Shuttle flight test of an advanced gamma-ray detection system

The Space Astronomy Laboratory plans to fly an advanced gamma-ray spectrometer aboard a future Shuttle flight. The "GRAD' spectrometer employs a new bismuth germanate (BGO) anticompton shield and n-type high purity germanium detector. BGO, because of its high atomic number, requires only 1/12 the volume and 1/6 the weight of an equally sensitive sodium iodide crystal. The n-type germanium detector is at least 25 times more resistant to neutron radiation damage than a conventional detector and has a very broad spectral response of 5 keV to 10 MeV. Neither of these materials has been subjected to the space environment as working components of a detector system. The radioactivation of the new detector materials by cosmic rays and fast neutrons, as well as other effects of launching, landing and operation in the space environment on the detector system will be monitored and calibrated. Early information on gamma-ray background from activation of the shuttle itself will also be obtained. In addition to the technological information derived from the experiment, high energy-resolution spectra of the Sun and the galactic center will be taken.