Upper Limit to the Cosmic Diffuse Gamma-Ray Flux at 40-100 MeV

Abstract

Atmospheric growth curves from halloon-borne spark chambers at 5 to 1.3 mb have been used to set upper limits on the cosmic diffuse -ray flux of 1.6 X 10- and 1.0 X 10-6 `s (cm2 s sterad MeV) - 1 at 40 and 100 MeV. When combined with the positive results at 10 MeV of Kuo et a!. or Trombka et a!., these limits imply an E-3 spectrum between 10 and 100 MeV. Subject headings:cosmic background radiation - gamma rays