Search for alpha decay of naturally occurring osmium nuclides accompanied by gamma quanta

• Published in: arXiv.org
• Main Authors: Belli, P, Bernabei, R, Cappella, F, Caracciolo, V, Cerulli, R, Danevich, F A, Incicchitti, A, Kasperovych, D V, Kobychev, V V, Kovtun, G P, Kovtun, N G, Laubenstein, M, Poda, D V, Polischuk, O G, Shcherban, A P, Tessalina, S, Tretyak, V I
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 03.09.2020
• Subjects: Alpha decay; Beta decay; Germanium; Isotopes; Mass spectrometry; Nuclei; Nuclides; Osmium; Osmium isotopes; Physics - Nuclear Experiment
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2009.01508

A search for \(\alpha\) decay of naturally occurring osmium isotopes to the lowest excited levels of daughter nuclei has been performed by using an ultra-low-background Broad-Energy Germanium \(\gamma\)-detector with a volume of 112 cm\(^3\) and an ultra-pure osmium sample with a mass of 118 g at the Gran Sasso National Laboratory of the INFN (Italy). The isotopic composition of the osmium sample has been measured with high precision using Negative Thermal Ionisation Mass Spectrometry. After 15851 h of data taking with the \(\gamma\)-detector no effect has been detected, and lower limits on the \(\alpha\) decays were set at level of \(\lim T_{1/2}\sim 10^{15}-10^{19}\) yr. The limits for the \(\alpha\) decays of \(^{184}\)Os and \(^{186}\)Os to the first excited levels of daughter nuclei, \(T_{1/2}(^{184}\)Os\()\geq 6.8\times10^{15}\) yr and \(T_{1/2}(^{186}\)Os\()\geq3.3\times10^{17}\) yr (at 90% C.L.), exceed the present theoretical estimates of the decays half-lives. For \(^{189}\)Os and \(^{192}\)Os also decays to the ground states of the daughter nuclei were searched for due to the instability of the daughter nuclides relative to \(\beta\) decay.