Radiation measurements to 1500 kilometers altitude at equatorial latitudes

Abstract

Three instrument packages containing Geiger tubes were flown into the inner Van Allen belt to altitudes up to 1500 km. Various absorber thicknesses were used to obtain range spectra for penetrating particles. Magnetic separation of electrons and protons was performed on counters with absorber thicknesses ranging from 1.7 mg/cm2 of mica to 36 mg/cm2 of aluminum. The electron spectrum observed with counters having electron energy thresholds of 30, 160, 190, and 460 kev appears considerably softer than a neutron beta-decay spectrum. Counts in counters with higher thresholds are assumed to be due to trapped protons and the measurements are compared with those obtained with nuclear emulsion experiments on similar trajectories. Absolute flux values are reported.