S. Bouneau

Confirmation of the existence of a superdeformed rotational band in192Pb

A controversy has arisen over the existence, or not, of a superdeformed rotational band in192Pb. We have carried out an experiment using the168Er(3OSi, 6n)192Pb reaction at 159 MeV and have observed the coincidentγ rays in the EUROGAM 2 spectrometer. We confirm the original result of Henry et al. that a superdeformed band exists in192Pb.

Odd-even effects in fission induced by heavy ions

About eighty nuclei in the A≈100 mass region have been observed as fission fragments following the fusion evaporation 28,30Si+176Yb at 145 MeV bombarding energy. These nuclei have been identified from their γ-ray cascades detected with the EUROGAM2 array. The level schemes of several stable or neutron-rich nuclei have been extended to higher spins. From coincidences between transitions in complementary fragments, γ-rays de-exciting new high-spin states of hitherto unexplored isotopes can be assigned and some aspects of the fission mechanism can be studied.

Magnetic Rotation In 196Pb

A detailed spectroscopic study of high‐spin states in 196Pb has been carried out using the EUROBALL spectrometer array. Five new magnetic‐rotational bands have been found and the previously known bands have been extended. With one exception, all the bands have been connected to lower‐lying states and excitation energies, spins and parities have been determined. Doppler‐broadend lineshapes have been analyzed and lifetimes of states in four of the bands have been determined. The B(M1) values show the decrease with increasing spin that is expected for shears bands. Configurations of proton‐particle excitations coupled to neutron‐hole states have been assigned to the bands.

Octupole vibrations of the superdeformed196Pb nucleus

The study of the superdeformed (SD)196Pb nucleus has been revisited using the Eurogam Phase 2 spectrometer. All of the three observed excited SD bands were found to decay to the yrast SD band through, presumably,E1 transitions, allowing relative spin and excitation energy assignments. Comparisons with calculations using the random-phase approximation suggest that all three excited bands can be interpreted as octupole vibrational structures.