Eur. Phys. J. C (2022) 82: 810
https://doi.org/10.1140/epjc/s10052-022-10720-3

Regular Article - Experimental Physics

Optimization of the first CUPID detector module

¹ Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
² University of California, Los Angeles, CA, USA
³ IRFU, CEA, Université Paris-Saclay, Saclay, France
⁴ Univ Lyon, Université Lyon 1, CNRS/IN2P3, IP2I-Lyon, 69622, Villeurbanne, France
⁵ University of South Carolina, Columbia, SC, USA
⁶ INFN Laboratori Nazionali di Legnaro, Legnaro, Italy
⁷ INFN Laboratori Nazionali del Gran Sasso, Assergi, AQ, Italy
⁸ National Research Centre Kurchatov Institute, Institute for Theoretical and Experimental Physics, Moscow, Russia
⁹ INFN Sezione di Bologna, Bologna, Italy
¹⁰ INFN Sezione di Milano-Bicocca, Milan, Italy
¹¹ University of Milano-Bicocca, Milan, Italy
¹² INFN Sezione di Roma, Rome, Italy
¹³ Sapienza University of Rome, Rome, Italy
¹⁴ University of California, Berkeley, CA, USA
¹⁵ CNR-Institute for Microelectronics and Microsystems, Bologna, Italy
¹⁶ INFN Sezione di Genova, Genoa, Italy
¹⁷ University of Genova, Genoa, Italy
¹⁸ Lawrence Berkeley National Laboratory, Berkeley, CA, USA
¹⁹ Gran Sasso Science Institute, L’Aquila, Italy
²⁰ Argonne National Laboratory, Argonne, IL, USA
²¹ CNR-Institute of Nanotechnology, Rome, Italy
²² Yale University, New Haven, CT, USA
²³ INFN Laboratori Nazionali di Frascati, Frascati, Italy
²⁴ Institute for Nuclear Research of NASU, Kyiv, Ukraine
²⁵ Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
²⁶ INFN Sezione di Roma and Sapienza University of Rome, Rome, Italy
²⁷ Northwestern University, Evanston, IL, USA
²⁸ Massachusetts Institute of Technology, Cambridge, MA, USA
²⁹ Fudan University, Shanghai, China
³⁰ Boston University, Boston, MA, USA
³¹ California Polytechnic State University, San Luis Obispo, CA, USA
³² Shanghai Jiao Tong University, Shanghai, China
³³ Drexel University, Philadelphia, PA, USA
³⁴ Johns Hopkins University, Baltimore, MD, USA
³⁵ Beijing Normal University, Beijing, China
³⁶ Centro de Astropartículas y Física de Altas Energías, Universidad de Zaragoza, Zaragoza, Spain
³⁷ ARAID Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain
³⁸ University of Science and Technology of China, Hefei, China
³⁹ Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia
⁴⁰ INFN Sezione di Padova, Padua, Italy
⁴¹ Univ. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France
⁴² University of Bologna, Bologna, Italy

^a cupid.publications@lngs.infn.it

Received: 15 February 2022
Accepted: 18 August 2022
Published online: 12 September 2022

Abstract

CUPID will be a next generation experiment searching for the neutrinoless double $\beta$ decay, whose discovery would establish the Majorana nature of the neutrino. Based on the experience achieved with the CUORE experiment, presently taking data at LNGS, CUPID aims to reach a background free environment by means of scintillating Li${}_2$${}^{100}$MoO${}_4$ crystals coupled to light detectors. Indeed, the simultaneous heat and light detection allows us to reject the dominant background of $\alpha$ particles, as proven by the CUPID-0 and CUPID-Mo demonstrators. In this work we present the results of the first test of the CUPID baseline module. In particular, we propose a new optimized detector structure and light sensors design to enhance the engineering and the light collection, respectively. We characterized the heat detectors, achieving an energy resolution of (5.9 ± 0.2) keV FWHM at the Q-value of ${}^{100}$Mo (about 3034 keV). We studied the light collection of the baseline CUPID design with respect to an alternative configuration which features gravity-assisted light detectors’ mounting. In both cases we obtained an improvement in the light collection with respect to past measures and we validated the particle identification capability of the detector, which ensures an $\alpha$ particle rejection higher than 99.9%, fully satisfying the requirements for CUPID.