Electron screening effects on a-decay

An open problem in Nuclear Astrophysics concerns the understanding of electronscreening ffects on nuclear reaction rates at stellar energies. In this framework, we have proposed to nvestigate the influence of the electron cloud on α-decay by measuring Q-values and α-decay half-lives of fully stripped, H-like and He-like ions. These kinds of measurements have been feasible just recently for highly-charged radioactive nuclides by fragmentation of ²³⁸U at relativistic energies at the FRS-ESR facility at GSI. In this way it is possible to produce, efficiently separate and store highlycharged α-emitters. Candidates for the proposed investigation were carefully selected and wiU be studied by using the Schottky Mass Spectroscopy technique. In order to establish a solid reference data set, lifetimes and Q _α-value measurements of the corresponding neutrals have been performed directly at the FRS, by implanting the separated ions into an active SiUcon stopper.