Monte Carlo simulation of multiple scattering in Compton spectroscopy.

The Compton scattered photons from a scattering medium can be analyzed in a Compton spectrometer and the primary energy spectrum derived using the Compton equation. Since the reconstruction algorithm assumes that only singly-scattered photons from the scatterer are detected, multiply-scattered photons introduce errors into the measurements unless they can be accurately corrected for. In this work, a Monte Carlo collision density estimator was used to determine the contribution from photons multiply-scattered from a Lucite scatterer in the form of a square rod. The ratio of multiply- to singly-scattered photons was determined for rod thicknesses from 0.5 to 5 mm and photons of energy 20 to 110 keV. The ratio in percent can be well approximated as a linear function of energy with slope 2.2. For thicknesses below 2 mm, the ratio is less than 5% at all energies.