D. Hojman

The low-spin states in the doubly odd 182Ir nucleus and the influence of the proton-neutron interaction

Abstract Low-spin states of 182 Ir populated through the β + EC decay of 182 Pt were studied using the ISOCELE facility. A low-spin level scheme has been established. Using a semi-microscopic rotor-plus-two-quasiparticle model developed in the context of the HF + BCS approximation, the influence of the V pn interaction on the relative energy location of excited states has been studied and the low-spin states located at low energy in 182 Ir have been identified. The α-decay energy of 186 Au has been corrected to 4907 ± 16 keV.

Spin and parity of isomeric and ground states of the doubly-odd nucleus184Au

Low-spin states in doubly-odd184Au have been populated in the β+/EC decay of184Hg produced by bombarding184Sm targets with an 185 MeV40Ar beam. Radioactive Hg nuclei were transported by a He jet system. A new level scheme has been established from γ-γ-t and X-γ-t coincidence measurements. Spin and parity values Iπ=5+, Iπ =2+ and Iπ=3− were assigned to the ground state and the two isomeric states of184Au, respectively. The structure of these states is discussed using B(E1) values.

Rotational bands in201Pb

High-spin states in201P6 were populated in the192Os(14C, 5n)201Pb reaction at a beam energy of 70 MeV. Gamma-ray coincidences were measured with the Chateau de Cristal spectrometer array. Two rotational bands with rather regular energy spacings have been found. The data are interpreted in terms of collective bands built on proton particle-hole excitations coupled to i13/2neutrons at oblate deformation.

High spin states of189Au

High-spin states of189Au have been investigated through the174Yb(19F, 4n) reaction using in-beam gamma-ray spectroscopy techniques with the “Château de Cristal“ multidetector array. An extended level scheme is proposed.

Relative population of oblate and prolate structures in189Au

High spin states of189Au were populated via the174Yb (19F, 4n reaction at 86, 90, 95 and 100 MeV beam energies. The study of the relative population of oblate and prolate structures shows a striking disappearance of the prolate band relative to the oblate ones as the beam energy goes from 86 to 100 MeV.

Relative population of the oblate and prolate structures in187Au

The population of the oblate and the prolate structures in187Au has been studied using the “Château de Cristal” set-up through the172Yb(19F, 4n) reaction at 90, 95 and 100 MeV beam energy. γ — γ, γ-Fold and γ -Sum energy coincidence measurements were performed, γ-ray intensity measurements showed that as the beam energy increases the prolate system is less populated than the oblate one. Fold and Sum-energy associated with oblate and prolate structures showed a different behaviour with increasing beam energy. Two mechanisms are suggested to explain these results.