One-body dissipation and chaotic dynamics in a classical simulation of a nuclear gas

In order to understand the origin of one-body dissipation in nuclei, we analyze the behavior of a gas of classical particles moving in a two-dimensional cavity with nuclear dimensions. This ''nuclear" billiard has multipole-deformed walls which undergo periodic shape oscillations. We demonstrate that a single-particle Hamiltonian containing coupling terms between the particle motion and the collective coordinate induces a chaotic dynamics for any multipolarity, independently of the geometry of the billiard. If the coupling terms are switched off, the "wall formula" predictions are recovered. We discuss the dissipative behavior of the wall motion and its relation to the order-to-chaos transition in the dynamics of the microscopic degrees of freedom. [S0556-2813(98)03911-9].