Order out of chaos in atomic nuclei

Abstract

The transition from the resonance reaction mechanism at low level density to the direct reaction mechanism at high level density is investigated by means of numerical results obtained from microscopic calculations for nucleon induced reactions. The transition takes place rather sharply at Gamma approximately=D. Here, two types of motion of the nucleons exist simultaneously: a motion in long-lived states which are near equilibrium and a motion in short-lived states which are far from equilibrium. A formation of order out of chaos takes place only in the open quantum mechanical nuclear system. It is caused by quantum fluctuations via the continuum.