Description
CUORE (Cryogenic Underground Observatory for Rare Events) is a tonne-scale experiment located at the LNGS, collecting data since 2017. The main scientific goal is the search for neutrinoless double beta decay in $^{130}$Te. The detector is made of TeO$_2$ crystals operated as cryogenic calorimeters. The use of tellurium with natural isotopic composition allows us to search for rare decays in other isotopes. The neutrinoless positron emitting electron capture ($0\nu EC \beta^+$) of $^{120}$Te (natural abundance 0.09(1)%) has a clear signature from the 511 keV annihilation $\gamma$ rays. We present a coincidence based analysis of this process on a total TeO$_2$ exposure of 355.7 kg $\cdot$ yr, corresponding to 0.2405 kg $\cdot$ yr of $^{120}$Te. We perform a simultaneous spectral fit over five selected decay signatures. We describe the background structure modeling, the limit setting sensitivity and present the unblinded fit results. We find no evidence of $0\nu EC \beta^+$ and set a 90% Bayesian C.I. limit on the half-life of $^{120}$Te for such decay. This result improves by a factor of 10 the existing limit from the combined analysis of CUORE-0 and Cuoricino.
| Collaboration | CUORE |
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