Direct Photon Production from Negative and Positive Pions and Protons at 200 GeV/C

摘要

Direct photon production has been studied in the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to photons with 2.5 less than or equal to P/sub T/ less than or equal to 6 GeV/c and center-of-mass rapidity -0.4 less than or equal to y* less than or equal to 1.2. Preliminary results from incident pions and protons are given and compared to previous data. Preliminary results on the gamma / pi exp 0 ratio and on the charge asymmetry between pi exp - and pi exp + induced direct photons are presented and discussed in the framework of QCD predictions. 10 refs., 7 figs. (ERA citation 10:047543)