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

Abstract

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$)\ge 6.8\times 10^{15}$ yr and $T_{1/2}{(}^{186}$Os$)\ge 3.3\times 10^{17}$ 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.

19 pages, 6 figures, 5 tables

References in corpus (5)

• \textsc{MaGe} - a {\sc Geant4}-based Monte Carlo Application Framework for Low-background Germanium Experiments
• First observation of alpha decay of 190-Pt to the first excited level (E_{exc}=137.2 keV) of 186-Os
• Half-lives of $\alpha$ decay from natural nuclides and from superheavy elements
• Radiopurity of CaWO${}_4$ Crystals for Direct Dark Matter Search with CRESST and EURECA
• Search for $\alpha$ decay of naturally occurring Hf-nuclides using a Cs${}_2$HfCl${}_6$ scintillator

Cited by in corpus (5)

• The last Complex WIMPs standing
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• A first test of CUPID prototypal light detectors with NTD-Ge sensors in a pulse-tube cryostat
• New experimental limits on double-beta decay of osmium
• Updated and novel limits on double beta decay and dark matter-induced processes in platinum