UC Berkeley

CUORICINO was a cryogenic bolometer experiment designed to search for neutrinoless

double beta decay and other rare processes, including double beta decay with two neutrinos

(2νββ). The experiment was located at Laboratori Nazionali del Gran Sasso and ran for a period of about 5 years, from 2003 to 2008. The detector consisted of an array of 62 TeO₂ crystals arranged in a tower and operated at a temperature of ∼10 mK. Events depositing energy in the detectors, such as radioactive decays or impinging particles, produced thermal pulses in the crystals which were read out using sensitive thermistors.

The experiment included 4 enriched crystals, 2 enriched with ¹³⁰Te and 2 with ¹²⁸Te, in order to aid in the measurement of the 2νββ rate. The enriched crystals contained a total of ∼350 g ¹³⁰Te. The 128-enriched (130-depleted) crystals were used as background monitors, so that the shared backgrounds could be subtracted from the energy spectrum of the 130-enriched crystals. Residual backgrounds in the subtracted spectrum were fit using spectra generated by Monte-Carlo simulations of natural radioactive contaminants located in and on the crystals. The 2νββ half-life was measured to be T_1/2 = [9.81 ± 0.96(stat) ± 0.49(syst)]×

10²⁰ y.