Search for double \(\beta\)-decay modes of \(^{64}\)Zn using purified zinc

• Published in: arXiv.org 2020-12
• Main Authors: Bellini, F, Beretta, M, Cardani, L, Carniti, P, Casali, N, Celi, E, Chiesa, D, Clemenza, M, Dafinei, I, S Di Domizio, Ferroni, F, Gironi, L, Gorbenko, Yu V, Gotti, C, Kovtun, G P, Laubenstein, M, Nagorny, S, Nisi, S, Pagnanini, L, Pattavina, L, Pessina, G, Pirro, S, Previtali, E, Rusconi, C, Schaffner, K, Shcherban, A P, Solopikhin, D A, Virich, V D, Tomei, C, Vignati, M
• Format: Article
• Language: English
• Subjects: Beta decay; Electron capture; Germanium; Nuclides; Positron emission; Purity; Radioisotopes; Zinc
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2012.05873

The production of ultra-pure raw material is a crucial step to ensure the required background level in rare event searches. In this work, we establish an innovative technique developed to produce high-purity (99.999%) granular zinc. We demonstrate the effectiveness of the refining procedure by measuring the internal contaminations of the purified zinc with a high-purity germanium detector at the Laboratori Nazionali del Gran Sasso. The total activity of cosmogenic activated nuclides is measured at the level of a few mBq/kg, as well as limits on naturally occurring radionuclides are set to less than mBq/kg. The excellent radiopurity of the zinc sample allows us to search for electron capture with positron emission and neutrinoless double electron capture of \(^{64}\)Zn, setting the currently most stringent lower limits on their half-lives, \(T_{1/2}^{\varepsilon\beta^+} > 2.7 \times 10^{21}\text{yr}\) (90% C.I.), and \(T_{1/2}^{0\nu2\varepsilon}> 2.6 \times 10^{21}\text{yr}\) (90% C.I.), respectively.