Shell structure beyond the proton drip line studied via proton emission from deformed Ho

Fine structure in proton emission from the 7/2−[523] ground state and from the 1/2[411] isomer in deformed nucleus Ho was studied by means of fusion-evaporation reactions and digital signal processing. Proton transitions to the first excited 2 state in Dy, with the branching ratio of Igs p (2 )=0.9±0.2% and Ip (2 )=1.7±0.5%, were observed. The data are analyzed within the non-adiabatic weak coupling model assuming a large quadrupole deformation of the daughter nucleus Dy as predicted by the self-consistent theory. Implications of this result on coexistence effects around N=74 are discussed. Significant modifications of the proton shell structure when going from the valley of beta stability to the proton drip line are discussed in terms of self-consistent theory involving the two-body tensor interaction.