Campus Units

Physics and Astronomy

Document Type

Article

Publication Version

Published Version

Publication Date

11-2018

Journal or Book Title

Physical Review C

Volume

98

Issue

5

First Page

054902

DOI

10.1103/PhysRevC.98.054902

Abstract

We measured direct photons for pT<5GeV/c in minimum bias and 0%–40% most-central events at midrapidity for Cu+Cu collisions at √sNN=200 GeV. The e+e− contribution from quasireal direct virtual photons has been determined as an excess over the known hadronic contributions in the e+e−mass distribution. A clear enhancement of photons over the binary scaled p+p fit is observed for pT<4 GeV/c in Cu+Cu data. The pT spectra are consistent with the Au+Au data covering a similar number of participants. The inverse slopes of the exponential fits to the excess after subtraction of the p+p baseline are 285±53(stat)±57(syst)MeV/c and 333±72(stat)±45(syst)MeV/c for minimum bias and 0%–40% most-central events, respectively. The rapidity density, dN/dy, of photons demonstrates the same power law as a function of dNch/dη observed in Au+Au at the same collision energy.

Comments

This article is published as Adare, A., S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander et al. "Low-momentum direct-photon measurement in Cu+ Cu collisions at s N N= 200 GeV." Physical Review C 98, no. 5 (2018): 054902. DOI: 10.1103/PhysRevC.98.054902. Posted with permission.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

Included in

Nuclear Commons

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