Special Article - New Tools and Techniques
Development of low-background CsZrCl detectors to study rare decays in Zr isotopes
Dipartimento di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
2 INFN, Sezione di Roma “Tor Vergata”, 00133, Rome, Italy
3 INFN, Sezione di Roma, 00185, Rome, Italy
4 Dipartimento di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
5 INFN Laboratori Nazionali del Gran Sasso, 67100, Assergi, AQ, Italy
6 Department of Physics, Engineering Physics and Astronomy, Queen’s University, K7L 3N6, Kingston, ON, Canada
7 Arthur B. McDonald Canadian Astroparticle Physics Research Institute, K7L 3N6, Kingston, ON, Canada
8 Department of Chemistry, Queen’s University, K7L 3N6, Kingston, ON, Canada
Accepted: 12 July 2023
Published online: 30 July 2023
In this work, we present the first complex study of CsZrCl (CZC) scintillating crystals in terms of their chemical purity, crystal radiopurity, scintillating performance and pulse-shape discrimination ability. An ICP-MS measurement exhibits a high purity of the CZC material (overall impurity level less than 10 g/g). The CZC crystals show a very low content of radionuclides from U/Th natural decay chains. For K and Cs only limits at the level few mBq/kg were set after more than 650 h of measurement with a high purity germanium (HPGe) detector. Nevertheless, they contained cosmogenic Cs with an activity of about 50 mBq/kg. The measurements with two CZC crystals (11 and 24 g) as scintillating detectors over 456.5 d in the low-background DAMA/CRYS facility, deep underground at LNGS, supported a substantial radiopurity of these crystals leading to a counting rate of 0.17 (kgkeVyr) at the of Zr (3.35 MeV). These detectors show a high particle-discrimination ability for and particles. Limits on the half-lives of the double beta decays (DBD) of Zr and of Zr with and without neutrinos emission were also set at the level – yr (90 C.L.). The detailed analyses of the internal background components will also be useful for further developments of CsZrCl low-background scintillating detectors and for the optimization of the experimental conditions.
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