A New Monte Carlo Assisted Approach to Detector Response Functions

Abstract

The physical mechanisms that describe the components of NaI,Ge, and SiLi detector response have been investigated using Monte Carlosimulation. The mechanisms described focus on the shape of the Compton edge,the magnitude of the flat continuum, and the shape of the exponential tailsfeatures. These features are not accurately predicted by previous Monte Carlosimulation. Probable interaction mechanisms for each detector responsecomponent is given based on this Monte Carlo simulation.Precollision momentum of the electron is considered when simulating incoherentscattering of the photon. The description of the Doppler broadened photonenergy spectrum corrects the shape of the Compton edge. Special attention isgiven to partial energy loss mechanisms in the frontal region of the detectorlike the escape of photoelectric and Auger electrons or low-energy X-rays fromthe detector surface. The results include a possible physical mechanismdescribing the exponential tail feature that is generated by a separate MonteCarlo simulation. Also included is a description of a convolution effect thataccounts for the difference in magnitude of the flat continuum in the MonteCarlo simulation and experimental spectra. The convolution describes anenhanced electron loss. Results of these applications are discussed.