Eur. Phys. J. C (2021) 81: 104
https://doi.org/10.1140/epjc/s10052-020-08809-8

Regular Article – Experimental Physics

Characterization of cubic Li${}_2$${}^{100}$MoO${}_4$ crystals for the CUPID experiment

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

^a cupid.publications@lngs.infn.it

Received: 9 December 2020
Accepted: 28 December 2020
Published online: 1 February 2021

Abstract

The CUPID Collaboration is designing a tonne-scale, background-free detector to search for double beta decay with sufficient sensitivity to fully explore the parameter space corresponding to the inverted neutrino mass hierarchy scenario. One of the CUPID demonstrators, CUPID-Mo, has proved the potential of enriched Li${}_2$${}^{100}$MoO${}_4$ crystals as suitable detectors for neutrinoless double beta decay search. In this work, we characterised cubic crystals that, compared to the cylindrical crystals used by CUPID-Mo, are more appealing for the construction of tightly packed arrays. We measured an average energy resolution of ($6.7\pm 0.6$) keV FWHM in the region of interest, approaching the CUPID target of 5 keV FWHM. We assessed the identification of $\alpha$ particles with and without a reflecting foil that enhances the scintillation light collection efficiency, proving that the baseline design of CUPID already ensures a complete suppression of this $\alpha$-induced background contribution. We also used the collected data to validate a Monte Carlo simulation modelling the light collection efficiency, which will enable further optimisations of the detector.