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Marie-Genevieve Porquet
CSNSM, Orsay High-spin structure of neutron-rich nuclei produced by heavy-ion induced fissionUsing the Euroball4 array at Strasbourg, we have recently performed several experiments devoted to the study of high-spin states of nuclei with A 80 - 130, produced from ssion following the fusion reactions, 30 Si + 176 Yb at 145 MeV bombarding energy, 31 P + 176 Yb at 152 MeV and 18 O + 208 Pb at 85 MeV. In such experiments, each scission fragment can be identified from the gamma-ray cascades deexciting its excited states. Moreover, from gamma-ray coincidences measured between transitions in complementary fragments, gamma-ray deexciting new high-spin states of hitherto unexplored isotopes can be assigned. From these experiments and previous ones performed with Eurogam2 at Strasbourg [1-5] and Euroball3 at Legnaro [6], level schemes of many stable and neutron-rich nuclei have been extended or newly established up to, in some cases, spin 18 hbar and excitation energy 8 MeV. We will present the new experimental results obtained in some neutron- rich odd-Z nuclei from 41 Nb to 53 I. All the band-head configurations have been identified from the behaviour of the collective bands built on them. Therefore the single-proton states, located around the Fermi levels for Z = 41 to 53, can be discussed as a function of the neutron number (and the deformation). In all these isotopic series, three-quasiparticle states have been measured above 2 MeV excitation energy. The case of 49 In nuclei [7] will be discussed in the framework of shell-model calculations. Futhermore the individual identification of each fragment by means of its emitted transitions allows us to have a new insight into the mechanism of scission induced by heavy ions. The last results will be reported. References: [1] F. Hoellinger et al., Eur. Phys. J. A4 (1999) 319
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Last modificated: 2003-09-22
