Heavy Flavor and Charged Hadron Flow measurement using Silicon Vertex Detector at PHENIX
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Transcript of Heavy Flavor and Charged Hadron Flow measurement using Silicon Vertex Detector at PHENIX
Heavy Flavor and Charged Hadron Flow measurement using
Silicon Vertex Detector at PHENIX
Hiroshi Nakagomi for the SVX Groupand the PHENIX Collaboration
Univ. of Tsukuba/RIKEN2013/06/23
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Heavy Flavor(c,b) in Heavy Ion CollisionsMainly created at initial hard scatteringTraverse and interact with the hot and dense
medium.Good probe to study hot and dense medium
Previous PHENIX HF result
- RAA is suppressed ( c,b -> e) - Non zero v2 ( c,b -> e )
Surprising result
But the result is mixture of c and b -Separating c and b is needed
PRL 98 172301
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η dependence of v1,v2,v3
v1 as function of η:STAR0-40%
AuAu 200GeV
Phys.Rev.Lett. 101 252301
η3
η
Phys.Rev. C77 054901
AuAu200GeV10-40%
NN2012:STAR
AuAu200GeV
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v2,v3 as function of η:STAR - v2:Blue data point - v3:Red data point - |η|<1v2,v3 Flat distribution
Silicon Vertex Detector (VTX)
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Silicon Vertex detector was installed from run 2011 -Physics Motivation ・ Measurement of heavy flavor -Detector design ・ Barrel Type & 4 layers Inner 2 layers : pixel detector Outer 2 layers : strip detector ・ Δφ~2π ・ |η|<1.2
VTX:|η|<1.2
MPC:3.1<|η|<3.7
BBC:3.0<|η|<3.9
CNT:|η|<0.35
SMD/ZDC η
dN/dη
1.2-1.2 5-5
VTX Track Reconstruction
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VTX
DC+PCRICH
TOF EMCAL
Central Arm
DcTrack
B3B2B1B0
VTX
VTX Standalone Tracking - VTX can reconstruct charged particle tracks (require more than 3 hits on VTX) - Low momentum resolution - |η|<2.0 - Measurement Primary Vertex
Central Arms + VTX tracking - Central Arms track is associated with the VTX clusters(charged particle hits) - High momentum resolution - |η|<0.35 - Measurement DCA
There are two types of tracking
Separating c and b using DCA
Lifetime (ct) D0 : 125 mm B0 : 464 mm
DCA
AuAuD
B
e
e
Side View of VTX
We know the shape of each component from PYHIA simulation. By simultaneous fitting of DCA distribution, each component can be
separated statistically.
D and B mesons travel before semi-leptonic decay to electron
Measure DCA to separate c and b components of heavy flavor spectra. DCA corresponds to the life time.
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b->e/(c->e+b->e) in pp collision
Separate b->e , c->eConsistent with previous PHENIX result and FONLL calculation 7
v2 、v3 and Event Plane resolution
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pT/η dependence of v2, v3 - CNT- SVX track |η|<0.35 - standalone track |η|<1.5 η dependence of event plane resolution - Spectator vs Participant EP correlation - Participant vs Participant EP correlation
Analysis Method : Event Plane Method
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Event Plane(The angle a lot of the particles are emitted in)The angle the particles are emitted in
x
y
Event Plane with elliptic moment
10BBC South/North/South + North
centrality[%]/10
0
0.1
CNT+VTX tracks(CNT tracks was associated with stand-alone track of VTX) orVTX standalone tracks
Track reconstruction
Event Plane measurement
η
BBC
Nor
th
BBC
Sou
th
-1.2 1.2-3.9 -3.0 3.0 3.9
φ2π
0VT
X
CNT
0
0.1
0.2
Analysis Method : Event Plane Method
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• v2 and v3 of charged hadron has reduced background by application of
DCA cut < 200um.
• v2 are consistent with previous measurements of p0 v2 in high pT region.
PHENIX
v2,v3: pT dependence (CNT+VTX tracks)
PHENIX• Extend to high pT region for v3.
• Good agreement with previous data in low pT region.
