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

TL;DR

The LEGEND experiment aims to detect neutrinoless double-beta decay using high-purity germanium detectors, striving for extremely low background levels and high energy resolution to explore neutrino properties and mass scale.

Contribution

LEGEND introduces a phased, tonne-scale germanium experiment building on previous successes to achieve unprecedented sensitivity in neutrinoless double-beta decay detection.

Findings

Achieved lowest backgrounds among 0νββ experiments

Developing phased approach for increased sensitivity

Targeting half-life sensitivity of 10^28 years

Abstract

The observation of neutrinoless double-beta decay (0${\nu}{\beta}{\beta}$) 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${\nu}{\beta}{\beta}$ signal region of all 0${\nu}{\beta}{\beta}$ 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${\nu}{\beta}{\beta}$ experimental program with discovery potential at a half-life approaching or at $10^{28}$ years, using existing resources as appropriate to expedite physics results.