  The interaction between nuclei and a strong zeptosecond laser pulse with
coherent MeV photons is investigated theoretically. We provide a first
semi-quantitative study of the quasiadiabatic regime where the photon
absorption rate is comparable to the nuclear equilibration rate. In that
regime, multiple photon absorption leads to the formation of a compound nucleus
in the so-far unexplored regime of excitation energies several hundred MeV
above the yrast line. The temporal dynamics of the process is investigated by
means of a set of master equations that account for dipole absorption,
stimulated dipole emission, neutron decay and induced fission in a chain of
nuclei. That set is solved numerically by means of state-of-the-art matrix
exponential methods also used in nuclear fuel burnup and radioactivity
transport calculations. Our quantitative estimates predict the excitation path
and range of nuclei reached by neutron decay and provide relevant information
for the layout of future experiments.
