Perspectives of thermal photon measurements in heavy ion collisions at NICA

Evgeny Kryshen,Dmitry Kotov,Victor Riabov,Mikhail Malaev,Dmitry Ivanishchev,Yuriy Ryabov

doi:10.1051/epjconf/201922202006

Abstract

The main goal of the future NICA-MPD experiment is studying the dense baryonic matter produced in heavy-ion collisions in the energy range 4-11 GeV and searching for signs of the phase transition between hadronic matter and deconfined quark-gluon plasma. Measurements of soft thermal photon yields and collective flow can significantly extend the physics program of the MPD experiment, allowing one to probe the temperature and the level of thermalizaion of the medium created in heavy ion collisions at NICA energies. The optimal method to measure soft photons is to register photon conversions in the material of the tracking system. In this contribution, recent RHIC and LHC results on thermal photon spectra and flow will be presented. Motivation and feasibility of thermal photon measurements with the conversion method in the projected MPD setup will be discussed.

Highlights

The phase diagram of nuclear matter, studied in heavy ion collisions, is usually expressed in terms of the temperature and the baryon chemical potential of the medium
The conversion method usually provides much better resolution at low transverse momenta compared to the calorimetric method. Both photon detection methods will be explored in the future MPD experiment [8] at the NICA collider [9] that densities using Au-Au icsoalilmisieodnos ninththeesteundeiregsyorfafnugneda4m
We present feasibility studies on the measurement of so√ft photons and neutral mesons reconstructed via photon conversions in Au+Au collisions at sNN = 4 and

Summary

Introduction

The phase diagram of nuclear matter, studied in heavy ion collisions, is usually expressed in terms of the temperature and the baryon chemical potential of the medium. The conversion method usually provides much better resolution at low transverse momenta compared to the calorimetric method Both photon detection methods will be explored in the future MPD experiment [8] at the NICA collider [9] that densities using Au-Au icsoalilmisieodnos ninththeesteundeiregsyorfafnugneda4m

Differential yields of neutral mesons and direct photons

Photon conversion probability and reconstruction efficiency

Reconstruction of neutral mesons

Elliptic flow measurements

Findings

Conclusions