Gamma-Ray Energy Deposition in Silicon Detectors

Calculations of the gamma-ray energy deposition spectrum have been performed for a silicon ionization dosimeter based on a silicon surface barrier detector. The technique used was a coupled photon-electron transport calculation using the three-dimensional Monte Carlo code, SANDYL. Comparison of calculated pulse-height spectra and measurements of standard calibrated gamma sources demonstrated the need to take into account the nonuniformity of the charge collection efficiency in the device. To this end, measurements were made of the radial dependence of the charge collection efficiency and sensitive volume. These results yielded an improved model and improved agreement between calcullation and experiment.