First Search for Neutrinoless Double Beta Decay in 76Ge with the Majorana Demonstrator


Neutrinoless double-beta decay (0νββ) is a hypothetical
lepton-number violating process that would establish the Majorana
nature of neutrinos and serve as an indirect probe of the absolute
neutrino mass. The Majorana Demonstrator is an array of high purity
Ge detectors at the 4850’ level of the Sanford Underground Research
Facility in South Dakota searching for 0νββ in 76 Ge. The experiment
consists of two modules totaling 44 kg of p-type point contact
detectors; the first module began data taking in June 2015, with the
entire array operational since August 2016. I will report the analysis
of the first 9.95 kg*yr of exposure from the MAJORANA
DEMONSTRATOR, achieving a half-life limit of >1.9×10 25 yr for 0νββ
decay of 76 Ge. The experiment has also demonstrated the best
energy resolution and a background consistent with the best
achieved of any 0νββ experiment. These results strongly position
76 Ge for a future tonne-scale 0νββ experiment.

Speaker : 

Walter Pettus, PhD (University of Washington)


Presentation at 3:45 PM, NPL 178 Coffee and cookies starting at 3:30 PM