Also onboard was an MIT gamma-ray instrument. It operated continuously for about 16 months, at which time the last spacecraft tape recorded failed. The detector was a counter telescope. The multilayer scintillation detector consisted of layers of CsI and plastic. The directional Cerenkov counter was a 3x3 in cylinder of lucite. The energy detector contained several layers of NaI, sandwiched by layers of tungsten. The entire detector was enclosed by plastic scintillator detectors. It was sensitive to gamma-rays above 50 MeV.
The gamma-ray instrument registered 621 events attributed to cosmic gamma- rays above 50 MeV. A complete sky survey showed that the celestial distribution of gamma-rays is highly anisotropic, being concentrated along the galactic equator. In addition, an extended region around the galactic center showed a higher measured intensity.
ReferencesPelling, R. 1971, Ph.D. dissertation thesis, University of California (San Diego).
Peterson et al 1966, Phys Rev Let 16, 142.
Peterson et al 1966, ApJ 145, 962.
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