A1 Journal article (refereed)
Low-pT direct-photon production in Au+Au collisions at √sNN = 39 and 62.4 GeV (2023)

PHENIX Collaboration. (2023). Low-pT direct-photon production in Au+Au collisions at √sNN = 39 and 62.4 GeV. Physical Review C, 107(2), Article 024914. https://doi.org/10.1103/PhysRevC.107.024914

JYU authors or editors

Publication details

All authors or editors: PHENIX Collaboration

Journal or series: Physical Review C

ISSN: 2469-9985

eISSN: 2469-9993

Publication year: 2023

Publication date: 24/02/2023

Volume: 107

Issue number: 2

Article number: 024914

Publisher: American Physical Society (APS)

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevC.107.024914

Publication open access: Not open

Publication channel open access: 

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/86577

Publication is parallel published: https://arxiv.org/abs/2203.12354

Abstract

The measurement of direct photons from Au+Au collisions at √sNN=39 and 62.4 GeV in the transverse-momentum range 0.4<3Gev/c is presented by the PHENIX collaboration at the BNLRelativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon pT spectra for different center-of-mass energies and for different centrality selections at √sNN=62.4 GeV is scaled with (dNch/dη)α for α=1.21±0.04. This scaling also holds true for direct-photon spectra from Au+Au collisions at √sNN=200 GeV measured earlier by PHENIX, as well as the spectra from Pb+Pb at √sNN=2760 GeV published by ALICE. The scaling power α seems to be independent of pT, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to pT of 2 Gev/c. The spectra have a local inverse slope Teff increasing with pT of 0.174±0.018Gev/c in the range 0.4<1.3Gev/c and increasing to 0.289±0.024Gev/c for 0.9<2.1Gev/c. The observed similarity of low-pT direct-photon production from √sNN=39 to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.

Keywords: particle physics; nuclear physics; photons

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2023

Preliminary JUFO rating: 2