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

Fine structure in proton emission from the 7/2(-)[523] ground state and from the 1/2(+)[411] isomer in deformed nucleus Ho-141 was studied by means of fusion-evaporation reactions and digital signal processing. Proton transitions to the first excited 2(+) state in Dy-140, with the branching ratio of I-p(gs) (2(+)) = 0.9 +/- 0.2% and I-m(p)(2(+)) = 1.7 +/- 0.5%, were observed. The data are analyzed within the non-adiabatic weak coup. pling model assuming a large quadrupole deformation of the daughter nucleus Dy-140 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. (C) 2008 Elsevier B.V. All rights reserved.