First results from the AMoRE-Pilot neutrinoless double beta decay experiment

The advanced molybdenum-based rare process experiment (AMoRE) aims to search for neutrinoless double beta decay (0νββ) of100Mo with ∼ 100kg of 100Moenrichedmolybdenumembeddedincryogenicdetectorswith adualheatandlightreadout.Atthecurrent,pilotstageofthe AMoRE project we employ six calcium molybdate crystals withatotalmassof1.9kg,producedfrom48Ca-depletedcalcium and 100Mo-enriched molybdenum (48deplCa100MoO4). The simultaneous detection of heat (phonon) and scintillation (photon) signals is realized with high resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin temperatures. This stage of the project is carried out in the Yangyang underground laboratory at a depth of 700 m. We report first results from the AMoRE-Pilot 0νββ search with a 111 kg day live exposure of 48deplCa100MoO4 crystals. No evidence for 0νββ decay of 100Mo is found, and a upper limit is set for the half-life of 0νββ of 100Mo of T0ν 1/2 > 9.5×1022 years at 90% C.L. This limit corresponds to an effective Majorana neutrino mass limit in the range mββ≤(1.2−2.1)eV. © The Author(s) 201911sciescopu