Development of a Segmented n-Type Germanium Detector, and Its Application to Astronomical gamma-Ray Spectroscopy.

摘要

Extensive calculations and simulations have shown that the instrumental background in a coaxial germanium photon detector flown at balloon altitudes or in space, can be substantially reduced by segmenting the outer contact. The contact is divided into horizontal strips around the side of the detector, giving it many characteristics similar to that of a stack of planar detectors. By choosing different segment coincidence requirements in different energy ranges, one can obtain a factor of approx. 2 increase in sensitivity to spectral lines between 40 keV and 1 MeV, compared with an unsegmented detector. The reverse electrode configuration (using n-type germanium), with the p contact outside, is preferred for this application due to its thin dead layer and resistance to radiation damage in space. We are currently developing a small two-segment n-type detector to serve as a prototype for larger multi-segment devices. Results of this development effort and of detector tests will be presented. (ERA citation 08:052070)