The Cosmic Diffuse Gamma-Ray Flux at 10 MeV

Abstract

The cosmic diffuse -ray flux at 10 MeV has been measured by a spark-chamber technique on a balloon flight at 3 g cm-2, 4.5 GV geomagnetic cutoff. The flux at 10 MeV is (8.0 t 4.5) x io-4 `s (cm2 5 sterad MeV) -1 where the error is due to the uncertainty in the atmospheric flux. The measured value is an order of magnitude above the extrapolation of the power law which holds below 1 MeV. Subject headings: cosmic background radiation - gamma rays