Complete event-by-event α/γ(β) separation in a full-size TeO2 CUORE bolometer by Neganov-Luke-magnified light detection

L. Bergé, M. Chapellier, M. De Combarieu, L. Dumoulin, A. Giuliani, M. Gros, P. De Marcillac, S. Marnieros, C. Nones, V. Novati, E. Olivieri, B. Paul, D. V. Poda, T. Redon, B. Siebenborn, A. S. Zolotarova, E. Armengaud, C. Augier, A. Benoît, J. BillardA. Broniatowski, P. Camus, A. Cazes, F. Charlieux, M. De Jesus, K. Eitel, N. Foerster, J. Gascon, Y. Jin, A. Juillard, M. Kleifges, V. Kozlov, H. Kraus, V. A. Kudryavtsev, H. Le Sueur, R. Maisonobe, X. F. Navick, P. Pari, E. Queguiner, S. Rozov, V. Sanglard, L. Vagneron, M. Weber, E. Yakushev

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18 Scopus citations

Abstract

In the present work, we describe the results obtained with a large (≈133cm3) TeO2 bolometer, with a view to a search for neutrinoless double-β decay (0νββ) of Te130. We demonstrate an efficient α-particle discrimination (99.9%) with a high acceptance of the 0νββ signal (about 96%), expected at ≈2.5 MeV. This unprecedented result was possible thanks to the superior performance (10-eV rms baseline noise) of a Neganov-Luke-assisted germanium bolometer used to detect a tiny (70-eV) light signal from the TeO2 detector, dominated by γ(β)-induced Cherenkov radiation but exhibiting also a clear scintillation component. The obtained results represent a major breakthrough toward the TeO2-based version of the CUORE Upgrade with Particle IDentification (CUPID), a ton-scale cryogenic 0νββ experiment proposed as a followup to the Cryogenic Underground Observatory for Rare Events (CUORE) project with particle identification. The CUORE experiment recently began a search for neutrinoless double-β decay of Te130 with an array of 988 125-cm3TeO2 bolometers. The lack of α discrimination in CUORE makes α decays at the detector surface the dominant background component, at the level of ≈0.01 counts/(keV kg y) in the region of interest. We show here, for the first time with a CUORE-size bolometer and using the same technology as CUORE for the readout of both heat and light signals, that surface α background can be fully rejected.

Original languageEnglish (US)
Article number032501
JournalPhysical Review C
Volume97
Issue number3
DOIs
StatePublished - Mar 12 2018

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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