Electron Scattering by Thin Foils for Energies Below 10 kev

Abstract

The transmission (TIT) of electrons through thin films of C, Al 2 0<j, Al, Ni, Ag, and Au, together with their distribution in angle and energy, were measured in a spherical retarding-potential analyzer. The distributions were characterized by average and most probable scattering angle, average and most probable fractional energy loss, etc. The dependence of these variables on initial energy (E p ), film thickness, and material was investigated. For sufficient film thickness, the transmitted energies, the scattering angles and T]T can be represented as universal functions of the reduced energy, E p /E c , where E c is the critical E p for the onset of transmission. Direct relations exist between TJT, scattering angles, and energy losses for the complete range of scattering from small-angle scattering to total diffusion. The dependence of TJT and average fractional energy loss on Z is consistent with published results on backscattering coefficient and energy loss for thick layers. An estimate of the mean free path for inelastic collisions proves to be in good agreement with the predictions of the Bohr-Bethe theory. Range-energy relations are almost independent of Z when the range is measured in mass per unit area. scribed multiple scattering for small individual deflections, not including any energy loss. The diffusion of high-energy electrons as a result of elastic collisions was treated by Bothe, 3 Bethe, Rose, and Smith 4 and more recently by Moliere. 5 The energy-loss distribution of electrons passing through solids due to inelastic scattering without appreciable deflection has been calculated by Landau, Blunk, and Leisegang, and others. 6 The average rate of energy loss of electrons along their path is well described by Bethe's stopping 3 W.

Geant4‐DNA track‐structure simulations for gold nanoparticles: The importance of electron discrete models in nanometer volumes

“…As part of the Geant4‐DNA collaboration, which provides discrete models to simulate particle track structures in liquid water, we have recently developed new discrete physics models for electron transport in gold (called here Geant4_DNA_AU models) including atomic de‐excitation . Above 10 keV, the new physics models, briefly described in Section 2.A., show agreement with ICRU37 recommended values at the10% level for stopping power and at the 30% level for track length above 500 keV, as well as with experimental data and existing Geant4 condensed‐history models (i.e., Penelope and Livermore transport models). At low energies (below 10 keV), the Geant4_DNA_AU models have a better agreement with experimental measurements of the backscattering coefficient than alternative condensed‐history models included in Geant4 with an improvement of more than 500% compared to Livermore at 30 eV, while providing similar performance for transmission (e.g., a few tens of percent agreement below 5 degrees for 20 MeV electrons for both 9.6 μ m and 19.3 μ m‐thick foils) in macroscopic simulations.…”

An implementation of discrete electron transport models for gold in the Geant4 simulation toolkit

“…Experimental measurements however suggest that the models overestimate the range slightly. [48][49][50][51][52][53] In simulation, we calculate the entire track length of incident electrons, including scattering perpendicular to the incident particle direction, to produce a quantity comparable to the ICRU37 recommended values. Experimental ranges underestimate this value as they do not consider contributions to the path length from scattering perpendicular to the initial particle direction.…”

Response of CsI(Tl) scintillators over a large range in energy and atomic number of ions. Part I: recombination and δ-electrons

“…With R e in mg cm −2 and T in keV, and considering CsI as having an intermediate mean atomic number between those of aluminium and gold, the two extreme media treated in Refs. [51,52], we find the particular value b = 0.016 by keeping n=1.35 [12,51] as universal power index for all the stopping media. Consequently, and without taking into account the angular distribution of the scattered δ -rays, one may estimate the corresponding primary column radius r c .…”