Measurement of photons via conversion pairs in Au+Au collisions at sqrt(s_NN) = 200 GeV with the PHENIX experiment at RHIC

TL;DR

This paper presents a method to measure direct photons in Au+Au collisions at RHIC by reconstructing e^+e^- pairs from photon conversions, aiming to identify thermal photon contributions indicative of the created hot matter.

Contribution

It introduces a novel technique to reconstruct direct photons through external conversion pairs, enhancing the ability to detect thermal photon signals in heavy-ion collisions.

Findings

Method successfully reconstructs photons via conversion pairs.

Potential to observe thermal photon excess in the specified p_T range.

Improves accuracy in direct photon measurement in heavy-ion experiments.

Abstract

Thermal photons can provide information on the temperature of the new state of matter created at RHIC. In the p_T region of 1--3 GeV/c thermal photons are expected to be the dominant direct photon source. Therefore, a possible excess compared to a pure decay photon signal due to a thermal photon contribution should be seen in the double ratio (gamma/gamma(pi^0))_{Measured}/(gamma/gamma(pi^0))_{Simulated}, if sufficient accuracy can be reached. We present a method to reconstruct direct photons by measuring e^+e^- pairs from external photon conversions.