NSF Award
1206314
A comprehensive program in neutrino-less double-beta decay is very timely. A principal finding of the APS Multidivisional Study stated: "We recommend, as a high priority, a phased program of sensitive searches for neutrino-less nuclear double-beta decay." The intellectual merit of this award is based on the fact that the observation of such a decay is the only practical way to determine if neutrinos are Majorana particles (their own antiparticles). This exotic decay is the most sensitive test of lepton number conservation, an important symmetry in elementary-particle physics. In fact, if neutrinos are Majorana particles, a measurement of the decay half-life would yield the effective Majorana mass of the electron neutrino. This result, combined with neutrino oscillation data, would determine all three neutrino-mass eigenvalues. Is leptogenesis even a possibility? Yes, but only if neutrinos are Majorana particles. <br/><br/>These funds are awarded to assist the Majorana Demonstrator (MJD) experiment searching for neutrino-less double beta decay in germanium -76 (Ge-76). The specific and limited work is to carry-out the highly technical conversion of germanium oxide (GeO2) into metallic form suitable for the fabrication of Ge detector units. The PI leads the Task in the MJD R&D Project responsible for the procurement of enriched GeO2, its reduction to metal, zone refinement to detector quality Ge metal, and reprocessing of the scrap material. The PIs formed the team that equipped the facility and acquired the necessary equipment for the Ge processing and reprocessing; they are now operating the facility. Recently two Russian Institutes have agreed to loan MJD between 8.7 and 14.5-kg of enriched GeO2. The cost of processing this material was not covered in the original proposal. Accordingly, this funding is provided for the reduction, zone refinement and reprocessing of this material, and for new R&D to develop more efficient scrap reprocessing. This new loaned GeO2 will significantly extend the science reach of the MJD.<br/><br/>Broader impacts: <br/>One broader impact would be an important contribution to cosmology. Another is, and has been, new detector technology for National and Homeland security. A third broader impact is new ultra-low background Ge-detector technology for other basic and applied sciences. In fact, this technology has broad application in environmental radiological surveys.
