Determination of Mo- and Ca-isotope ratios in Ca~(100)MoO_4 crystal for AMoRE-I experiment

摘要

The first phase of the AMoRE (Advanced Mo-based Rare process Experiment) is to search for neutrinoless double-beta decay of ~(100)Mo with calcium molybdate (Ca~(100)MoO_4) crystals enriched in ~(100)Mo and depleted in ~(48)Ca using a cryogenic technique at Yangyang underground laboratory in Korea. It is important to know ~(100)Mo- and ~(48)Ca-isotope ratios in Ca~(100)MoO_4 crystal to estimate half-life of ~(100)Mo decays and to 2vββ background from ~(48)Ca. We employed the ICP-MS (Inductive Coupled Plasma Mass Spectrometer) to measure ~(100)Mo- and ~(48)Ca-isotope ratios in Ca~(100)MoO_4 crystal. The measured results for ~(100)Mo- and ~(48)Ca-isotope ratios in the crystal are (94.6±2.8)% and (0.00211 ±0.00006)%, respectively, where errors are included both statistical and systematic uncertainties.