The Coherent-Path Model for Nuclear Resonant Gamma-Ray Scattering: An Overview

A 'coherent-path' model for nuclear-resonant scattering of gamma radiation from resonant matter has been developed and is summarized here. The solution provides a unified microscopic picture of nuclear-resonant scattering processes. The coherent-path model shows that the 'speed-up' and 'dynamical beating' effects are primarily a consequence of the fact that a single 'effective' nuclear scattering process is 180o out of phase with the incident radiation. The model is used to explain and understand the results when applied to time-differential Moessbauer spectroscopy, time-differential synchrotron radiation spectroscopy, and the 'gamma echo'.