Effect of pairing on nuclear dynamics
Guillaume Scamps
東北大理
日時：2014年10月28日（火） 14:00-
場所：理学研究科合同B棟 7階 743号室
Pairing correlations is an essential component for the description of the atomic nuclei. The effects of pairing on static property of nuclei are now well known. During this work, the effect of pairing on nuclear dynamics have been investigated. Theories that includes pairing are benchmarked in a model case. The TDHF+BCS theory turns out to be a good compromise between the physics taken into account and the numerical cost. This TDHF+BCS theory was retained for realistic calculations. Nevertheless, the application of pairing in the BCS approximation may induce new problems due to (1) the particle number symmetry breaking, (2) the non-conservation of the continuity equation. These difficulties are analysed in detail and solutions are proposed. A 3 dimensional TDHF+BCS code is developed to simulate the nuclear dynamic. Applications to giant resonances show that pairing modify only the low lying peaks. The high lying collective components are only affected by the initial conditions. An exhaustive study of the giant quadrupole resonances with the TDHF+BCS theory is performed on more than 700 spherical or deformed nuclei. Is is shown that the TDHF+BCS theory reproduces well the collective energy of the resonance. After validation on the small amplitude limit problem, the approach is applied to study nucleon transfer in heavy ion reactions. A new method to extract transfer probabilities is introduced. It is demonstrated that pairing significantly increases the two-nucleon transfer probability. Application of this theory is also done to study the fission process. Most of the microscopic approaches assume an adiabatic path. This approximation is valid for the crossing of the barrier but the adiabaticity is known to break down at the scission. Then, the TDHF+BCS theory is used to reproduce this evolution and gives results close to the experimental one.