Accurate efficiency characterization of a BEGe detector in the low-energy range using empirical and Monte Carlo simulation approaches

The efficiencies of a broad energy germanium detector were characterized down to energies below 10 keV. The K shell X-ray absorption in germanium was seen as a sharp drop in efficiency around 11 keV. This feature was used to determine the thickness of this detector’s dead layer. By comparing efficiency simulations with different dead layer thicknesses to those determined from empirical measurements, the best fit dead layer thickness was determined to be 5.7 ± 1.5 µm. Additional measurements, taken with a collimator, made analytical calculations of the efficiency possible and these results also supported the dead layer thickness determination.