https://doi.org/10.1140/epja/s10050-024-01371-x
Regular Article - Experimental Physics
Final results of the measurement to search for rare decays of naturally occurring osmium isotopes with ultra-low background gamma-ray spectrometry
1
INFN, Sezione Roma “Tor Vergata”, 00133, Rome, Italy
2
Dipartimento di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
3
INFN, Sezione Roma, 00185, Rome, Italy
4
Dipartimento di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
5
Institute for Nuclear Research of NASU, 03028, Kiev, Ukraine
6
INFN, Laboratori Nazionali del Gran Sasso, 67100, Assergi, AQ, Italy
7
INFN, Laboratori Nazionali di Legnaro, 35020, Legnaro, Italy
8
Faculty of Physics, Taras Shevchenko National University of Kyiv, 03022, Kiev, Ukraine
9
National Science Center “Kharkiv Institute of Physics and Technology”, 61108, Kharkiv, Ukraine
10
V.N. Karazin Kharkiv National University, 4, 61022, Kharkiv, Ukraine
11
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France
12
John de Laeter Centre for Isotope Research, Curtin University, GPO Box U 1987, Bentley, WA, Australia
Received:
21
March
2024
Accepted:
23
June
2024
Published online:
20
July
2024
A long-term measurement was conducted to search for α, double-α and double-β decays with γ quanta emission in naturally occurring osmium isotopes. This study took advantage of two ultra-low background HPGe detectors and one ultra-low background BEGe detector at the Gran Sasso National Laboratory (LNGS) of the INFN. Over almost 5 years of data were taken using high-purity osmium samples of approximately 173 g. The half-life limits set for α decays of 184Os to the first 2+ 103.6 keV excited level of 180W (T1/2 ≥ 9.3 × 1015 yr) and of 186Os to the first 2+ 100.1 keV of 182W (T1/2 ≥ 4.8 × 1017 yr) exceed substantially the present theoretical predictions that are at level of T1/2 ~ (0.6–3) × 1015 yr for 184Os and T1/2 ~ (0.3–2) × 1017 yr for 186Os. New half-life limits on the 2EC and ECβ+ decay of 184Os to the ground and excited levels of 184W were set at level of T1/2 > 1016–1017 yr; a lower limit on the 2β– decay of 192Os to the 2+ 316.5 keV excited level of 192Pt was estimated as T1/2 ≥ 6.1 × 1020 yr. The half-life limits for 2α decay of 189Os and 192Os were set for the first time at level of T1/2 > 1020 yr.
G. P. Kovtun deceased.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
