Campus Units

Physics and Astronomy

Document Type

Article

Publication Version

Published Version

Publication Date

4-2010

Journal or Book Title

Physical Review Letters

Volume

104

Issue

13

First Page

132301

DOI

10.1103/PhysRevLett.104.132301

Abstract

The production of e(+)e(-) pairs for m(e+e-) < 0.3 GeV/c(2) and 1< p(T) < 5 GeV/c is measured in p + p and Au + Au collisions at root s(NN) = 200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au + Au collisions, the excess of the direct photon yield over p + p is exponential in transverse momentum, with an inverse slope T = 221 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T-init similar to 300-600 MeV at times of similar to 0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at similar to 170 MeV.

Comments

This article is published as Adare, Ad, S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander et al. "Enhanced production of direct photons in Au+ Au collisions at s N N= 200 GeV and implications for the initial temperature." Physical Review Letters 104, no. 13 (2010): 132301. DOI:10.1103/PhysRevLett.104.132301. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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