Speaker
Description
Neutrinoless double electron capture (0$\nu$2EC) is a lepton-number-violating process that probes the Majorana nature of neutrinos and provides a complementary approach to neutrinoless double beta decay (0$\nu\beta\beta$) searches. The AMoRE experiment employs scintillating molybdate crystals operated at cryogenic temperatures to investigate rare nuclear processes in a low-background environment.
We report a search for 0$\nu$2EC decay of $^{40}$Ca using data collected with the AMoRE-I calcium molybdate ($^{48\mathrm{dep.}}$Ca$^{100}$MoO$_4$) detector array. Benefitting from high energy resolution and low background conditions, detailed analysis around the Q-value of 193.5 keV is performed. No statistically significant excess consistent with a 0$\nu$2EC is observed. Based on a total exposure of 7.35 kg⋅yr, corresponding to 1.40 kg⋅yr of the $^{40}$Ca isotope, we establish a new world-best limit on the half-life of $1.7\times10^{22}$ yr at 90% confidence level.
We also present the projected sensitivity for the next-generation AMoRE-II experiment, which will significantly improve the discovery potential for 0$\nu$2EC in $^{40}$Ca.