Speaker
Description
A search for $\alpha$ and $\beta\beta$ decays of naturally occurring osmium isotopes to the excited levels of daughter nuclei has been performed using an ultra-low-background broad-energy germanium $\gamma$ detector and an ultrapure osmium sample at the Gran Sasso National Laboratory of the INFN (Italy).
The isotopic composition of the osmium sample has been measured with a high precision using negative thermal ionization mass spectrometry.
During the data taking with the $\gamma$ detector, no effect has been detected, and lower limits of the half-life of $\alpha$ and $\beta\beta$ decays were set at the level of $10^{15}–10^{20}$ yr.
In the case of $\alpha$ decays of $^{184}$Os and $^{186}$Os to the first excited levels of daughter nuclei, the limits substantially exceed the present theoretical estimates of the decays probabilities. This gives hope to the possibility to detect such transitions in the next data taking.
The present talk will describe a review of recent new measurements and new experimental perspectives.
