Two-proton radioactivity: the case of 45Fe.

According to most mass models, several of the best candidates for two-proton radioactivity lie in the A = 50 mass region, at the proton drip-line. Recent experiments using the fragmentation of a 58Ni beam allowed us to reach this region and observe some of these candidates, like 45Fe and 48Ni. During an experiment at the GANIL / LISE3 facility helded in 2000, we could identify 22 events of implantation of 45Fe nuclei. The energy distribution of the corresponding decay events shows a clear peak at (1.14 ± 0.04) MeV that could be assigned to the direct 2-proton emission from the ground state. This energy is in very good agreement with several theoretical predictions, and no coincident β particle has been observed experimentally. A half-life of (4.7[sub -1.4][sup +3.4]) ms has been measured for the decay of 45Fe. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]