A-dependence of the charm production cross section in 300 GeV/c proton interactions

Abstract The A -dependence of the charm production cross section is determined by measuring the yield of prompt single muons in a beam-dump experiment, using a 300 GeV/ c proton beam on Al, Fe, and U targets. Assuming that the production cross section varies as A α , we obtain α(μ + ) = 0.79±0.12 and α(μ − ) = 0.76±0.13 in the kinematical region x F ≳0.1 of the charm.