Coherent and Semicoherent Neutron Transfer Reactions III: Phonon Frequency Shifts

A new model describing the transfer of neutrons to and from nuclei embedded in a lattice was recently proposed. The coupling between the nuclei and lattice phonons is now explored, focusing on the question of whether it is possible under any conditions for anomalously large energy transfer to or from the lattice to occur during a neutron transfer reaction. By studying the gamma line shape, no anomalies are expected for a ground-state lattice or for a thermal lattice. Under certain conditions, the frequency of aphonon mode can be shifted significantly in a neutron transfer reaction; phonons initially present in that mode are shifted in frequency during the reaction. This effect produces an anomalous energy shift in the event that the mode is initially strongly excited.