An ultra-low-level gamma-ray counting setup was commissioned at the Felsenkeller shallow-underground laboratory, located at a depth of 140 m.w.e., in Dresden, Germany. This setup features a high-purity germanium (HPGe) detector with 163% relative efficiency, enclosed within both passive and active shielding. These shielding types reduce the remaining background rate to 116(1) counts kg−1d−1 within the energy range [40 keV, 2700 keV], making it the most sensitive HPGe detector in Germany and enabling the investigation of samples with activities well below 1 mBq.

In addition to describing the setup design, this contribution will present the Monte Carlo simulation of the detector. A current application of this work is the measurement of a rare meteorite sample, where 3D scanning techniques and simulations were used to determine the specific activities of cosmogenic radionuclides.