https://doi.org/10.1140/epja/s10050-024-01260-3
Regular Article - Experimental Physics
Search for alpha and double alpha decays of natural Nd isotopes accompanied by gamma quanta
1
INFN Sezione Roma “Tor Vergata”, 00133, Rome, Italy
2
Dipartimento di Fisica, Università di Roma “Tor Vergata”, 00133, Rome, Italy
3
Institute for Nuclear Research of NASU, 03028, Kiev, Ukraine
4
National University of Life and Environmental Sciences of Ukraine, 03041, Kiev, Ukraine
5
INFN Sezione Roma, 00185, Rome, Italy
6
Dipartimento di Fisica, Università di Roma “La Sapienza”, 00185, Rome, Italy
7
INFN, Laboratori Nazionali del Gran Sasso, 67100, Assergi, AQ, Italy
8
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France
Received:
20
October
2023
Accepted:
4
February
2024
Published online:
1
March
2024
From 7 naturally occurring Nd isotopes, 5 are unstable in relation to α decay. If an excited level of the daughter nucleus is populated, or the daughter nucleus is unstable, γ quanta can be emitted. We used an ultra-low background spectrometry system with 4 high purity germanium (HPGe) detectors (about 225 cm3 volume each) to search for such decays using a highly purified Nd-containing sample with mass of 2.381 kg. Measurements were performed at the INFN Gran Sasso underground laboratory (with an overburden of about 3600 m w.e.) during 51,237 h. Half-life limits for α decays of 143Nd and 145Nd were determined to be T1/2(143Nd) > 1.1 × 1020 year and T1/2(145Nd) > 2.7 × 1019 year at 90% C.L. This is an increase of three and two orders of magnitude, respectively, compared with the most restrictive values currently given in literature. A limit for α decay of 144Nd to the excited level of 140Ce with Eexc = 1596.2 keV was determined for the first time as T1/2(144Nd → 140Ce*) > 9.3 × 1020 year. Restriction for the α decay of 146Nd to the excited level of 142Ce with Eexc = 641.3 keV was increased by 3 orders of magnitude to T1/2(146Nd → 142Ce*) > 1.4 × 1021 year. For α and 2α decays of 148Nd, first T1/2 limits were set as 4.2 × 1018 year and 2.1 × 1020 year, respectively.
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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.
