Speaker: Ludovic Bonneau (CENBG, France)

Microscopic Fission Barriers of heavy nuclei and angular momentum of fission fragments

After a brief general introduction, I will present the work that I have carried out as a PhD student about microscopic calculations of the spin of fission fragments around scission point. These calculations rely on a model recently developed by I.N. Mikhailov and P. Quentin (1999), called ``orientation pumping''. To perform this study involving very large deformations around scission, we first check the validity of our HF(SkM*)+BCS mean field microscopic approach at lower deformations upon calculating fission barriers. We have obtained a globally satisfying agreement with experimental data. Then we have studied realistic scission configurations. We have found that, for several heavy nuclei ranging from Thorium to Nobelium isotopes, the energetically favored fragmentation stands fairly close to the one corresponding to the maximum of the experimental mass yield distribution. Finally we have applied the orientation pumping model which requires to calculate the expected value of the non local J^2 operator for each fragment from the whole system wave function. The orientation pumping alone can generate spin-values of roughly 3 to 5 hbar in each fragment, in fairly good agreement with recent experimental data.