Result on the Neutrinoless Double Beta Decay Search of 82Se with the CUPID-0 Experiment

F Bellini ,S Capelli ,D Orlandi ,M Pallavicini ,L Cassina ,V Palmieri ,F Ferroni ,M Vignati ,K Schäffner ,S Morganti ,M Beretta ,A Cruciani ,N Casali ,P Gorla ,S Pozzi ,A D’addabbo ,C Gotti ,O Azzolini ,S Nisi ,C Rusconi ,O Cremonesi ,M Pavan ,M Clemenza ,M Biassoni ,L Canonica ,María Teresa Ruiz Barrera ,P Carniti ,V Pettinacci ,L Pagnanini ,C Nones ,S Pirro ,L Cardani ,S Nagorny ,L Pattavina ,L Gironi ,M Martinez ,C Bucci ,I Dafinei ,C Tomei ,A Giuliani ,S Di Domizio ,G Pessina ,A Puiu ,J W Beeman ,M Nastasi ,G Keppel ,E Previtali ,C Brofferio ,A Zolotarova

doi:10.3390/universe5010002

Abstract

CUPID-0 is the first large array of scintillating Zn 82 Se cryogenic calorimeters (bolometers) implementing particle identification for the search of the neutrinoless double beta decay (0 ν β β ). The detector consists of 24 enriched Zn 82 Se bolometers for a total 82 Se mass of 5.28 kg and it has been taking data in the underground LNGS (Italy) since March 2017. In this article we show how the dual read-out provides a powerful tool for the α particles rejection. The simultaneous use of the heat and light information allows us to reduce the background down to (3.2 − 1.1 + 1.3 )×10 − 3 counts/(keV kg year), an unprecedented level for cryogenic calorimeters. In a total exposure of 5.46 kg year Zn 82 Se we set the most stringent limit on the 0 ν β β decay 82 Se half-life T 1 / 2 0 ν > 4.0 × 10 24 year at 90% C.I.

Highlights

The neutrinoless double beta deca 0νββ [1] is a transition, in which a nucleus (A, Z) decays into its isobar (A, Z + 2) with the simultaneous emission of two electrons
The LD signal amplitude and shape is estimated applying the optimum filter at a fixed time delay compared to the Zn82 Se heat signal as detailed in Ref. [51]
Details of the analysis and the interval Bayesian lower limit on the 82 Se half life T1/2 procedure used to compute the upper limit can be found in Ref. [47,50]

Summary

Introduction

The neutrinoless double beta deca 0νββ [1] is a transition, in which a nucleus (A, Z) decays into its isobar (A, Z + 2) with the simultaneous emission of two electrons Both the parent and the daughter nucleus must be more bound than the intermediate one (A, Z + 1) in order to avoid the occurrence of the sequence of two single beta decays. Such a condition, due to the pairing term, is fulfilled in nature for 35 even-even nuclei [2]. Cryogenic calorimeters (usually called bolometers) play an important role in this field of research [15,16] and in this contribution we review the most recent results obtained by the CUPID-0 experiment

The Detector

Data Analysis and Results

Conclusions