Complete event-by-event $\alpha/\gamma(\beta)$ separation in a full-size ${\mathrm{TeO}}_{2}$ CUORE bolometer by Neganov-Luke-magnified light detection

L. Bergé (1) , M. Chapellier (1) , M. de Combarieu (2, 3) , L. Dumoulin (1) , A. Giuliani (1) , M. Gros (4) , P. de Marcillac (1) , S. Marnieros (1) , C. Nones (4) , V. Novati (1) , E. Olivieri (1) , B. Paul (4) , D.V. Poda (1) , T. Redon (1) , B. Siebenborn (5) , A.S. Zolotarova (4, 6) , E. Armengaud (4) , C. Augier (7) , A. Benoît (8) , J. Billard (7) , A. Broniatowski (1) , P. Camus (9) , A. Cazes (7) , F. Charlieux (7) , M. de Jesus (7) , K. Eitel (5) , N. Foerster (10) , J. Gascon (7) , Y. Jin (11) , A. Juillard (7) , M. Kleifges (12) , V. Kozlov (10) , H. Kraus (13) , V.A. Kudryavtsev (14) , H. Le Sueur (2, 15) , R. Maisonobe (7) , X-F. Navick (4, 16) , P. Pari (2, 3) , E. Queguiner (7) , S. Rozov (17) , V. Sanglard (7) , L. Vagneron (7) , M. Weber (12) , E. Yakushev (17)

1 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
2 SPEC - UMR3680 - Service de physique de l'état condensé
3 LC - Laboratoire de Cryogénie
4 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
5 EKP - Institut für Experimentelle Kernphysik [Karlsruhe]
6 DPhP - Département de Physique des Particules (ex SPP)
7 IPNL - Institut de Physique Nucléaire de Lyon
8 NEEL - HELFA - Hélium : du fondamental aux applications
9 NEEL - Cryo - Cryogénie
10 KIT - Karlsruhe Institute of Technology
11 C2N - Centre de Nanosciences et de Nanotechnologies [Orsay]
12 IPE - Institut für Prozessdatenverarbeitung und Elektronik
13 Department of Physics [Oxford]
14 Department of Physics and Astronomy [Sheffield]
15 QUANTRONICS - Quantronics Group
16 DEDIP - Département d'Electronique, des Détecteurs et d'Informatique pour la Physique (ex SEDI)
17 DLNP - Dzhelepov Laboratory of Nuclear Problems [Dubna]

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.

Mots clés: double-beta decay: (0neutrino); background: suppression; radiation: Cherenkov; bolometer; CUORE; helium: particle identification; photon: particle identification; electron: particle identification; performance; tellurium: nuclide; tellurium: oxygen; helium: background

Domaines: Instrumentations et Détecteurs [physics.ins-det]; Physique des Hautes Energies - Expérience [hep-ex]

L. Bergé, M. Chapellier, M. de Combarieu, L. Dumoulin, A. Giuliani, et al.. Complete event-by-event $\alpha/\gamma(\beta)$ separation in a full-size ${\mathrm{TeO}}_{2}$ CUORE bolometer by Neganov-Luke-magnified light detection. Physical Review C, 2018, 97 (3), pp.032501. ⟨10.1103/PhysRevC.97.032501⟩. ⟨hal-01737889⟩