Search for neutrinoless double beta decay of $^{64}$Zn and $^{70}$Zn with CUPID-0
Résumé
CUPID-0 is the first pilot experiment of CUPID, a next-generation project searching for neutrinoless double beta decay. In its first scientific run, CUPID-0 operated 26 ZnSe cryogenic calorimeters coupled to light detectors in the underground Laboratori Nazionali del Gran Sasso. In this work, we analyzed a ZnSe exposure of 11.34 kg year to search for the neutrinoless double beta decay of $^{70}$Zn and for the neutrinoless positron-emitting electron capture of $^{64}$Zn. We found no evidence for these decays and set 90$\%$ credible interval limits of $\hbox {T}_{1/2}^{0\nu \beta \beta }$($^{70}$Zn) > 1.6 $10^{21}$ year and $\hbox {T}_{1/2}^{0\nu EC \beta +}$($^{64}$Zn) > 1.2$\times 10^{22}$ year, surpassing by more than one order of magnitude the previous experimental results (Belli et al. in J Phys G 38(11):115107, https://doi.org/10.1088/0954-3899/38/11/115107, 2011).