Exploring sub-MeV sensitivity of AstroSat–CZTI for ON-axis bright sources

The Cadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat is designed for hard X-ray imaging and spectroscopy in the energy range of 20–100 keV. CZT detectors are 5-mm thickness hence have good efficiency Compton interactions beyond 100 polarisation analysis using CZTI relies on such events been verified experimentally. same can also be used to extend up 380 Further, it has observed that about 20% pixels detector plane low gain, they excluded from primary spectroscopy. If these included, then spectroscopic capability extended 500 keV further 700 with a better gain calibration future. Here we explore possibility as well ON-axis bright sources. We demonstrate this technique Crab observations its sensitivity.