Calibration of the NEAR gamma-ray spectrometer

The gamma-ray spectrometer onboard the Near Earth Asteroid Rendezvous spacecraft will measure gamma rays from the surface of 433 Eros in the 100-keV to 10-MeV energy region. Detection of characteristic gamma-ray emissions from such elements as O, Si, Fe, Ca, Ti, Mg, Al, H, K, Th, and U will allow the determination of abundances of these geologically important elements. Spatial resolution will be large, but the emission detected will originate from a volume of material down to depths of 10-20 cm below the surface. These measurements will make it possible to relate Eros to known meteorite classes and to relate these to geological processes on Eros. The calibration measurements and analysis procedures that are described will be needed for the reduction and analysis of gamma-ray data collected during the mission. In addition to geochemical measurements, the gamma-ray detector is used to detect gamma-ray bursts and forms part of the interplanetary network of gamma-ray detectors used to determine the source positions of gamma-ray bursts. (C) Academic Press.