Background Reduction in the Majorana Neutrinoless Double-Beta Decay Experiment.

Majorana is a proposed, scalable, 180-kg array of enriched germanium crystals that will search for neutrinoless double-beta (0\textit{$\nu \beta \beta $}) decay in $^{76}$Ge. The focus of this talk is the reduction of backgrounds in Majorana, a vital aspect of any low-background experiment. The first step is identification of possible backgrounds, including radioactive contamination in the detector and cosmic-ray induced backgrounds. The next step is estimating background reduction from mitigating techniques, including ultra-pure material manufacturing, shielding, detector granularity, crystal segmentation, pulse-shape analysis, time correlations, and underground manufacturing and operation. Finally, all these components are assembled into a background model. With this background model, we are confident we can improve the current half-life limit of 0\textit{$\nu \beta \beta $} decay in $^{76}$Ge from 2 x 10$^{25}$ years to about 5.5 x 10$^{26}$ years, in the absence of a 0\textit{$\nu \beta \beta $} decay signal.