Characterization of the Si(Li) detector for Monte Carlo calculations of beta spectra

A precise model of a Si(Li) detector ORTEC model SLP-06165P-OPT-0.5 was created for beta spectra calculations using the Monte Carlo (MC) code MCNPX. Detector parameters were determined from X-ray radiograms obtained with a film and a Timepix detector. The MC model of the detector was validated by comparison of calculated and experimental full-energy peak efficiencies in the energy range from 5 to 136 keV using a range of point-like photon emitting radionuclide standards. A comparison of measured and calculated beta spectrum of a radionuclide Pm-147 is presented.