Shell structure beyond the proton drip line studied via proton emission from deformed 141Ho

Fine structure in proton emission from the 7/2−[523]7/2−[523] ground state and from the 1/2+[411]1/2+[411] isomer in deformed nucleus 141Ho was studied by means of fusion-evaporation reactions and digital signal processing. Proton transitions to the first excited 2+ state in 140Dy, with the branching ratio of Ipgs(2+)=0.9±0.2% and Ipm(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 140Dy as predicted by the self-consistent theory. Implications of this result on coexistence effects around N=74N=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.