The cosmic γ-ray spectrum near 1 MeV observed by the ERS-18 satellite

Abstract

In this paper, we wish to report new data obtained on the total, or omnidirectional, cosmic γ-Ray flux in the 250 keV to 6 MeV range. Flux in this energy range up to 2 MeV was first detected on the Ranger 3 (Metzger et al., 1964) and has been confirmed up to 0.5 MeV and extended to lower energies by a series of rocket (Gorenstein et al., 1969; Seward et al., 1967) and balloon measurements (Bleeker et al., 1966; Rocchia et al., 1967). Observation of the spectrum at higher energies has become of considerable importance since the recent successful detection of galactic 100 MeV γ-Rays by the OSO-3 (Clark et al., 1968).