title: Double-beta decay investigation with highly pure enriched [Formula: see text]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 [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.
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA.
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authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, 00185 Rome, Italy.|INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, 00185 Rome, Italy.|INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: INFN, Sezione di Genova, 16146 Genoa, Italy.|Dipartimento di Fisica, Università di Genova, 16126 Genoa, Italy.
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authors.initials: SD
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authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, 00185 Rome, Italy.|INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: Dipartimento di Fisica, Università di Milano-Bicocca, 20126 Milan, Italy.|INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
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authors.affiliation: Centre de Spectrometrié de Masse, 91405 Orsay, France.
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authors.affiliation: INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
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authors.affiliation: INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (L'Aquila), Italy.
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authors.affiliation: Dipartimento di Fisica, Università di Milano-Bicocca, 20126 Milan, Italy.|INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
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authors.affiliation: Gran Sasso Science Institute, 67100 L'Aquila, Italy.
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authors.lastname: Nagorny
authors.affiliation: INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (L'Aquila), Italy.
authors.forename: S
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authors.lastname: Nisi
authors.affiliation: CEA, Irfu, SPP Centre de Saclay, 91191 Gif-sur-Yvette, France.
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authors.affiliation: INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: Gran Sasso Science Institute, 67100 L'Aquila, Italy.
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authors.affiliation: INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (L'Aquila), Italy.
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authors.affiliation: INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
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authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, 00185 Rome, Italy.|INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (L'Aquila), Italy.
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authors.affiliation: INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
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authors.affiliation: INFN, Sezione di Milano Bicocca, 20126 Milan, Italy.
authors.forename: C
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authors.affiliation: INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (L'Aquila), Italy.
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authors.affiliation: INFN, Sezione di Roma, 00185 Rome, Italy.
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authors.affiliation: INFN, Sezione di Roma, 00185 Rome, Italy.
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