- Beeman, JW
- Bellini, F
- Benetti, P
- Cardani, L
- Casali, N
- Chiesa, D
- Clemenza, M
- Dafinei, I
- Domizio, S Di
- Ferroni, F
- Gironi, L
- Giuliani, A
- Gotti, C
- Laubenstein, M
- Maino, M
- Nagorny, S
- Nisi, S
- Nones, C
- Orio, F
- Pagnanini, L
- Pattavina, L
- Pessina, G
- Piperno, G
- Pirro, S
- Previtali, E
- Rusconi, C
- Schäffner, K
- Tomei, C
- Vignati, M
- et al.

The LUCIFER project aims at deploying the first array of enriched scintillating bolometers for the investigation of neutrinoless double-beta decay of [Formula: see text]Se. The matrix which embeds the source is an array of ZnSe crystals, where enriched [Formula: see text]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 [Formula: see text]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 [Formula: see text]Th, [Formula: see text]U and [Formula: see text]U are respectively: [Formula: see text]61, [Formula: see text]110 and [Formula: see text]74 [Formula: see text]Bq/kg at 90 % C.L. The extremely low-background conditions in which the measurement was carried out and the high radiopurity of the [Formula: see text]Se allowed us to establish the most stringent lower limits on the half-lives of the double-beta decay of [Formula: see text]Se to 0[Formula: see text], 2[Formula: see text] and 2[Formula: see text] excited states of [Formula: see text]Kr of 3.4[Formula: see text]10[Formula: see text], 1.3[Formula: see text]10[Formula: see text] and 1.0[Formula: see text]10[Formula: see text] y, respectively, with a 90 % C.L.