Interpretation of Scattering by Charged Particles and Photons

Published In

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Document Type


Publication Date

April 1994


Coulomb functions, Scattering (Physics), Helium -- Ionization -- Analysis, Dispersion relations


In principle, Coulomb scattering by charged particles may be described by contributions from n-photon terms, corresponding to the nth order terms in the Born expansion for charged particles. Consequently, one may relate scattering by charged particles to scattering by photons. Thus Raman scattering, second-order Compton scattering, the Auger effect, and two electron transitions in high velocity collisions with charged particles are examples of processes that in principle are inter-related. The probability amplitude second order in the interaction with the incoming charged particle or photon may generally be separated into a real and an imaginary part. The real part contains an energy-conserving propagator and may be regarded classically, while the imaginary part does not conserve energy (in accord with the Uncertainty Principle) and disappears in the limit as ℏ⟶ 0. These two terms are related by a dispersion relation. The energy non-conserving part is the same as the time ordering effect which is a measure of correlation in time. We analyze observations of the ratio of double to single ionization of helium by impact of photons and charged particles.

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