Abstract: A direct conversion broad band x-ray/gamma-ray photocathode having at least one layer functioning as an efficient x-ray or gamma-ray absorber and another layer functioning as an efficient transmission secondary electron emitter for providing both high detection efficiency and high spatial resolution, for use in either a radiation detection environment or an image intensification environment.

Abstract: A radiation measuring instrument including a fast charge digitizer and a digital data acquisition system has been developed. The fast charge digitizer includes a charge integrator connected to a conventional ionization chamber which generates an output current in proportion to ionizing radiation exposure rate. The charge integrator has an output connected to a comparator which is switched from a high state to a low state when the output of the integrator goes above the comparator threshold. The comparator output is connected to a bistable multivibrator consisting of two non-retriggerable one shot multivibrators connected in a feedback configuration. As long as the comparator output is in the low state, the bistable multivibrator generates a train of pluses which are fed back through an analog switch and a high megohm resistance to the input of the integrator.