Photons from Pb-Pb Collisions at CERN SPS
  High energy photon emission rate from matter created in Pb + Pb collisions at CERN SPS energies is evaluated. The evolution of matter from the initial state up to freeze-out has been treated within the framework of (3+1) dimensional hydrodynamic expansion. We observe that the photon spectra measured by the WA98 experiment are well reproduced with hard QCD photons and photons from a thermal source with initial temperature ~ 200 MeV. The effects of the spectral changes of hadrons with temperature on the photon emission rate and on the equation of state are studied. Photon yield for Au + Au collisions at RHIC energies is also estimated. 
Jan-e Alam, Sourav Sarkar, T. Hatsuda, Tapan K. Nayak and Bikash Sinha