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PHENIX measurements of low momentum direct photon radiation

Author
Adare A. University of Colorado, USA
Finger Miroslav, prof. Ing. DrSc. Faculty of Mathematics and Physics, Charles University in Prague
Finger Michael, M.Sc. CSc. Faculty of Mathematics and Physics, Charles University in Prague, JINR Dubna
Afanasjev , Dr. JINR
et al.  different institutions

Year
2019

Scientific journal
NUCLEAR PHYSICS A 982 763-766

Web


Abstract
The versatility of RHIC allowed the PHENIX collaboration to measure low momentum direct photons from small systems, such as p+p, p+A, d+Au at root s(NN) = 200 GeV as well as from large A+A systems, such as Au+Au and Cu+Cu at 200 GeV and Au+Au at 62.4 GeV and 39 GeV. In these measurements PHENIX has discovered a large excess over the scaled p+p yield of direct photons in A+A collisions, and a non-zero excess over the scaled p+p yield in central p+A collisions. Another PHENIX discovery is that at low-p(T) the integrated yield of direct photons, dN(gamma)/dy, from large systems follows a universal scaling as a function of the charged-particle multiplicity, (dN(ch)/d eta)(alpha), with alpha = 1.25. The observed scaling properties of direct photons from these systems show that the photon production yield increases faster than the charged-particle multiplicit

Cite article as:
A. Adare, M. Finger, M. Finger, . Afanasjev, . et al., "PHENIX measurements of low momentum direct photon radiation ", NUCLEAR PHYSICS A 982 763-766 (2019)