Double-beta decay investigation with highly pure enriched $$^{82}$$ 82 Se for the LUCIFER experiment

Abstract

The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of Se. The matrix which embeds the source is an array of ZnSe crystals, where enriched Se is used as decay isotope. The radiopurity of the initial components employed for manufacturing crystals, that can be operated as bolometers, is crucial for achieving a null background level in the region of interest for double-beta decay investigations. In this work, we evaluated the radioactive content in 2.5 kg of 96.3 % enriched Se metal, measured with a high-purity germanium detector at the Gran Sasso deep underground laboratory. The limits on internal contaminations of primordial decay chain elements of Th, U and U are respectively: 61, 110 and 74 Bq/kg at 90 % C.L. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the Se allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of Se to 0, 2 and 2 excited states of Kr of 3.410, 1.310 and 1.010 y, respectively, with a 90 % C.L.

Low background techniques in bolometers for double-beta decay search

“…For the production of 82 Se-enriched crystals, 15 kg of selenium has been enriched in 82 Se to about 96%. 96 The Zn 82 Se crystal growth has been performed by the Bridgman method from the powder synthesized from zinc and enriched selenium both purified by vacuum distillation. 97 Due to the complexity of the growth process, the Zn 82 Se ingots were grown by single crystallization.…”

Background model of the CUPID-0 experiment

“…The shielding infrastructure is identical to the CUORE-0 one, with the only difference that the 10 mK thermal shield has not been installed, and that the masses of 50 mK and 600 mK shields have been reduced via electrical discharge machining (EDM). The radio-purity of materials used in CUPID-0 experimental setup has been measured with different techniques [8,9,10,11,12], obtaining the results reported in Tab. 1.…”

Extracting Majorana properties from strong bounds on neutrinoless double beta decay

“…There are plans to use 76 be used ever yet but has already been chosen by LUCIFER [32] and SuperNEMO [33].…”