• A non-zero v3 is still observed in high pT
region.
v2:pT dependence(VTX standalone tracks)
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Comparison with previous PHENIX result (PRL107.252301) v2
using CNT tracks and v2 using VTX standalone tracks - Standalone tracks pT region is 0.25<pt<1[GeV/c]
Au+Au √SNN= 200GeV
Consistent with previous PHENIX previous result pT<1[GeV/c]
v2: η dependence(standalone tracks)
Comparison to PHOBOS v2
- PHOBOS : centrality 25-60%, pt> 0[GeV/c] - PHENIX : centrality 20-60%, 0.25<pt< 1[GeV/c]
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Au+Au √SNN= 200GeV
Consistent with PHOBOS result within systematic errorbar
Event Plane Resolution: η dependenceSVX 0.5η slice EP resolution : 12 EP |η|<3
EP resolution reflects amplitudes of vn in sub-events and their Multiplicity
layer0layer1
layer2layer3
8 9 10 11 127654321
0-3 -2 -1 1 2 3ηBBC
SMDSMDBBC
SVX EP ResolutionRaw EP Correlation
SMD/BBC EP Resolution
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EP Resolution :
Similar to v1 distributionDepend on SMD Plane: SMD S> SMD SN > SMD N
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Strong centrality dependenceAt η=0, Multiplicity is high. Triangular shapeNo EP selection dependence
EP Resolution :
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At Mid-rapidity , data points are minus value , - Momentum ConservationThe data points become plus value at the rapidity EP is
measured , - Non flow effect
EP Resolution :
η>0
η<0
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Similar to Psi2 Correlation using SMDThe data points become lager at the rapidity
EP is measured - Non flow Effect
EP Resolution :
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Similar to Psi2 Correlation – Symmetry distribution Weak Centrality dependence like v3
EP Resolution :
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Summary
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Heavy Flavor Separate c and b in pp collision
Event Plane resolution (SVX 0.5 slice) Psi1 vs Psi1 - Spectator vs Participant : similar to v1 、 Depend on SMD( SMD S > SMD SN > SMD N) - Participant vs Participant : momentum conservation , non flow Psi1 vs Psi2 - Spectator vs Participant : similar to v2 Psi2 vs Psi2 - Similar to Psi2 resolution using SMD, non flow Psi3 vs Psi3 - Similar to Psi2 resolution distribution
Charged Hadron v2 ,v3
pT dependence|η|<0.35 : Consistent with previous result pT dependence |η|<1.5 : Consistent with previous result below 1 [GeV/c] η dependence : Consistent with PHOBOS result
v2 :
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VTX 0.5-η slice
VTX cluster(charged particle hit)
Z
0
layer0
layer1
layer2
layer3Used clusters were in these region
was measured in this region(Δη=0.5)
BBC South BBC North
Δη=0.5
centrality[%]0 10050
Au+Au √SNN= 200GeV
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VTX 0.5-η slice
VTX cluster(charged particle hit)
centrality[%]0 10050
I divided VTX into 12 parts by 0.5η slice.
0-3.0 -2.0 -1.0 1.0 2.0 3.0layer0
layer1layer2
layer3
η
η coordinate
Au+Au √SNN= 200GeV
v2 :
layer0layer1
layer2layer3
8 9 10 11 127654321
0-3.0 -2.0 -1.0 1.0 2.0 3.0 ηI calculated correlation between BBC NS and these region. 23
VTX 0.5-η slice
VTX cluster(charged particle hit)
centrality[%]0 10050
Au+Au √SNN= 200GeV
v2 :
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VTX 0.5-η slice
VTX cluster(charged particle hit)
centrality[%]0 10050
0
centrality[%] 0
0.05
0.1
0.15-3.0 -2.0 -1.0 1.0 2.0 3.0
η
Au+Au √SNN= 200GeV
v2 :
v2:
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η dependence of v2 using cluster(charged particle hit) - no BG subtraction and no pt selection v2 around EP measurement region is higher than v2 in other region - Non flow effect is seen - Non flow effect seems to be asymmetry. We should separate Mid-rapidity side : Δη=1.5 , Forward rapidity side : Δη=1
η
EP measurement region(0.5<η<1)
Au+Au √SNN= 200GeVperformance plot
η
v2:
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0<|η|<0.5 0.5<|η|<1 1<|η|<1.5 1.5<|η|<2
Au+Au √SNN= 200GeV
v 2 using EP measured in other rapidity region( Black:η<0, Red:η>0) In other EP measurement regions, v2 distributions also look asymmetry.
performance plot
EP Resolution : BBC Psi2, Psi3
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EP Resolution : SMD Psi1, Psi2
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dN/dη