dmitri kotchetkov (university of california at riverside) for phenix collaboration
DESCRIPTION
Study of Cronin effect and nuclear modification of strange particles in d-Au and Au-Au collisions at 200 GeV in PHENIX. Dmitri Kotchetkov (University of California at Riverside) for PHENIX Collaboration. Quark Matter’04, Oakland, January 16 th , 2004. Strangeness at PHENIX. Motivations: - PowerPoint PPT PresentationTRANSCRIPT
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Study of Cronin effect and nuclearmodification of strange particles in d-Au and Au-Au collisions at 200
GeV in PHENIX
Dmitri Kotchetkov (University of California at Riverside)
for PHENIX Collaboration
Quark Matter’04, Oakland, January 16th, 2004.
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Strangeness at PHENIX
Motivations:
Strange particles as a tool to quantify the effects of medium modification
Strangeness observables to look into initial (gluon saturation) or final state (quark recombination, flow)
Effects of strangeness on energy loss
PHENIX ongoing analyses:
single
K,K
KK ee
S0K p p
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Nuclear enhancement and suppression
)peripheral(N/)peripheral(Yield
)central(N/)central(YieldR
coll
collCP
Parallel Session talk “/K/p production andCronin effect from p-p, d-Au and Au-Aucollisions at 200 GeV”by Felix Matathias
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Mesons vs. baryons or heavier vs. lighter?
In central Au-Au collisions:
No suppression of protons at Pt > 2.0 GeV Suppression of 0 up to measurement limits (~10
GeV)
In central d-Au collisions:
Nuclear enhancement (Cronin) is larger for protons
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How strangeness affects nuclear modification?
Effect of strange quarks on Rcp
Strange baryons and antibaryons vs. strange mesons (number of quarks)
Mass dependence of Rcp among strange particles
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Drift Chambers
Pad Chambers
PbSc ElectromagneticCalorimeter
Beam-BeamCounters
Time of flightCounters
900 450
5.1m2m
Beam direction
Detectors
0.35…+0.35
West Arm East Arm
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Hadron’s time of flight
In Time of flight Counters (TOF):In Electromagnetic Calorimeter (EMC):
time of flight resolution:TOF: 115 ps EMC: 700 ps (average)
function of energy of a cluster
P+
P-K-
K+
+
-
P+
P-
K+
K-
-
+
time of flight (ns)time of flight (ns)
charg
e/m
om
en
tum
(c/
GeV
)
charg
e/m
om
en
tum
(c
/GeV
)
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high asymmetry of decay mean P of from decay equals 0.3 GeV detect protons in high resolution TOF (up to 3 GeV) reconstruct protons into pairs with any hadron detected
either in TOF or EMC event mixing technique to build a combinatorial
background
reconstruction
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p invariant mass from d-Au collisions
From 63 x 106 minimum bias d-Au collisions:Counts = 24395+/-373(stat) barCounts = 9744+/-229(stat)
invariant mass (GeV/c2)
invariant mass (GeV/c2)
S/B = 1/5
barS/B = 1/4
65BS
S
43BS
S
counts/2.5(MeV/c2)
counts/2.5(MeV/c2)
Signal+BackgroundBackground
Signal
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From 20 x 106 minimum bias Au-Au collisions:Counts = 62786+/-1580(stat) barCounts = 48377+/-1358(stat)
counts /5(MeV/c2)
counts /5(MeV/c2)
S/B = 1/33
barS/B = 1/33
43BS
S
38BS
S
Signal
Signal+BackgroundBackground
invariant mass (GeV/c2)
invariant mass (GeV/c2)
p invariant mass from Au-Au collisions
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Detector acceptance normalization
Single particle generator (K0S, , e t.c.)
Simulation of PHENIX detector response Extract particle yields as for real data
Pt (GeV/c)
K0S
Pt (GeV/c)
acceptance acceptance
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and -bar Pt spectra in d-Au Minimum bias collisions at 200 GeV
Pt (GeV/c)
1/N
evt 1
/2
1/m
t dN
2/d
mtd
y
(GeV
/c)-
2
Only statistical errors are shown
PHENIX Preliminary
Poster Strangeness 5Arkadij Taranenko
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-> K+K- channel identify kaons either in TOF or EMC event mixing technique to build a combinatorial
background
reconstruction
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K+K- invariant mass from Au-Au
collisions
From 19 x 106 minimum bias Au-Au collisions:
Counts = 5560+/-240(stat) S/B = 1/8.5
counts/1(MeV/c2)
Posters:Strangeness 14by Charles Maguire
Flow 7 by DebsankarMukhopadhyay
counts/1(MeV/c2)
invariant mass (GeV/c2)
invariant mass (GeV/c2)
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Minimum bias eventsdN/dy=1.340.09(stat) 0.20(syst)T=366 11(stat) 18(syst) MeV
0-10%
10-40%
40-92%
1/2
mT d
N/d
mTd
y (G
eV
/c2)-
2
MT(GeV/c2)
PHENIX
K+K-
mt spectra in Au-Au collisions at 200 GeV
0-10% on correctscale, others offset by factors of 10
Parallel Session talk “Light vectormesons () in d-Au collisions in PHENIX”by Richard Seto
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Cronin effect in d-Au collisions
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Rcp of identified hadrons (0-20% d-Au central collisions) at 200 GeV
Only statistical errors shown for
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Rcp of identified hadrons (20-40% d-Au central collisions) at 200 GeV
‘s Rcp modification is very similar to one of the proton
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Rcp of identified hadrons (40-60% d-Au central collisions) at 200 GeV
Mass of is close to one of a proton
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Nuclear modification in Au-Au collisions
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Rcp of identified hadrons (0-10% Au-Au central collisions) at 200 GeV
pt (GeV/c)
Rcp
pp KK
0
nucl-ex/0307022
(0-10%)/(60-92%)
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Rcp of (0-10% Au-Au central collisions) at 200 GeV
Mass of is close to one of a proton
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Summary
Are differences in Rcp attributable to mass or quark number?
There is no evidence for mass dependence of Rcp
Strangeness seems to have no effect on Rcp
There is a difference in Rcp for mesons and baryons(see STAR results of ’s Rcp in Au-Au)
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Outlook
Rcp results from K0S and from (Au-Au)
Analysis of multi-strange baryons ( and others)
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Extracted K0S signal
invariant mass (GeV/c2)invariant mass (GeV/c2)
counts/2.5(MeV/c2)
From 48.85 x 106 minimum bias p-p collisions: Counts = 16630+/-605(stat) 62.20 x 106 minimum bias d-Au collisions: Counts = 116397+/-2627(stat)
d-Aup-p
counts/2.5(MeV/c2)