Characterization of a pixelated Cadmium-Zinc-Telluride detector for astrophysical application

Charge sharing and charge loss measurements for a many-pixel, Cadmium-Zinc-Telluride (CdZnTe) detector are discussed. These properties that are set by the material characteristics and the detector geometry help to define the limiting energy resolution and spatial resolution of the detector in question. The detector consists of a 1-mm-thick piece of CdZnTe sputtered with a 16x16 array of pixels with a 300 micron pixel pitch (inter-pixel gap is 50 microns). This crystal is bonded to a custom-built readout chip (ASIC) providing all front-end electronics to each of the 256 independent pixels. These types of detectors act as precursors to that which will be used at the focal plane of the High Energy Replicated Optics (HERO) telescope currently being developed at Marshall Space Flight Center. With a telescope focal length of 6 meters, the detector needs to have a spatial resolution of around 200 microns in order to take full advantage of the HERO angular resolution. We discuss to what degree charge sharing degrades energy resolution through charge loss and improves spatial resolution through position interpolation.