Ponente
Descripción
The first spectroscopy of $^{78}$Ni suggested that the nucleus act as separation between a region. of sphericity and an island of deformation developing around N=50 for Z<28. In Fe isotopes, the spectroscopy with in-flight studies reached until $^{72}$Fe and $^{73}$Co (N=46), discovering an extension of the N=40 island of inversion towards the N=50 magic number. Also in $^{69,71}$Co low-lying excited states were interpreted as arising from an intruder band becoming approaching the spherical states in energy. Achieving or even extending partial spectroscopy of the level schemes of isotopes at and beyond the mid shell N=45 ($^{71-73}$Co, $^{71,72$Fe) would allow exploring shell evolution towards the predicted N=50 island of inversion.
Beta-decay, as well as isomer-decay, studies are missing in this region. Beta decay has large beta-delayed neutron emission branches owing to the large Q values (>12 MeV) for $^{71,72}$Mn and $^{73,74}$Fe. Therefore, beta-decay spectroscopy of $^{71,72}$Mn will populate excited levels in $^{70,71}$Fe and beta decay of 73,74Fe excited levels in $^{72,73}$Co. Search for seniority isomers in $^{75-77}$Co could also provide information on the level schemes of these nuclei. The isotopes of interest will be produced by the fragmentation-fission of a primary $^{238}$U beam on the RIBF Be target. The separated fragmentation products will be implanted in the WAS3ABI Si array. The $\beta$-delayed $\gamma$-rays as well as the isomer decays will be studied with the HPGe array.
