Shell structure beyond the proton drip line studied via proton emission from deformed \u3csup\u3e141\u3c/sup\u3eHo

Fine structure in proton emission from the 7 / 2- [523] ground state and from the 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 Ipg s (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 = 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. © 2008 Elsevier B.V