A New Limit on the Neutrinoless DBD of 130Te

TL;DR

This paper reports on CUORICINO, a cryogenic experiment that sets a new lower limit on the half-life of neutrinoless double beta decay of 130Te, constraining neutrino mass models.

Contribution

It provides the first experimental lower limit on the neutrinoless double beta decay half-life of 130Te using a large cryogenic detector array.

Findings

No evidence of neutrinoless DBD detected

Established a 90% C.L. lower limit of 1.8×10^24 years for the decay half-life

Set an upper bound on the effective neutrino mass from 0.2 to 1.1 eV

Abstract

We report the present results of CUORICINO a cryogenic experiment on neutrinoless double beta decay (DBD) of 130Te consisting of an array of 62 crystals of TeO2 with a total active mass of 40.7 kg. The array is framed inside of a dilution refrigerator, heavily shielded against environmental radioactivity and high-energy neutrons, and operated at a temperature of ~8 mK in the Gran Sasso Underground Laboratory. Temperature pulses induced by particle interacting in the crystals are recorded and measured by means of Neutron Transmutation Doped thermistors. The gain of each bolometer is stabilized with voltage pulses developed by a high stability pulse generator across heater resistors put in thermal contact with the absorber. The calibration is performed by means of two thoriated wires routinely inserted in the set-up. No evidence for a peak indicating neutrinoless DBD of 130Te is detected and a 90% C.L. lower limit of 1.8E24 years is set for the lifetime of this process. Taking largely into account the uncertainties in the theoretical values of nuclear matrix elements, this implies an upper boud on the effective mass of the electron neutrino ranging from 0.2 to 1.1 eV. This sensitivity is similar to those of the 76Ge experiments.