15th International Conference on Topics in Astroparticle and Underground Physics, TAUP2017

Progress toward a two-neutrino double-beta decay measurement for the MAJORANA DEMONSTRATOR

Not scheduled

15m

Alumni Hall

Poster Neutrinos Poster Session

Speaker

Thomas Gilliss (University of North Carolina at Chapel Hill)

Description

The MAJORANA DEMONSTRATOR is a ${}^{76}$Ge-based neutrinoless double-beta decay ($0\nu \beta \beta$) experiment. Staged at the 4850’ level of the Sanford Underground Research Facility, the DEMONSTRATOR operates an array of high-purity p-type point contact Ge detectors deployed within a graded passive shield and an active muon veto system. The present work concerns the two-neutrino double-beta decay mode ($2\nu \beta \beta$) of ${}^{76}$Ge. For Ge detectors, with superior energy resolution (0.1%), this mode poses negligible background to the $0\nu \beta \beta$ mode, even for a ton-scale experiment. However, a precision measurement of the $2\nu \beta \beta$ shape allows for searches for new physics such as Majoron-accompanied $0\nu \beta \beta$. The measurement of the $2\nu \beta \beta$ mode also allows for careful systematic checks of pulse shape discrimination cuts related to both the $0\nu \beta \beta$ and $2\nu \beta \beta$ decay modes. Work is underway to construct a full experimental background model enabling a Bayesian fit to the measured energy spectrum and extraction of a precise $2\nu \beta \beta$ spectrum and half-life determination.