The AMoRE: Search for neutrinoless double beta decay of ¹⁰⁰Mo

The AMoRE (Advanced Mo-based Rare process Experiment) collaboration is using calcium molybdate (^dep48Ca ¹⁰⁰MoO₄) crystals enriched in ¹⁰⁰Mo and depleted in ⁴⁸Ca to search for neutrinoless double-beta decay (DBD) of ¹⁰⁰Mo using at the underground laboratory in Korea. Metallic magnetic calorimeters operating a milliKelvin temperatures are used as temperature sensors to measure heat and light signals from the crystals. The simultaneous and fast detection capabilities for both phonons and photons, and their excellent energy resolution provide powerful methods for identifying DBD signals and rejecting background events, which are mainly due to random coincidences between two uncorrelated two-neutrino-double-beta decays of ¹⁰⁰Mo. The AMoRE-Pilot experiment that is currently underway uses a 1.5 kg, five-element array of ^dep48Ca ¹⁰⁰MoO₄ crystals. The ultimate goal is a ∼200 kg array of crystals and a half-life sensitivity of order 10²⁶ years, which will access the inverted hierarchy region for effective Majorana neutrino masses, i.e., 0.02 to 0.05 eV. In this talk, we present recent progress on the development of low-background calcium molybdate detectors and results from room- and milli-Kelvin temperatures. Sensitivities based on GEANT4 simulations that incorporate measured background are reported.