Measurement of the Nuclear Dependence of Direct Photon and Neutral Meson Production at High Transverse Momentum by Negative 515 Gev/c Pions Incident on Beryllium and Copper Targets.

The nuclear dependence of inclusive direct photon production and inclusive neutral meson production by a 515 GeV/cpi^- beam has been measured using data collected by the E706 experiment during the 1990 fixed target run at the Fermi National Accelerator Laboratory. The experiment utilized a finely segmented liquid argon calorimeter and a high precision charged particle spectrometer to make precision measurements of inclusive direct photon, neutral pion, and eta production in the rapidity interval from { -0.75}<y<0.75. The pi^0 data is reported for the P_ T range from 0.6 GeV/c to 12 GeV/c, while the eta data is reported for the range from 3.5 GeV/c to 7.0 GeV/c. The direct photon nuclear dependence results are reported for the range from approximately 4.0 GeV/c to 8.5 GeV/c. The data from the beryllium and copper targets have been fit using the parameterization sigma _ A=sigma_0times{rm A}^alpha. The neutral meson results are in good agreement with previous charged meson results. The direct photon results are consistent with no anomalous enhancement.