The STAR experiment

Abstract:  Background conversion probability using identified pi0 sample, take 2 we have used identified pi0 and eta decays to estimate background conversion rates.  It is important to cross check that the conversion rate for a single photon, isolated in a single calorimeter cell, agrees with the conversion rate expected based on the thickness of the radiator.  This was shown to work well for single photons isolated from eta decays, and for the pair of photons identified in both eta and pi0 decays.  However,  when we examine the conversion rate for single photons isolated in a tower from a pi0 decay, the conversion rate does not agree with the 1-photon hypothesis.  In this study, we show that the background beneath the pi0 peak does not explain this discrepancy.