The MAJORANA Project

Abstract

Building a \\BBz experiment with the ability to probe neutrino mass in the\ninverted hierarchy region requires the combination of a large detector mass\nsensitive to \\BBz, on the order of 1-tonne, and unprecedented background\nlevels, on the order of or less than 1 count per year in the \\BBz signal\nregion. The MAJORANA Collaboration proposes a design based on using high-purity\nenriched Ge-76 crystals deployed in ultra-low background electroformed Cu\ncryostats and using modern analysis techniques that should be capable of\nreaching the required sensitivity while also being scalable to a 1-tonne size.\nTo demonstrate feasibility, the collaboration plans to construct a prototype\nsystem, the MAJORANA DEMONSTRATOR, consisting of 30 kg of 86% enriched \\Ge-76\ndetectors and 30 kg of natural or isotope-76-depleted Ge detectors. We plan to\ndeploy and evaluate two different Ge detector technologies, one based on a\np-type configuration and the other on n-type.\n