f- meson production in d - au collisions at √s = 200 gev
DESCRIPTION
Dipali Pal Vanderbilt University (for the PHENIX Collaboration). f- Meson Production in d - Au Collisions at √s = 200 GeV. Outline. Physics motivation PHENIX experiment Particle identification Data analysis f meson reconstruction Corrections - PowerPoint PPT PresentationTRANSCRIPT
Hot Quarks 2004, Taos Valley 1
Meson Production in d Au Collisions at √s = 200 GeV
Dipali Pal
Vanderbilt University
(for the PHENIX Collaboration)
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Outline
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• Physics motivation• PHENIX experiment• Particle identification• Data analysis
meson reconstruction Corrections
• Results ( K+K- and e+e-)• Summary and outlook
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Physics motivation
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mesons
• Chiral symmetry restoration and medium effects - mass shift, width broadening - branching ratios in K+K- and e+e- decay channel Simultaneous measurement of K+K- and e+e-
• Strangeness production - meson yield
• Particle production mechanism - Rcp, elliptic flow
• Au – Au & d – Au collisions– Distinguish between hot and cold partonic matter– Evolution of medium properties with density and temperature– Probing nuclear effects
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K+K-
Minimum-bias|zVertex| < 30 cm
Nevt = 54 M
Tracking : DC – PC1 – PC3 Momentum
PHENIX Setup
Collision vertex and centrality: Beam-beam Counter
e+e-
Electron identification: RICH + EMC || < 0.35, = 90o, both arms
Kaon identification: TOF: || < 0.35, = 45o PbSc (East): || < 0.35, = 45o
PbSc (West): || < 0.35, || = 90o
K-
K+K+K-
K+K-
K+
K
-
e+e-
ERT_Electron trigger|zvertex| < 30 cmNevt (ERT) = 31M 1.9 G Minimum bias
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Kaon identification
Time of flight (TOF):0.3 < p (GeV/c) < 2t = 130 ps
PbSc East and West:0.3 < p(GeV/c) < 1.0t ~ 450 ps
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Electron identification
Energy / Momentum
Electron PID cutsNRICH PMT 20.5<E/p<1.5 E - from EMCp from tracking
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Data analysis and corrections
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• Same event K+K- and e+e- invariant mass distributions (R).
• Combinatorial background (CB) Event mixing within same centrality and Zvertex
Normalization to 2√N++N—
• Signal = R - CB
• Acceptance correction: PHENIX Single particle Monte-Carlo simulation - Event generation + Detector hit + Detector response + offline analysis
• Other experimental quality control correction: Run (time) dependent corrections
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Invariant mass distributions
MixedBackground
Co
un
ts p
er 1
0 M
eV/c
2
e+e- invariant mass (GeV/c2)
K+K- @ d – Au, √sNN = 200 GeVK+ and K- are selected from TOF
e+e- @ d – Au, √s = 200 GeV
S ~ 120S/B = 1/4
= 4.409 ± 0.711 MeV/c2
Co
un
ts p
er 1
MeV
/c2 b
in
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meson transverse mass spectra (I)
)(syst 0.00950.0092 )stat ( 0.0092 0.0468
dydN
mT(GeV/c2)
e+e-
1/2
mT d
N/d
mTd
y (G
eV
/c2)-
2
PHENIX Preliminary PHENIX Preliminary
Fitted with exponential function in mT
)23(syst31(stat)414T
dN/dy=0.0560.015(stat) 50%(syst)T=326 94(stat) 53%(syst) MeV
PHENIX PreliminaryPHENIX Preliminary
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meson transverse mass spectra (II)SPS result
Central Pb-Pb 158 A GeV
49: K+K- T = 305 MeV dN/dy ~ 2.35
NA50: T = 227 MeV No specific quote of dN/dyIntegrating the mT spectrum gives dN/dy ~ 13
D. Rohrich et al, J Phys. G 27 (2001) 355
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1/2
mT d
N/d
mTd
y (G
eV
/c2)-
2
Minimum-bias mT distribution of
MT(GeV/c2)Overall fitdN/dy~ 0.0485T~4082/DOF=6.7/7
dN/dy T
yields in d-Au collisions in K+K- and e+e- channels are consistent witheach other
K+K-
K+K-
e+e-e+e-
K+K-
e+e-
PHENIX Preliminary PHENIX Preliminary PHENIX Preliminary
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Comparison between yields in d-Au and Au-Au collisions
( K+K- )
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yield increases from d-Au to Au-Au system
Inverse slope remains constant in Au-Au and d-Au collisions.
(Preliminary)(Preliminary)
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Factor of ~4 more statistics is now available by including the PbSc detectors in east and west arm. Scope of centrality dependence studies.
Invariant mass spectra from TOF and PbSc analysis
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Full east arm ( TOF + PbSc) West arm (PbSc)
Work in progressWork in progress
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Summary
• First simultaneous measurement of K+K- and e+e- in d-Au collisions at RHIC.
K+K-
)(syst 0.00950.0092 )stat ( 0.0092 0.0468
dydN
dN/dy=0.056.015(stat) 50%(syst)T=326 94(stat) 53%(syst) MeV
e+e-
Consistent with each other within errors.
• yield jumps from d-Au minimum-bias to Au-Au peripheral collisions. Then it increases slowly upto Au-Au mid-central, finally saturates.
)23(syst31(stat)414T
(PHENIX Preliminary) (PHENIX Preliminary)
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Outlook
• Extended K+K- measurement in d-Au collisions with kaons identified with PbSc modules.
Total yield increases by almost a factor of 4.
Better understanding of the systematics is possible.
Centrality dependence of yield
Particle ratio
Rcp measurements.