Cadmium Zinc Telluride detectors for a next-generation hard X-ray telescope

We are currently developing Cadmium Zinc Telluride (CZT) detectors for a next-generation space-borne hard X-ray telescope which can follow up on the highly successful NuSTAR (Nuclear Spectroscopic Telescope Array) mission. Since launch of in 2012, there have been major advances area mirrors, and state-of-the-art mirrors improve NuSTAR's angular resolution ~1 arcmin Half Power Diameter (HPD) to 15" or even 5" HPD. Consequently, size detector pixels must be reduced match this resolution. This paper presents detailed simulations relatively thin (1 mm thick) CZT with hexagonal at next-neighbor distance 150 $\mu$m. The account non-negligible spatial extent deposition energy incident photon, include modeling spreading free charge carriers as they move toward electrodes. discuss methods reconstruct energies photons, locations where photons hit detector. show that recorded brightest pixel six adjacent suffices obtain excellent resolutions. simulation results being used guide design hybrid application-specific integrated circuit (ASIC)-CZT package.