Precise efficiency calibration of an HPGe detector: source measurements and Monte Carlo calculations with sub-percent precision

With the goal of measuring precise gamma-ray intensities for short-lived (<5 s) accelerator-produced activities, we have calibrated the efficiency of an HPGe detector between 53 and 1836 keV to sub-percent precision with a combination of source measurements and Monte Carlo calculations. Using known or independently measured detector dimensions, we have achieved both relative and absolute agreement (the latter, to 0.1%) between the calculated and measured efficiencies with only two adjustable detector parameters, the thicknesses of the contact dead layers.