Background Model Fitting for the MAJORANA DEMONSTRATOR

The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay experiment consisting of two modules containing p-type point contact germanium detectors surrounded by a graded shield and located at the 4850' level of the Sanford Underground Research Facility. The experiment has a leading energy resolution of 2.5 keV FWHM as well as one of the lowest backgrounds in the region of interest surrounding the double-beta decay Q-value. Background model fits to data from the DEMONSTRATOR aim to determine the sources of observed backgrounds, explain deviations between the measured background rate and assay-based predictions, and make a precision measurement of the two-neutrino double-beta decay half-life. In this talk, we present recent progress in background modeling aimed at addressing the challenges of reliably fitting a large group of simulated spectra that represent each module's components to a low background dataset. We also discuss work to quantify systematic errors due to model uncertainties, such as those associated with the dead layer profiles of the detectors.