Experiments performed on Storage Rings have shown that lifetimes of beta-radionuclides can change dramatically as a function of the ionization state (e.g. the lifetime of the 187Re has been observed to collapse of nine orders of magnitude for the fully-stripped ion, due to the so-called “bound-state β decay”mode).
An even more attractive experiment may consist in measuring, for the first time, nuclear β-decay rates in stellar-like conditions, especially for radionuclides involved in nuclear-astrophysics processes and cosmology (BBN, s-processing, CosmoChronometers, Early Solar System formation). Compact magnetic plasma traps, where plasmas reach density ne~10^11-10^14 cm-3, and temperature Te~0.1-30 keV, are suitable for such studies. The decay rates can be measured as a function of the charge state distribution of the inplasma ions.
This idea is the subject of the PANDORA (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) project, now supported by the 5th Nat. Comm. of INFN as a feasibility study. A list of possible physics cases include 85Kr (a crucial branching point of the s-process); 176Lu and the pairs 187Re-187Os and 87Sr-87Rb, which play a crucial role as cosmo-clock; the 7Be, that is responsible of the primordial abundance of 7Li and in primordial nucleosynthesis happens in a quite peculiar plasma environment. The talk will give an overview about methodologies and experimental scenarios, starting from the results of the feasibility study and giving the perspectives about the construction of the fullscale setup in the next years.
Alessio Galatà