A background model for the {\sc{Majo\-ra\-na}} neutrinoless double-beta decay experiment

The {\sc{Majorana}} Collaboration\footnote{F.T. Avignone III (2007) arXiv:0711.4808v1} will search for neutrinoless double-beta decay ($0\nu\beta\beta$) of $^{76}$Ge in an array of germanium detectors. Observation of $0\nu\beta\beta$ would determine whether the neutrino is a Majorana particle and could provide information about neutrino mass. {\sc{Majorana}} will require an extremely low background rate to acheive high sensitivity to the $0\nu\beta\beta$ rate. Radioactive decays and cosmogenically-induced radiation create backgrounds to the potential signal. Understanding and minimization of backgrounds is critical to the sensitivity of the experiment. The {\sc{Majorana}} background model uses material radiopurity information and Monte Carlo simulation results to describe the expected background energy spectrum. This model can be validated through comparison with low-background energy spectra collected from prototype detectors. {\sc{Majorana}} collaborators installed a low-background germanium detector in the Kimbalton Underground Research Facility (KURF) in Ripplemeade, Virginia. Results of the {\sc{Majorana}} Low-background BEGe at KURF (MALBEK) validation study are used to inform the {\sc{Majorana}} background model.