Monte Carlo simulation of bremsstrahlung emission by electrons

Abstract

An algorithm for the simulation of bremsstrahlung emission by fast electrons using numerical cross sections is described. It is based on natural factorization of the double-differential cross section and on the fact that the intrinsic angular distribution of photons with a given energy can be very closely approximated by a Lorentz-boosted dipole distribution. The parameters of this angular distribution vary smoothly with the atomic number of the target atom and with the energies of the projectile’s electron and the photon emitted. Results from simulations of thick-target bremsstrahlung are compared with experimental data.

Monte Carlo simulation of x-ray spectra generated by kilo-electron-volt electrons

“…14 To be more specific, we consider the bremsstrahlung DCS for electrons of kinetic energy E in an amorphous, single-element medium of atomic number Z. After integrating over the angular deflection of the projectile, the DCS depends only on the energy W of the emitted photon and on the direction of emission, represented by the polar angle relative to the direction of the projectile, and can be expressed as…”

“…In the present article we describe an MC algorithm for the simulation of x-ray spectra emitted from targets bombarded by keV electrons, which incorporates the Acosta et al 14 simulation of bremsstrahlung emission together with K-and L-shell ionization cross sections obtained from the DWBA calculations of Segui et al. 17 The relaxation of ionized atoms is simulated by using transition probabilities from the Lawrence Livermore National Laboratory Evaluated Atomic Data Library ͑EADL͒.…”

“…Recently, Acosta et al 14 have proposed an algorithm for the simulation of bremsstrahlung emission in which ͑i͒ the energy of emitted photons is sampled from numerical energy-loss spectra obtained from the scaled cross-section tables of Seltzer and Berger 15 and ͑ii͒ the angular distribution is described by an analytical expression with parameters determined by fitting the benchmark partial-wave shape functions of Kissel, Quarles and Pratt. 16 Segui et al, 17 on the other hand, have developed a computer code for calculating electron-impact ionization cross sections of neutral atoms using the distorted-wave Born approximation ͑DWBA͒.…”

Cross sections for electron interactions in condensed matter

“…These authors also provide a parameterisation of the shape function in terms of Legendre polynomials, which is not well suited for random sampling of the photon direction. Very recently, Acosta et al 63 proposed a more convenient parameterisation of the shape functions, which fully accounts for the correlations between Ä and Â. The method consists of expressing p Z, E, Ä; cos  as an admixture of two Lorentz-boosted dipole distributions, whose parameters vary continuously with E and Ä.…”

PENEPMA: a Monte Carlo programme for the simulation of X-ray emission in EPMA

“…A global renormalisation is also applied to the cross-sections of outer subshells to ensure that the collision stopping power remains unaltered. The energy of bremsstrahlung photons is sampled from numerical energy-loss spectra derived from the scaled cross-section tables of Seltzer and Berger [12], while the angular distribution of radiated quanta is described by an analytical expression consisting of an admixture of two "boosted" dipole distributions [13], with parameters determined by fitting the benchmark partial-wave shape functions of Kissel, Quarles and Pratt [14].…”