRC-prompt particle : The number of reconstructed real prompt particles
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"purity
=N
RC�prompt particle
NRC�all particle
F = A exp
(�✓
a
pT
◆b)
Sanshiro Mizuno, CiRfSE workshop
pT spectra correction
Systematic uncertainty TPC efficiency : ~5% HFT matching efficiency : <13% The difference of HFT matching efficiency between data and simulationDCA selection : <10% Particle species dependent
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1
2⇡pT
d2N
dpT dy=
1
2⇡pT
1
Nevt
"purity"e↵.⇥acc.
N
�pT�y
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
2−10
1−10
1
10
210
positive+π+K
proton
Au+Au 200GeV, 0-10%STAR preliminary
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
2−10
1−10
1
10
210
negative-π-K
anti-proton
π, K, p pT spectra
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PID spectra with the HFT in Au-Au 200GeV The shape depends on particle mass.
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310
STAR preliminaryFit to STAR preliminary
STAR (2004)PHENIX (2004)
Au+Au 200GeV, 0-10%+π
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310
STAR (2006)
+K
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310Inclusive protonInclusive protonPrompt proton
proton
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 +π
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 +K
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 proton
π, K, p pT spectra
Modify Hagedorn equationSTAR results (orange, cyan) : inclusive proton PHENIX results (magenta) : corrected for weak decay from Λ 10
PRL 92, 112301 (2004)PRC 69, 034909 (2004)PRL 97, 152301 (2006)F =
A
{exp (�apT � bp2T ) + pT /p0}n
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310
STAR preliminaryFit to STAR preliminary
STAR (2004)PHENIX (2004)
Au+Au 200GeV, 0-10%-π
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310
STAR (2006)
-K
(GeV/c)T
p0 1 2 3
dy)
TN
/(dp
2)d Tp
π1/
(2
3−10
2−10
1−10
1
10
210
310Inclusive protonInclusive protonPrompt proton
anti-proton
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 -π
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 -K
(GeV/c)T
p0 1 2 3
Dat
a/Fi
t
0.5
1
1.5
2 anti-proton
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PRL 92, 112301 (2004)PRC 69, 034909 (2004)PRL 97, 152301 (2006)
π, K, p pT spectra
Modify Hagedorn equationSTAR results (orange, cyan) : inclusive proton PHENIX results (magenta) : corrected for weak decay from Λ
F =
A
{exp (�apT � bp2T ) + pT /p0}n
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3
Rat
io
0.4
0.6
0.8
1
1.2
STAR preliminary
+π/-πAu+Au 200GeV, 0-10%
(GeV/c)T
p0 1 2 3
Rat
io0.4
0.6
0.8
1
1.2+/K-K
(GeV/c)T
p0 1 2 3
Rat
io
0.4
0.6
0.8
1
1.2/pp
Anti-particle to particle ratio
The ratios are about 1, 0.95, 0.8 for π, K, p at RHIC energy.
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Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3
Rat
io
0.4
0.6
0.8
1
1.2
STAR preliminarySTAR (2004)PHENIX (2004)STAR (2006)
+π/-πAu+Au 200GeV, 0-10%
(GeV/c)T
p0 1 2 3
Rat
io0.4
0.6
0.8
1
1.2+/K-K
(GeV/c)T
p0 1 2 3
Rat
io
0.4
0.6
0.8
1
1.2
Inclusive protonInclusive protonPrompt proton
/pp
Anti-particle to particle ratio
There is no significant difference between inclusive and prompt proton ratio.
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PRL 92, 112301 (2004)PRC 69, 034909 (2004)PRL 97, 152301 (2006)
Sanshiro Mizuno, CiRfSE workshop
)2(GeV/c0 - mTm0 0.5 1 1.5 2
dy)
TN
/(dm
2 d
0
10
20
T0-mTm
- expTF = A m
proton Au+Au 200GeV0-10%|y|<0.1
Estimating dN/dy distribution
For pion, Bose-Einstein equation, mT exponential (for estimating systematics)For kaon and proton, pT exponential, mT exponential
measured dN/dy extrapolated dN/dylow pT
extrapolated dN/dyhigh pT
π+ 168.7 (53.5%) 146.7 (46.4%) 0.14 (0.1%)
K+ 26.8 (50%) 26.7 (49%) 0.1 (1%)
proton 11.1 (51%) 10.4(48%) 0.11 (1%)
Fraction of dN/dy
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Out of range of measured spectraExtrapolating with equations The difference of equations are defined as systematic uncertainty.
Sanshiro Mizuno, CiRfSE workshop
partN0 100 200 300
dN/d
y
0
100
200
300 STAR preliminarySTAR (2004)PHENIX (2004)
+π
partN0 100 200 300
dN/d
y
0
20
40
60
+K
partN0 100 200 300
dN/d
y
0
10
20
30
40Inclusive protonPrompt proton
proton
partN0 100 200 300
dN/d
y
0
100
200
300-π
Au+Au 200GeV|y|<0.1
partN0 100 200 300
dN/d
y
0
20
40
60
-K
partN0 100 200 300
dN/d
y
0
10
20
30
40 anti-proton
dN/dy distribution
15PRL 92, 112301 (2004)PRC 69, 034909 (2004)
STAR results (orange, cyan) : inclusive proton PHENIX results (magenta) : corrected for weak decay from Λ
Sanshiro Mizuno, CiRfSE workshop
Summary
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• The first result of prompt π, K, p pT spectra with the HFT in Au+Au 200GeV collisions at STAR experiment
• The anti-particle to particle ratio There is no significant difference between inclusive and prompt proton results.
• Prompt particle azimuthal anisotropy Important for kinetic freeze-out parameters
Sanshiro Mizuno, CiRfSE workshop
Sanshiro Mizuno, CiRfSE workshop
(GeV/c)T
p0 1 2 3 4
acc.
×ef
f.ε
1/
0
10
20
30
40 +πAu+Au 200GeV0-10%
(GeV/c)T
p0 1 2 3 4
acc.
×ef
f.ε
1/
0
10
20
30
40 +Kthreshold :
=3)/2T
(pacc.×eff.ε
acc.×eff.εthreshold<<thresholdacc.×eff.ε
(GeV/c)T
p0 1 2 3 4
acc.
×ef
f.ε
1/
0
10
20
30
40proton
Efficiency correction
"e↵.⇥acc. =
NRC�prompt particle
NMC�prompt particle
Correction of detector efficiency and acceptance Correction factor get large in low pT region