The Majorana Project: A next-generation double-beta decay experiment

The Majorana Project will endeavor to provide direct limits on the effective Majorana mass of the electron neutrino through the measurement of Ov beta beta decay in Ge-76. Our goal is an experiment with a scalable sensitivity starting at 100 meV (corresponding to the quasi-degenerate mass scale) and ultimately extending well below that level. The current Majorana design consists of several modules, each a close-packed array of 57 Ge detectors, enriched to 86% in Ge-76, in a single cryostat. The ultimate background goal for Majorana is of order one count per tonne of Ge per year in the four keV region of interest around Q(beta beta). This background will allow us to reach an effective Majorana-neutrino mass sensitivity approximately five times better than current results and should cover the quasi-degenerate mass scale.