Room temperature semiconductor detectors for hard x-ray astrophysics

Room temperature cadmium zinc telluride (CdZnTe) and mercuric iodide (HgI2) semiconductor hard X-ray detectors are currently being evaluated at NASA Goddard Space Flight Center for use in future balloon and satellite applications. PoRTIA, a small engineering prototype hard X-ray (20 - 150 keV) balloon instrument will contain both a CdZnTe and a HgI2 detector, each 6.5 cm2 x .15 - .2 cm and sharing the same 5 degree(s) field-of-view. PoRTIA will be launched from Alice Springs, Australia in the Spring of 1995 as a piggyback instrument aboard the GRIS balloon payload. PoRTIA will provide valuable information about detector efficiency, durability and material dependent detector background components at balloon altitudes as it observes the Crab Nebula. In addition, a CdZnTe research and development program has been initiated to develop the capability to produce improved CdZnTe detectors for astrophysics applications. The work at Goddard continues in an effort to develop CdZnTe detectors with improvements in electronics, contacts and packaging methods.