https://doi.org/10.1140/epjc/s10052-021-08918-y
Regular Article – Experimental Physics
Search for double 
-decay modes of 
Zn using purified zinc
1
Dipartimento di Fisica, Sapienza Università di Roma, 00185, Rome, Italy
2
INFN-Sezione di Roma, 00185, Rome, Italy
3
Dipartimento di Fisica, Università di Milano-Bicocca, 20126, Milan, Italy
4
INFN-Sezione di Milano-Bicocca, 20126, Milan, Italy
5
Gran Sasso Science Institute, 67100, L’Aquila, Italy
6
INFN-Laboratori Nazionali del Gran Sasso, Assergi, 67100, L’Aquila, Italy
7
Dipartimento di Fisica, Università di Genova, 16146, Genoa, Italy
8
INFN-Sezione di Genova, 16146, Genoa, Italy
9
National Science Center Kharkov Institute of Physics and Technology, 61108, Kharkov, Ukraine
10
Karazin Kharkov National University, 61022, Kharkov, Ukraine
11
Department of Physics and Astronomy, University of South Carolina, 29208, Columbia, SC, USA
12
University of California, 94720, Berkeley, CA, USA
13
Physics Department, Queen’s University, K7L 3N6, Kingston, ON, Canada
Received:
9
December
2020
Accepted:
25
January
2021
Published online:
2
February
2021
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 Zn, setting the currently most stringent lower limits on their half-lives, 
(90% CI), and 
(90% CI), respectively.
© The Author(s) 2021
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Funded by SCOAP3.
