Electron Scattering Effects in Typical Cosmic Ray Telescopes

Laboratory measurements have been made of the response of two typical cosmic ray detector systems to electrons between 0.2 and 2.0 MeV. The detector systems investigated were included in the Caltech Solar and Galactic Cosmic Ray Experiment aboard NASA´s OGO-VI spacecraft and the Chicago/ Caltech Low Energy Cosmic Ray Experiment aboard OGO-IV. Working laboratory versions of each of these particle telescopes were exposed to the monoenergetic electron beam from a magnetic spectrometer. The results of pulse height and counting rate measurements indicate that electrons scattered from the anti-coincidence cup comprise about 25% of the total number arriving at the top of the detector stack. In certain cases, the contribution of these scattered particles to the total number of electrons detected can reach 65%. Suggestions are made for applying these results to other detector systems.