Speaker
Description
LEGEND (Large Enriched Germanium Experiment for Neutrinoless ββ-Decay) is searching for neutrinoless double-beta decay (0νββ), a hypothetical rare nuclear process that would, if discovered, prove that the neutrino is a Majorana particle, provide the first observation of Lepton number violation, and may help explain the excess of matter over anti-matter in the universe. To perform this search, LEGEND is using an array of high-purity germanium detectors isotopically enriched in $^{76}$Ge, which act as both source and detector of 0νββ.
LEGEND aims for an half-life sensitivity to 0νββ of $10^{28}$ y, which will require a quasi-background-free observation with a large exposure (~10 ton-y). To minimize backgrounds, LEGEND is pursuing multiple complementary strategies, including the use of clean materials, deployment in liquid argon that acts as an active shield, and the use of point-contact detectors with excellent energy resolution and background-discrimination capabilities.
LEGEND is pursuing a phased deployment strategy. LEGEND-200 is currently operating with an planned deployment of 200 kg of detectors and a half-life sensitivity goal of $10^{27}$ y. LEGEND-1000 will deploy 1000 kg of detectors with a half-life sensitivity goal of $10^{28}$ y. LEGEND-200 has produced its first quasi-background-free limit on the half-life of 0νββ in $^{76}$Ge using 61.0 kg-y of data. A median half-life sensitivity at 90% C.L. of 2.8×$10^{26}$ y was achieved, combining data from LEGEND, GERDA, and the MAJORANA DEMONSTRATOR. This poster will provide an overview of this limit, and projections of the sensitivity of LEGEND-200 and LEGEND-1000 based on our current understanding of backgrounds.
This work is supported by the U.S. DOE, and the NSF, the LANL, ORNL and LBNL LDRD programs; the European ERC and Horizon programs; the German DFG, BMBF, and MPG; the Italian INFN; the Polish NCN and MNiSW; the Czech MEYS; the Slovak RDA; the Swiss SNF; the UK STFC; the Canadian NSERC and CFI; the LNGS and SURF facilities.