Progress in Background Model Fitting for the MAJORANA DEMONSTRATOR

The MAJORANA DEMONSTRATOR is a neutrinoless double-beta decay experiment consisting of two modules containing ~30kg of p-type point contact germanium detectors enriched to 88% in 76Ge and ~14kg of natural germanium detectors. These modules are surrounded by a graded shield and located at the 4850' level of the Sanford Underground Research Facility. The DEMONSTRATOR has achieved one of the lowest background rates in the region of the 0?????? Q-value. In addition, extremely low backgrounds in the energy region below 100 keV have enabled searches for other beyond the standard model processes. Background model fits using two different statistical approaches aim to determine the sources of observed backgrounds, explain deviations from assay-based projections, and allow a precision measurement of the two-neutrino double-beta decay half-life. In this talk, we present recent progress in background modeling including improved fits to a significant portion of the experiment's full exposure and efforts to quantify systematic errors due to model uncertainties.