Speaker
Description
The ILIMA (Isomers, LIfetimes, and MAsses) collaboration aims at precision measurements of atomic masses and lifetimes of exotic nuclei and isomers, as well as the exploration of rare decay phenomena of highly-charged (radioactive) ions. Originally it was planned to carry out this unique research program at dedicated new storage rings to be built with the FAIR project. However, since these constructions have been postponed to a later stage, the collaboration is now continuing to employ and extend their program with new and upgraded detector setups at the existing Experimental Storage Ring (ESR).
I will give an overview about recent experiments measuring rare decay modes that can only appear in highly-charged ions. The measurement of the bound-state beta-decay of 205Tl(81+) has been proposed 30 years ago. However, only recently it could be measured at the ESR and its astrophysical impact on the production of the short-lived radioactive s-only isotope 205Pb [G. Leckenby et al., Nature 635, 321 (2024)] and the potential measurement of the long-term solar neutrino flux in the LOREX project [R.S. Sidhu, PRL 133, 232701 (2024)] be determined.
Another highlight has been the measurement of the isolated two-photon decay in 72Ge [D. Freire-Fernandez et al., PRL 133, 022502 (2024)] where the first excited state is a 0+ state at 691 keV. This second-order electromagnetic process normally competes with internal conversion in neutral atoms and electron-positron pair creation if the excited state is above the 1022 keV production threshold. In fully ionized 72Ge(32+) the partial half-life of the 0+ state was measured to be ~24 ms and thus deviates strongly from expectations.
These recent successes have motivated many new measurements and proposals, highlighting the bright future of the ILIMA@ESR collaboration in the next years.
