Angular correlation, electron-photon

Figure 5.32 Angular correlation between 4d5/2 photo- and N5-02> 302f 3 Sq Auger electrons in xenon. A polar plot of the coincident intensity is shown for the following experimental conditions photon energy 94.5 eV, Stokes parameter Sj = 0.957, S2 = 0, S3 unknown both electrons are detected in a plane perpendicular to the incident photon beam, the photoelectron at fixed position (ephe) with 0 = 90°, = 150°, the Auger electron at...

If there is more than one particle emitted in the scattering process, and one or more of these (electron, photon, etc.) are detected in coincidence with the scattered electron, then the cross sections are also differential with respect to the energy and angular distributions of these secondary particles. Such measurements are called correlation measurements, since the cross section depends on the correlation between say the angles (or energies, or spin directions) of the final particles. 

Electron—photon coincidences — angular and polarisation correlations... 

The angular correlation PAS measurement is based on the evaluation of the 511 keV y-photon distribution. The total momentum of both y photons arising during the moment of annihilation is equal to the momentum of the annihilated (e+, e ) pair. Because the is thermalised before the annihilation in the material, its momentum can be neglected. Therefore, the angular distribution of the y-photon pairs depends on the local electron momentum distribution in the observed material. This fact is frequently used in the study of mechanical, thermal or radiation-induced defects in materials [131]. 

In order to excite atomic magnetic sub-levels with 0 it is necessary to detect electrons outside of the forward direction. Information about those magnetic sub-levels can be obtained by investigating the angular correlations between electrons scattered inelastically from an atom and the photon emitted in the scattering plane. Such a study commenced in 1968 to investigate the excitation of the 2 P state of helixom and the first results were reported by Eminyan et al in 1973. 

It is still necessary to perform the measurements at two different scattering geometries. Angular correlation functions were measured for photon azimuthal angles of (j) = tt (in the electron... 

The position and angular trajectory of an electron, and hence of the emitted photons, are correlated parameters. The phase space plot relates the position (x or y) of an electron and its angular trajectory (x or y )... 

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