The objective of the experiment (E8) was to study the origin and the distribution mechanism of low-energy electrons and protons. The instrument, a magnetic spectrometer, consisted of six semiconductor detectors with the field of view in the plane of the ecliptic. Species separation was achieved by an inhomogeneous magnetic field oriented perpendicular to the particle path. Four electron and two proton detectors measured electrons from 17 to 835 keV and protons from 21 to 677 keV. The proton measurements were made with a two-detector telescope employing coincidence and anticoincidence logic. Both particle species were measured in 16 energy channels through pulse-height analysis. For further information see pp. 261-263 of Raumfahrtforschung, v. 19, n. 5, 1975.