Coulomb excitation of rotational and vibrational states in 167Er, 163Dy and 155Gd

Abstract

Low-lying states in deformed odd-neutron rare-earth nuclei have been studied by Coulomb excitation with 36–52 MeV 16O ions. The gamma rays from the reaction were observed as single spectra in Ge(Li) detectors. In 167Er, the K0−2 and K0+2 gamma-vibrational bands were observed at 532 and 711 keV with B(E2)↑ = 2.6 and 2.5 s. p. u., respectively. In 163Dy, the K0−2 gamma-vibrational band was observed at 351 keV with B(E2)↑ = 1.2 s. p. u. The 32−|521| Nilsson state was observed at 422 keV with B(E2)↑ = 0.5 s. p. u. due to its Coriolis coupling to the ground band. In 155Gd, the K0−2 gamma-vibrational band was observed at 556 keV with B(E2)↑ = 1.6 s. p. u. The excitation of the 12−|530| Nilsson state at 422 keV with B(E2)↑ = 1.2 s. p. u. seems to be due to Coriolis coupling to the ground band. In this nucleus, indications were found for a beta-vibrational band at 592 keV and a K0+2 gamma-vibrational band at 1028 keV corresponding to B(E2)↑ ≧ 1.3 and 0.8 s. p. u.