Development of an improved, scalable, mosaicked CdZnTe (CZT) imaging detector plane architecture for high energy astrophysics

The High Resolution Energetic X-Ray Imager (HREXI) is a scalable detector plane architecture that utilizes the NuSTAR ASIC (NuASIC) at the front end to readout large arrays of 2 cm × 2 cm, 3 mm thick pixelated CdZnTe (CZT) detectors; each with a monolithic cathode deposited to the upper surface and a 32 × 32 array of 550 μm pads distributed across the lower anode surface with a 604.8 μm pitch. The CZT anode pads are bonded directly to the inputs of the NuASIC located on the upper surface of the silicon die with an identical pattern. The architecture of the detector plane is hierarchical and consists of 3 primary layers: (1) the detector crystal array (DCA) board, which support the operation of a 2 × 2 array of NuASIC-coupled CZT detectors; (2) the FPGA mezzanine board (FMB) that supports the operation of a single FPGA capable of supporting the operation and readout of a 2 × 2 array of DCAs; and (3) the detector module board (DMB) which accepts data streams and controls up to 8 chains of 8 FMBs, a total of 1024 individual detectors with an active area of approximately 4096 sq. cm. Here we present the qualification, performance and applications of this system for astronomy.