First Observation Of Two-Proton Radioactivity Of ~(45)Fe

摘要

In experiments at the FRS of GSI and at the SISSI-LISE3 facility of GANIL, the decay of the proton drip-line nucleus ~(45)Fe has been studied after projectile fragmentation of a ~(58)Ni primary beam. Fragment-implantation events have been correlated with radioactive decay events in silicon telescopes on an event-by-event basis. The decay-energy spectrum of ~(45)Fe implants shows a distinct peak consistent with a two-proton ground-state decay of ~(45)Fe. None of the events in the peak were found to be in coincidence with γ radiation or with β particles which were searched for in the telescope-surrounding detectors. The decay energy for ~(45)Fe agrees nicely with several theoretical predictions for two-proton emission. These predictions strongly support the observed decay to be a simultaneous two-proton ground-state decay.