Transcript p0 v2 Analysis in sNN = 200GeV Au+Au collisions

v2 study
in sNN = 200GeV
Au+Au collisions
0
p
KANETA, Masashi
for the PHENIX Collaboration
RIKEN-BNL Research Center
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Why Event Anisotropy?
• Because of sensitive to collision geometry
– In low pT (~<2 GeV/c)
• Pressure gradient of early stage
• Hydrodynamical picture is established
– In high pT (>~2 GeV/c)
• Energy loss in dense medium (Jet Quenching)
• Partonic flow(?)
Here we focus on
ellipticity of azimuthal
momentum distribution, v2
(second Fourier coefficient)
y
z
x
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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PHENIX Experiment
• Lead Scintillator and Lead Glass
EMCs
– Gamma measurement (p0gg)
• BBCs and ZDCs
– Collision centrality determination
• BBCs
– Reaction plane determination and
– Its resolution correction
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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BBC in PHENIX
• inner ring
• middle ring
• outer ring
BBC
64 elements
Quartz Cherenkov radiator
meshed
dynode
PMT
South
North
⊿η = 3.1 ~ 4.0
144.35 cm
Masashi Kaneta, RBRC, BNL
⊿φ = 2π
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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PbGl and PbSc EMC’s
•
•
•
•
•2
Sectors PbGl
•1
PbGl Sector
•
•1
•1
1 PbSc tower:
• 66 sampling cells
• 1.5 mm Pb, 4 mm Sc
• Ganged together by penetrating wavelength
shifting fibers for light collection
• Readout: FEU115M phototubes
16x12 supermodules (SM)
PbGl SM
•
•
1 Sector = 6x3 Supermodules (SM)
1 PbSc SM = 12x12 towers
PbSc towers: 5.52 x 5.52 x 33 cm3 (18 X0)
15552 blocks total
6x4 towers
Separate reference system
FEM
•
Reads out 2x3 supermodules or 12x12 towers
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Method of p0 v2 Measurement
• Define reaction plane by charged multiplicity on
Beam-Beam Counters
• p0 reconstruction from gamma measured by
Electro-Magnetic Calorimeter (EMC)
• For each pT, azimuthal angle, centrality
• Combine both information
– Counting number of p0 as a function of

