Quantum Theory of Channeling Radiation
In the MeV region, the density of levels for the transverse motion of channeled electrons and positrons is so low that a quantum description must be applied. After the early papers on channeling radiation, especially by Kumakhov, many different theoretical approaches have been developed.1 Our treatment2 is based on the quantum formalism developed by Lervig et al.,3 and I shall try to show that this approach has important advantages. Through a systematic approximation procedure, a comprehensive and very accurate description can be built up, and the details under discussion are now corrections to photon energies at the 1% level, e.g., a correction from phonon scattering which is analogous to the Lamb shift of atomic levels. Experimentally, line energies can be determined with this precision,4 and applications of channeling radiation to study crystal properties such as electron densities5.6 and thermal vibrations7$ depend on the possibility of making theoretical predictions with an accuracy better than 1%.
KeywordsTransverse Energy Planar Channeling Line Shift Lamb Shift Perturbation Treatment
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