A Search for Primary Cosmic Gamma-Radiation. II. Low Energy Radiation above and within the Atmosphere

Measurements are reported on the intensity of gamma-rays in the energy range 0.1 to 15 Mev, made in a series of rocket flights. The gamma-radiation was detected by anticoincidence in a bundle of Geiger counters. Registration of coincidences permitted a measurement of the intensity of charged particles, with the same geometry. The two quantities displayed a simultaneous maximum during flight, the counting rate of charged particles being ten times that of $\gamma$-rays at the maximum. A diurnal effect was looked for and not found. A theoretical treatment is given of the origin of the $\gamma$-radiation at the maximum. It is shown to be accountable for by bremsstrahlung of the electronic component and subsequent multiple Compton scattering. An estimate is given of the radiation due to annihilation of positrons followed by Compton scattering. This is shown to be only a few percent of the bremsstrahlung effect.