Majorana Collaboration Passes DOE/NSF Critical Design Review

On May 23, 2012 the Majorana Collaboration, led by John Wilkerson from UNC, successfully passed the DOE/NSF review of the Majorana Demonstrator project. This project is a zero-neutrino double-beta decay search using a combination of up to 40 kg of natural and enriched (in 76Ge) High-Purity Germanium (HPGe) detectors. It is funded at the $22M plus level by DOE and the NSF. The Majorana project was conceived in 1999 by Profs. Ludwig DeBraeckeleer and Werner Tornow from Duke, Frank Avignone from the University of South Carolina, and Harry Miley from Pacific Northwest National Laboratory. In the following years Profs.  Avignone and Tornow successfully increased the size and stature of the collaboration for this ambitious project. Currently, the Majorana Collaboration consists of about 90 researchers from 19 institutions in 4 countries. The project management is located at Oak Ridge National Laboratory, one of five U.S. national laboratories involved in the Majorana Demonstrator project. After passing the Critical Design Review 2/3, the Majorana Collaboration will now proceed with the installation of its test cryostat filled with 7 natural HPGe detectors at the Homestake mine in Lead, SD. The cryostats #1 and #2 are scheduled to be installed in the years 2013 and 2014, respectively, using predominately enriched HPGe detectors. The main purpose of the Majorana Demonstrator is to show that a 1 tonne experiment using enriched HPGe detectors can be built with a background as low as 1 count per tonne-year in the energy region of interest for zero-neutrino double-beta decay (2039 keV). Such a large scale experiment is needed to probe the neutrino mass region down to the 20 meV level after 10 years of counting. After two years of data taking with the Majorana Demonstrator, the collaboration will confirm or refute the claim that the zero-neutrino double-beta decay of 76Ge has been observed [H.V. Klapdor et al., Modern Physics Lett. A 16, 2409 (2001)].