Activity Calculations using HPGe Detectors and Monte Carlo Efficiencies

The next generation of experiments in particle astrophysics will require extremely low and well-known backgrounds. This requires performing experiments with low activity materials and going underground to escape the ubiquitous cosmic-ray background. Current radiometric assays using low background HPGe detectors at the recently established Kimballton Underground Research Facility for Low Background Counting (KURF LBC ) examine the bulk activity of materials that will be used in direct dark matter searches such as Mini-CLEAN and in the search for 0$\nu$$\beta$$\beta$ by the MAJORANA Collaboration. Finding the bulk activity from the spectra of a measured sample is involved. To account for branching ratios, geometry effects, and attenuation in the sample and non-active parts of the detector-- Monte Carlo calculations of peak acceptances were made using the MaGe/GEANT4 simulation package in addition to modeling the affect of energy resolution on peak height to continuum ratio from fitted data.