The level structures of146Gd and147Gd have been investigated by in-beamgamma-ray ande – spectroscopy with (agr, xn) reactions on enriched Sm targets. Detailed level schemes up to sim4 MeV, which differ radically from earlier schemes, are reported. The energy levels are characterized as particle-hole excitations using empirical single particle energies and two nucleon interactions. Analysis of pure 1p 1h proton excitations demonstrates that theZ=64 andN=82 energy gaps are about equally large

The yrast states of 148Dy and 149Dy have been studied by ?-ray and conversion electron measurements in (c~,xn) and (160, xn) reactions on enriched ~S2Gd and ~36Ce targets. Level schemes to above 4MeV for the two nuclei are reported. The ~h~/2 spectrum identified in 148Dy and the ~haa/2 effective charge eeff=l.52_+0.05e, derived from the measured E2 transition rate between the (rch~/2) 10 + and 8 + states, are discussed and compared with results for other two-particle nuclei. The yrast cascades in a48Dy and a49Dy continue above the (Tzh2a/2) 10 + and (zchZ~/2vfT/2) 27/2-states by --~1 MeV E1 transitions de-exciting the lowest members of octupole multiplets built on these states.The energy shifts for the observed members of the 7zh21/2 • 3-multiplet are analyzed in terms of twoparticle-phonon exchange coupling using an empirical coupling strength extracted from the one valence particle nucleus 14VTb. The dominant vf7/2 x 3-character of low-lying 13/2 + isomers in 149Dy and other N = 83 nuclei is emphasized.

No abstract

From a shell model analysis of high-spin states in neutron deficient nuclei above ~46Gd we have derived the ground state masses of the N= 82 and 83 isotones of Eu, Tb, Dy, Ho, and Er. The results can be used to calculate the energies of aligned multiparticle yrast configurations. They also link ten a-decay chains to the nuclei with known masses, providing many new absolute mass values which are compared with predictions. An examination of the two-proton separation energies at N=82 shows an 0.5 MeV break in the nuclear mass surface at Z = 64.

No abstract