dN 3
1
d 2N 

measured
E 3 
cos[n  r ]
1   2 vn
d p 2p pT dpT dy  n1
 where n  1,2,3,....
event anisotropy parameter measured
reaction plane angle
azimuthal angle of the particle
vnreal = vnmeasured/ (reaction plane resolution)n
Note: the detail of reaction plane definition will be found in nucl-ex/0305013
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Reaction Plane Defined by BBC’s
• BBC north and south
(h~3-4) are used
• Resolution calculation
Correlation of two BBC’s
- p /2
p/2
– Two sub-events are selected
– North and south
- p /2
Masashi Kaneta, RBRC, BNL
p/2
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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p0 Identification
• Requirement for photon
–
–
–
–
–
Dead and noisy EMC towers are removed for the analysis
Energy of shower on EMC>0.040 [GeV]
PID cuts: c2<3 for photon probability
|TOF|<1.2 [ns]
Note: those cut are loser than single pT distribution analysis
• For p0
– Asymmetry cut: |E1–E2| / ( E1+E2) < 0.8
– Combinatorial background is estimated by event mixing
• Classes categorized for event mixing
– centrality : every 10%
– BBC Z Vertex : every 10cm in ±30cm
– reaction plane direction in PHENIX detector : 24 bins in ±p
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Example Plots from the Analysis Procedure
Invariant mass of gg from same event and mixed event (classed by reaction plane, centrality, vertex position)
200GeV Au+Au
After subtraction, there is 2nd component
of B.G. in pT<2GeV/c region
normalization range
for combinatorial B.G.
subtraction
shape assumed as
linear+asym. Gauss
mgg [GeV/c2]
mgg [GeV/c2]
count number of p0 in a range
after 2nd B.G. subtraction
(not used the fit function)
FR [rad]
Masashi Kaneta, RBRC, BNL
Fit function:
(average of p0 count)  ( 1 + 2 v2 cos[2( - FR)])
Green lines : deviation by error of v2
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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One of difficulties (?) is..
• The analysis of p0 v2
– Counting number of p0 as a function of
centrality, pT and -FR
– The analyses (fitting of combinatorial background, its
subtraction, counting p0 and so on) are done by
macro automatically
– However, we need to think it is not perfect,
that is, it may fail sometime
• Therefore, ....
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Toooooooooo many histograms checked by eyes
Example of invariant mass distributions for each pT, -FR in a centrality bin
Before combinatorial background subtraction
Masashi Kaneta, RBRC, BNL
After combinatorial background subtraction
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
p0 as a function
of FRb
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v2 vs. pT vs. Centrality from 200GeV Au+Au
Statistical error is shown by error bar
Systematic error from p0 count method and reaction plane determination is shown by gray box
phenix preliminary
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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v2 vs. pT vs. Centrality from 200GeV Au+Au
Statistical error is shown by error bar
Systematic error from p0 count method and reaction plane determination is shown by gray box
The charged p and K v2 are shown only with statistical errors
phenix preliminary
}nucl-ex/0305013
• Charged p+K v2 consistent with p0 v2 in pT<4GeV/c
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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v2 vs. pT (Minimum Bias) from 200GeV Au+Au
• Identified particle v2 up to pT=10GeV/c
phenix preliminary
36.3106 [events] = 5.3+0.5-0.4 [(mb)-1]
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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v2 vs. pT (Minimum Bias) from 200GeV Au+Au
• Identified particle v2 up to pT=10GeV/c
phenix preliminary
}nucl-ex/0305013
36.3106 [events] = 5.3+0.5-0.4 [(mb)-1]
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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v2 vs. pT (Minimum Bias) from 200GeV Au+Au
• Identified particle v2 up to pT=10GeV/c
phenix preliminary
nucl-ex/0305013
36.3106 [events] = 5.3+0.5-0.4 [(mb)-1]
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Comparison with K0S and L (STAR)
STAR data from
nucl-ex/0306008
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Quark Coalescence?
• Phys. Rev. Lett. 91 (2003) 092301, D.Molnar and S.A. Voloshin
--• qqmeson,
qqq(qqq)Baryon
• How data looks like?
• Non-strange and
strange meson and
baryon seems to be
merged around
pT/nquark 1-3GeV/c
• But we need more
statistics to
conclude it
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Comparison with a model
Hydrodynamical calculation
phenix preliminary
Hydrodynamical calculation agreed in pT~<2 GeV/c. After that, it is deviated.
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
19
Comparison with a model
phenix preliminary
Special thanks to
C. Nonaka (one of authors)
of nucl-th/0306027 for
data of model calculation
Comparison with a model which is described in nucl-th/0306027. Here we don't
want to discuss which model can describe the data. To conclude which model
can describe the data, we need much more statistics in high pT region.
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Summary
• First measurement of p0 v2 at RHIC
– In pT=1-10 GeV/c
– v2 of the highest pT from identified particle
• Charged p v2 consistent with p0 v2
– In pT=1-3GeV/c
• Minimum bias data shows finite p0 v2
– Up to pT~8 GeV/c
Special thanks to LBL and STAR people, especially
Art Poskanzer
– I learned all of event anisotropy analysis when I was here
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Outlook
• Feature plan of analysis
– Using high pT gamma trigger in run2 Au+Au data
• We will have about twice statistics in high pT
• need to study trigger bias
– therefore, present analysis results are from minimum bias trigger
events
– h v2 is also available by same method
– PHENIX has photon v2 also (STAR also, but not opened yet)
– photon v2, especially low pT!
• RHIC run4 Au+Au, it will be
– Much more statistics
• Detail study of v2 shape around pT=2-4GeV/c
– Much higher pT
• We want to know where is the end of finite v2 in very high pT
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Future Plan of Event Anisotropy Analysis in PHENIX
• Trying v2 for all of possible particles with large
statistics
– Already tried
• charged p,K,p, deuteron, p0, e+(-) (inclusive), gamma (inclusive)
– On going but need much more statistics
• eta
• direct gamma
– inclusive gamma – [contribution from p0, eta (dominantly)]
• charm and bottom meson
– inclusive e+(-) – [contribution from p0 and eta dalitz decay (dominantly)]
– Seems to be hard work, but...
•
•
•
•
K0s
Lambda
resonances
penta-quark
• v1 on BBC (h=3-4)
• Correlation method for vn
• Cross section and HBT radii in-plane and out-plane
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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v2
Electron and Positron v2
200 GeV Au+Au Min. Bias
From talk of
Singo Sakai (Ph.D student at Tsukuba Univ.)
at JPS autumn meeting 2003 and DNP2003
pT[GeV/c]
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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Photon v2
v2
200 GeV Au+Au Min. Bias
pT [GeV/c]
From DNP2003 talk
Saskia Mioduszewski,
Edouard Kistenev, and
ShinIchi Esumi
Masashi Kaneta, RBRC, BNL
Heavy Ion Tea in Nuclear Science Division, LBNL (2003/11/5)
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