An improved summing Compton gamma-ray spectrometer

A simple ad hoc analog computer using semiconductor logarithmic elements is used to examine the coincident pulse-pairs from a summing Compton spectrometer for compatibility with the Compton scattering equation for the particular scattering angle being used. With the aid of this circuit, the total absorption fraction of the spectrometer can be raised almost to 100% by identifying and rejecting electronically those coincidences in which some of the energy of the incident photon has escaped from either detector. At the same time, the polarization sensitivity of the Compton spectrometer is also improved since coincidences in which multiple scattering has taken place are rejected. The system can also be used to make the spectrometer telescopic, selecting electronically rather than by heavy collimators the incident direction of interest. The latter capability may be useful in situations where there is an omnidirectional flux. Though scintillation crystals have been used here to demonstrate the principle, the technique would be equally applicable (and perhaps most useful) in a light and compact Compton spectrometer using semiconductor detectors.Peer reviewed: YesNRC publication: Ye