S. Flibotte

Multi-particle excitations in the superdeformed 149Gd nucleus

Abstract Six rotational bands built on superdeformed intrinsic configurations have been observed in the 149 Gd nucleus with the Eurogam spectrometer. Orbital configuration assignments have been suggested on the basis of their effective alignments calculated with the Nilsson-Strutinsky cranking model. Most of the excited bands have identical partners in neighboring nuclei including one case differing by four mass units. Measurements of feeding patterns indicate that the 149 Gd yrast superdeformed band is fed over a wider range of angular momentum than other yrast superdeformed bands in this mass region whereas weaker excited bands in the same nucleus are populated in narrower spin windows.

Neutron excitations across the N = 86 superdeformed shell gap

Abstract Based on data obtained with the Eurogam spectrometer, a systematic investigation of superdeformed bands built on single neutron excitations across the N = 86 shell gap has been carried out for gadolinium, terbium, and dysprosium isotopes with 85 ≤ N ≤ 87. In each nucleus, pairs of bands corresponding to degenerate signature partners have been observed. The effective alignment is constant and close to zero for many of the bands, in agreement with cranked shell model calculations for the [402]5/2 and [514]9/2 orbitals. Several bands exhibit non-zero alignments, indicating in some cases the influence of pairing correlations even at high spin and in other cases the occupancy of the [521]3/2 orbital.

High spin states in the nucleus150Tb

Excited states in the nucleus150Tb have been investigated up to spin 39ħ and 13 MeV excitation energy using the130Te(27Al, 7n) reaction and the EUROGAM array. The theoretical interpretation of the observed states has been performed in the framework of the deformed independent particle model. The analysis of the decay out of the yrast superdeformed band indicates that normal-deformed states with spins between 24ħ and 28ħ are fed.

The first results from EUROGAM : superdeformed structures in 151Tb

Abstract An experiment has been carried out using the Eurogam array which consisted of 42 escape suppressed germanium detectors in order to study the properties of the superdeformed structures in 151 Tb. A first 4-dimensional analysis of the data show that these superdeformed bands decay out at different rotational frequencies, with the yrast superdeformed band decaying out at much larger rotational frequency. New γ-rays has been added to the yrast and excited superdeformed bands and the remarkable similarity in γ-ray transitions energies between the identical bands in 151 Tb and 152 Dy has been confirmed over a quite large range of rotational frequencies.