Calculation of the electron electron bremsstrahlung crosssection in the field of atomic electrons
Abstract
An accurate expression for the free electronelectron bremsstrahlung (eebrems) crosssection was derived by Haug in 1975, but unfortunately it must be combined with a rather prosaic correction to account for electron binding in atoms. We report on a numerical calculation of the eebrems crosssection which include the effect of binding explicitly from the outset. Electronelectron bremsstrahlung occurs when a photon is emitted during the collision of two electrons, and an accurate treatment of eebrems is welladvised in light elements, where it is significant compared to the nuclear bremsstrahlung process dominating in heavier elements. Our calculation allows us to verify and refine the eebrems crosssection calculation recommended as part of ICRU Report 37. The results are auspicious in that they confirm the validity of the recommended approximations for electrons with high incident energies and over most of the emitted photon energy range. For incident energies on the order of 1 MeV or lower, however, we find a considerable discrepancy between the eebrems radiative crosssection obtained with the ICRU calculation and with our more accurate approach. Accordingly, we correct existing crosssection data tables for the EGSnrc radiation transport simulation software.
 Publication:

Nuclear Instruments and Methods in Physics Research B
 Pub Date:
 February 2008
 DOI:
 10.1016/j.nimb.2007.11.063
 Bibcode:
 2008NIMPB.266..625T
 Keywords:

 Electronelectron bremsstrahlung;
 Crosssection;
 Softphoton limit;
 34.80.i;
 34.50.Bw;
 95.30.Jx;
 Electron scattering;
 Energy loss and stopping power;
 Radiative transfer;
 scattering