Search for double-beta decay of $$\mathrm {^{130}Te}$$ 130 Te to the $$0^+$$ 0 + states of $$\mathrm {^{130}Xe}$$ 130 Xe with CUORE

Abstract

Abstract The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay (

$$0\nu \beta \beta $$

0 ν β β

) in the isotope

$$\mathrm {^{130}Te}$$

130

Te

. In this work we present the latest results on two searches for the double beta decay (DBD) of

$$\mathrm {^{130}Te}$$

130

Te

to the first

$$0^{+}_2$$

0 2 +

excited state of

$$\mathrm {^{130}Xe}$$

130

Xe

: the

$$0\nu \beta \beta $$

0 ν β β

decay and the Standard Model-allowed two-neutrinos double beta decay (

$$2\nu \beta \beta $$

2 ν β β

). Both searches are based on a 372.5 kg

$$\times $$

×

yr TeO

$$_2$$

2

exposure. The de-excitation gamma rays emitted by the excited Xe nucleus in the final state yield a unique signature, which can be searched for with low background by studying coincident events in two or more bolometers. The closely packed arrangement of the CUORE crystals constitutes a significant advantage in this regard. The median limit setting sensitivities at 90% Credible Interval (C.I.) of the given searches were estimated as

$$\mathrm {S^{0\nu }_{1/2} = 5.6 \times 10^{24} \, \mathrm {yr}}$$

S

1 / 2

0 ν

= 5.6 ×

10 24

yr

for the

$${0\nu \beta \beta }$$

0 ν β β

decay and

$$\mathrm {S^{2\nu }_{1/2} = 2.1 \times 10^{24} \, \mathrm {yr}}$$

S

1 / 2

2 ν

= 2.1 ×

10 24

yr

for the

$${2\nu \beta \beta }$$

2 ν β β

decay. No significant evidence for either of the decay modes was observed and a Bayesian lower bound at

$$90\%$$

90 %

C.I. on the decay half lives is obtained as:

$$\mathrm {(T_{1/2})^{0\nu }_{0^+_2} > 5.9 \times 10^{24} \, \mathrm {yr}}$$

(

T

1 / 2

)

0 2 +

0 ν

> 5.9 ×

10 24

yr

for the

$$0\nu \beta \beta $$

0 ν β β

mode and

$$\mathrm {(T_{1/2})^{2\nu }_{0^+_2} > 1.3 \times 10^{24} \, \mathrm {yr}}$$

(

T

1 / 2

)

0 2 +

2 ν

> 1.3 ×

10 24

yr

for the

$$2\nu \beta \beta $$

2 ν β β

mode. These represent the most stringent limits on the DBD of

$$^{130}$$

130

Te to excited states and improve by a factor

$$\sim 5$$

∼ 5

the previous results on this process.