Proton h211sub(/)2 and octupole excitations in 66148Dy82 and 66149Dy83

The yrast states of 148Dy and 149Dy have been studied by γ-ray and conversion electron measurements in (α, xn) and (16O,xn) reactions on enriched 152Gd and 136Ce targets. Level schemes to above 4 MeV for the two nuclei are reported. The πh211sub(/)2 spectrum identified in 148Dy and the πh11sub(/)2 effective charge esub(e)sub(f)sub(f) = 1.52 +- 0.05e, derived from the measured E2 transition rate between the (πh211sub(/)2) 10+ and 8+ states, are discussed and compared with results for other two-particle nulcei. The yrast cascades in 148Dy, and 149Dy continue above the (πh211sub(/)2) 10+ and (πk211sub(/)2 vf7sub(/)2) 27/2- states by approx. MeV E1 transitions de exciting the lowest members of octupole multiples built on these states. The energy shifts for the observed members of the πh211sub(/)2 x 3- multiplet are analyzed in terms of twoparticle-phonon exchange coupling using an empirical coupling strength extracted from the one valence particle nucleus 147Tb. The dominant vf7/2 x 3- character of low-lying 13/2+ isomers in 149Dy and other N = 83 nuclei is emphasized. (orig.)