Speaker
Description
If observed, the theoretical process of neutrinoless double-beta decay (0vBB) would offer insights into the nature of the neutrino, as well as demonstrate that lepton number is not conserved. The Large Enriched Germanium Experiment for Neutrinoless double-beta Decay (LEGEND) utilizes a phased approach to ultimately achieve a total mass of one ton of High Purity Germanium (HPGE) detectors enriched to >90% in $^{76}Ge$ to search for $0\nu\beta\beta$. The current phase of the experiment, L-200, recently published the results of the first science run.
A powerful method used by LEGEND to reject background events that could potentially mimic or obscure a for $0\nu\beta\beta$ signal is pulse shape discrimination (PSD). The efficiencies of these PSD parameters demonstrate an energy dependence, which must be accounted for. To address this, calibration runs using a $^{228}Th$ source are conducted weekly. However, the double escape peak (DEP) used to tune the PSD cuts is at a lower energy than that of the expected $0\nu\beta\beta$ signal. To correct for this, a special $^{56}Co$ run was taken and six DEPS from the $^{56}Co$ spectrum were used to determine the energy dependence of the PSD parameters. This work covers both the PSD cut strategy developed in the LEGEND-200 analysis of the first physics data run, as well a secondary analysis with different cut configurations.
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.