Energy distribution of electrons ejected from a thin carbon foil by alpha particles and fission products

Abstract

Abstract. Secondary electron spectra up to 3.5keV electron energy arising from the passage of alpha particles and a52Cf fission products through a 2 gg/cm 2 carbon foil are measured for a forward (42 ~ and a backward (138 ~ angle of emission. The forward spectra induced by alpha-particles are compared to binary encounter calculations and to a gas target spectrum. Systematic differences in the shapes of the alpha particle and the fission product induced spectra are discussed. Total yields and mean energies of the secondary electrons are derived from the spectra.

Energy spectra of secondary electrons ejected by ions from foils

“…Together with the revised transmission value and a lower estimated channeltron efficiency (see next chapter), the absolute cross sections presented here are by factors between 1.2 and 2.0 (compare the present Table 1 with Table 1 of Reference 4) higher than those of [4]. The shape of the spectra in [4] is of course unchanged. -For a typical set-up, the calculation yields a line width (AE/E)FwHM=2.5% and an integral over the line of 1.67 % AE/E.-The resolution was tested with the 24,509 eV conversion-electron line [13] from 2~ For the particular setting used in this case the calculation gave a line width (FWHM) of 1.4 % as compared to the experimental value of 1.65 %.…”

“…These are the correct orders of magnitude to explain the steep increase of the ratio particularly for the gold target above 2 keV electron energy. [4] already showed the data obtained by an integration of the spectra. They have been based on the assumption that the spectra measured under 42 ~ and 138 ~ are representative for the forward and the backward hemisphere, respectively.…”

“…The electrostatic cylinder spectrometer: 1 projectile beam, 2 target foil, 3 fringe field cylinders, 4 entrance slit, 5 electron trajectories, 6 mu-metal shield, 7 outer cylinder, 8 inner cylinder, 9 surface barrier detector, 10 exit slit, 11 channeltron border. The effect of this correction not applied in [4] on the absolute cross section depends on the set-up of the source, the target and the projectile detector. Together with the revised transmission value and a lower estimated channeltron efficiency (see next chapter), the absolute cross sections presented here are by factors between 1.2 and 2.0 (compare the present Table 1 with Table 1 of Reference 4) higher than those of [4].…”

“…The effect of this correction not applied in [4] on the absolute cross section depends on the set-up of the source, the target and the projectile detector. Together with the revised transmission value and a lower estimated channeltron efficiency (see next chapter), the absolute cross sections presented here are by factors between 1.2 and 2.0 (compare the present Table 1 with Table 1 of Reference 4) higher than those of [4]. The shape of the spectra in [4] is of course unchanged.…”

“…In the present work it has been attempted to give a quantitative description of these processes. In a previous publication [4] SE spectra up to 3.5 keV electron energy from a 2 p~g/cm z carbon foil bombarded with e-particles and fission products were discussed and compared to gas target results and Binary Encounter calculations. Principal differences in the shape of SE spectra induced by light ions (e-particles) and by heavy ions (fission products) were found.…”