Results on ${}^{82}$Se $2\nu \beta \beta$ with CUPID-0 Phase I

Abstract

The nucleus is an extraordinarily complex object where fundamental forces are at work. The solution of this many-body problem has challenged physicists for decades: several models with complementary virtues and flaws have been adopted, none of which has a universal predictive capability. Double beta decay is a second-order weak nuclear decay whose precise measurement might steer fundamental improvements in nuclear theory. Its knowledge paves the way to a much better understanding of many-body nuclear dynamics and clarifies, in particular, the role of multiparticle states. This is a useful input to a complete understanding of the dynamics of neutrino-less double beta decay, the chief physical process whose discovery may shed light to the matter-antimatter asymmetry of the universe and unveil the true nature of neutrinos. Here, we report the study of $2\nu \beta \beta$-decay in ${}^{82}$Se with the CUPID-0 detector, an array of ZnSe crystals maintained at a temperature close to 'absolute zero' in an ultralow background environment. Thanks to the unprecedented accuracy in the measurement of the two electrons spectrum, we prove that the decay is dominated by a single intermediate state. We obtain also the most precise value for the ${}^{82}$Se $2\nu \beta \beta$-decay half-life of $T_{1/2}^{2\nu }=[8.6_{-0.1}^{+0.2}]\times 10^{19}$ yr.

References in corpus (9)

• Phase space factors for double-$\beta$ decay
• Nuclear matrix elements for double-β decay
• Value of the axial-vector coupling strength in $\beta$ and $\beta \beta$ decays: A review
• Average and recommended half-life values for two neutrino double beta decay
• Measurement of the Two-Neutrino Double Beta Decay Half-life of ${}^{130}$Te with the CUORE-0 Experiment
• Final result of CUPID-0 phase-I in the search for the ${}^{82}$Se Neutrinoless Double Beta Decay
• First Direct Double-Beta Decay Q-value Measurement of 82Se in Support of Understanding the Nature of the Neutrino
• Background Model of the CUPID-0 Experiment
• Single and low-lying states dominance in two-neutrino double-beta decay