Speaker
Description
Studies of double beta (2𝜈𝛽𝛽) decay to various excited states in different isotopes provide valuable insights into nuclear structure models. The AMoRE, which utilizes an array of $^{100}$Mo-enriched CaMoO$_{4}$ and Li$_{2}$MoO$_{4}$ crystal scintillators, is advantageous for investigating 2𝜈𝛽𝛽 decay of $^{100}$Mo to the excited states of $^{100}$Ru.
In the AMoRE-I phase, we measured the half-life of 2𝜈𝛽𝛽 transition of $^{100}$Mo to the 0$^+_1$ state of $^{100}$Ru using in total 18 crystal detectors, and the half-life value is (6.83 ± 0.71 (stat) ± 0.32 (sys)) × 10$^{20}$ years. The half-life limit for the 2𝜈𝛽𝛽 transition to the 2$^+_1$ state of $^{100}$Ru is set as 2.5 × 10$^{21}$ years (90% C.I.).
A prospective study of 2𝜈𝛽𝛽 decay to the excited states of $^{100}$Ru has been conducted for AMoRE-II. Considering the increased crystal mass and measurement time, the error-to-signal ratio for the 2𝜈𝛽𝛽 decay of $^{100}$Mo to the 0$^+_1$ state is expected to decrease significantly from 6.3% to 0.3%. The half-life sensitivity to the 2𝜈𝛽𝛽 decay of $^{100}$Mo to 2$^+_1$ state of $^{100}$Ru in AMoRE-II is estimated as limit T$_{1/2}$ ~ 1.20 × 10$^{23}$ years. And the triple-crystal-hit conditions event can be measured in AMoRE-II, that will be useful for observing the pure election energy distribution.
