Nuclear resonant elastic scattering

The shape resonances have been described by Feshbach in elastic scattering cross-section for the processes of neutron capture and nuclear fission [7] in the cloudy crystal ball model of nuclear reactions. These scattering theory is dealing with configuration interaction in multi-channel processes involving states with different spatial locations. Therefore these resonances can be called also Feshbach shape resonances. These resonances are a clear well established manifestation of the non locality of quantum mechanics and appear in many fields of physics and chemistry [8,192] such as the molecular association and dissociation processes. 

Nuclear Resonant Inelastic and Quasi-Elastic Scattering.1454... 

The nuclear resonant inelastic and quasi-elastic scattering method has distinct features favorable for studies concerning the microscopic dynamics (i.e., lattice vibration, diffusion, and molecular rotation) of materials. One advantageous feature is the ability to measure the element-specific dynamics of condensed matter. For example, in solids the partial phonon density of states can be measured. Furthermore, measurements under exotic conditions -such as high pressure, small samples, and thin films - are possible because of the high brilliance of synchrotron radiation. (For the definition of brilliance, see O Sect. 50.3.4.5 of Chap. 50, Vol. 5, on Particle Accelerators. ) This method is applicable not only to solids but also to liquids and gases, and there is no limitation concerning the sample temperature. 

Since the nuclear resonant scattering is a coherent elastic process it is impossible to identify the scattering atom in the sample. Instead, for each individual resonant nucleus there is a small probability that this nucleus is excited. The summation of all these small amplitudes gives the total probability amplitude for a photon to interact resonantly with the nuclei. If the incident radiation pulse is short compared to the nuclear lifetime Tq. these probability amplitudes exhibit the same temporal phase. As a result, a collectively excited state is created, where a single excitation is coherently distributed over the resonant atoms of the sample [44]. The wave function of this collectively excited state is given by a coherent... 

R. Rohlsberger, Coherent elastic nuclear resonant scattering, in Nuclear Condensed Matter Physics with Synchrotron Radiation—Basic Principles, Methodology and Applications, Springer, Berlin, 2004, pp. 67-180. 

A development of synchrotron radiation facility made possible to perform the nuclear resonant scattering with synchrotron radiation. Elastic scattering is identical, in principle, to the Mossbauer resonance by y photons from radioactive nuclei. From the inelastic scattering one can observe the scattering involved phonon annihilation and creation in solid. Nuclear resonant scattering with synchrotron radiation will briefly described in final part of this chapter. 

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