The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)

Abstract

The observation of neutrinoless double-beta decay (0$\hat{I}½{\hat{I}}^2{\hat{I}}^2$) would show that lepton number is violated, reveal that neutrinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of $\sim$0.1 count /(FWHM$\cdot$t$\cdot$yr) in the region of the signal. The current generation ${}^{76}$Ge experiments GERDA and the MAJORANA DEMONSTRATOR utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0$\hat{I}½{\hat{I}}^2{\hat{I}}^2$ signal region of all 0$\hat{I}½{\hat{I}}^2{\hat{I}}^2$ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale ${}^{76}$Ge experiment. The collaboration aims to develop a phased 0$\hat{I}½{\hat{I}}^2{\hat{I}}^2$ experimental program with discovery potential at a half-life approaching or at $10^{28}$ years, using existing resources as appropriate to expedite physics results.

Proceedings of the MEDEX'17 meeting (Prague, May 29 - June 2, 2017)