Laser-Nucleus Interactions: Towards the Sudden Regime
The interaction between medium-weight nuclei and a strong zeptosecond laser pulse of MeV photons is investigated theoretically. Due to the very fast nuclear equilibration, multiphoton absorption can occur. We focus on the sudden regime of interaction where the photon absorption rate is so strong that it prevents complete nuclear equilibration after each photon absorption process. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption and its counterpart stimulated dipole emission, equilibration and neutron evaporation in a decay chain of nuclei. As a new aspect we keep track of the nuclear equilibration by considering the particle-hole states and their interactions as photons are absorbed by the forming compound nucleus. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron evaporation and provide relevant information for future experiments.