Centrality dependence of low-momentum direct-photon production in Au plus Au collisions at root s(NN)=200 GeV

Title
Centrality dependence of low-momentum direct-photon production in Au plus Au collisions at root s(NN)=200 GeV
Authors
김용균
Keywords
NUCLEAR COLLISIONS; EMISSION; DETECTOR
Issue Date
2015-06
Publisher
AMER PHYSICAL SOC
Citation
PHYSICAL REVIEW C, v. 91, NO 6, Page. 1-11
Abstract
The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au + Au collisions at root s(NN) = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e(+)e(-) pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT. We find an excess of direct photons above the N-coll-scaled yield measured in p + p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range 0.6-2.0 GeV/c. While the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N-part(alpha), where alpha = 1.38 +/- 0.03(stat) +/- 0.07(syst).
URI
https://journals.aps.org/prc/abstract/10.1103/PhysRevC.91.064904http://hdl.handle.net/20.500.11754/25681
ISSN
0556-2813; 1089-490X
DOI
http://dx.doi.org/10.1103/PhysRevC.91.064904
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > NUCLEAR ENGINEERING(원자력공학과) > Articles
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