Characterization of Redlen CZT detectors for hard x-ray astronomy

We present the results of ongoing characterization of Cadmium Zinc Telluride (CZT) semiconductors produced by Redlen Technologies for use in X-ray astronomy. The fully fabricated hybrid detectors consist of CZT crystals with a collecting area of 2cm x 2cm and thickness of 3mm mounted on a custom ASIC originally designed for the Nuclear Spectroscopic Telescopic Array (NuSTAR) mission, which launched in 2012. We present the results of spectral calibration using 57Co, 155Eu, and 241Am sources and determine optimal operating conditions such as temperature and bias voltage. In addition, we determine the charge transport properties of the material. We compare the characteristics of the Redlen CZT detectors to those of the CZT detectors produced by eV Products aboard NuSTAR and to Cadmium Telluride (CdTe) detectors with the same hybrid architecture. Finally we discuss the viability of the Redlen for X-ray astronomy in the NuSTAR band and above.