Organic-scintillator compton gamma ray telescope

Abstract

Apparatus and methods for imaging sources of gamma rays with a large area, comparatively low-cost Compton telescope (). The Compton telescope () uses multiple layers () of low-cost organic solid plastic or liquid scintillator, arranged in large arrays of identical scintillator pixels (). Photodiodes, avalanche photodiodes (), or solid-state photomultipliers are used to read out the fluorescent pulses from scintillator pixels (). Multiple scintillator pixels () are multiplexed into a few fast digitizers () and a few fast FPGA programmable digital microprocessors (). Selection rule methods are presented for processing multiple near-simultaneous gamma ray collisions within the Compton telescope () to identify trackable events that yield gamma ray image data of interest. A calibration method achieves improved energy resolution along with (x,y) position information in pixels () made of organic scintillator materials with multiple photodetectors (). Synchronization trigger signals are used from a pulsed neutron source () to maximize the signal-to-background ratio for prompt gamma neutron activation analysis (PGNAA) of objects at greater than 2 meters range, where such trigger signals are based on the estimated range to PGNAA sources and neutron time-of-flight.