Directional High Energy Gamma-Ray Counter

Abstract

A directional Čerenkov counter has been developed for detection of energetic gamma rays from balloons and satellites. It is sensitive to photons whose directions lie within a 10° cone. It is completely insensitive to backward fluxes and almost completely insensitive to charged particles. Several different versions of the system have been constructed, and tested in bremsstrahlung beams. The angular resolution has also been indirectly confirmed by using the device to count cosmic ray muons at sea level.