Critical minimum in elastic electron scattering by krypton

Abstract

The position of the critical minimum in elastic electron–krypton scattering at intermediate electron energies was investigated. Differential cross sections (DCSs) were measured as a function of both incident electron energy (100–260 eV) and scattering angle (30–110°), in small steps around the critical minimum. The energy dependence of the angular positions of DCS minima were determined. Also, the positions of minima in energy-dependent DCSs were obtained at several fixed scattering angles close to the critical value. The position of the critical minimum was determined to be at 187.9 ± 0.5 eV and 83.0° ± 0.2°. However, the strong dependence of critical energy on small changes of critical angle was found. The obtained results are compared with the most recent theoretical calculations.

Equivalent of a cartilage tissue for simulations of laser-induced temperature fields

“…This conclusion is based on a detailed experimental investigation of incident beam profile and technical characteristics of the experimental system, according to the work of Brinkmann and Trajmar (1981). Also, it was confirmed by comparing DCSs for Ar and Kr with a number of previous experimental results (see Milosavljević et al (2004aMilosavljević et al ( , 2004b, this work). During the measurements, all the parameters were kept in the range where the contribution of double electron scattering was negligible.…”

“…The energy resolution was about 1 eV, as measured at the FWHM (full-width at half maximum) of the elastic peak. In our previous paper (Milosavljević et al 2004a) it was shown that DCS surface for elastic electron-krypton scattering in this energy range has large energy spread and, in contrast, large gradient along angular axis. Therefore, the main limitation on reaching the deep DCS minima is imposed by finite angular resolution, while in this region the cross sections are rather insensitive to the small changes of incident energy.…”

“…However, as we have chosen the normalization point to be close to the local DCS maxima, the influence of this factor is not significant for the most of the tabulated DCSs. Furthermore, the energy dependence of DCS at the 50 • is rather insensitive to small variations of scattering angle for a wide energy region from about 140 eV to 250 eV (see Milosavljević et al (2004a)). Additionally to the above-discussed errors, a 23% error of absolute cross sections of Cvejanović and Crowe (1997) should also be accounted.…”

“…This should include both angular and energy dependences of DCSs, energy dependence of their angular minima positions and positions of critical points that are defined as local minima on DCS surface (see Milosavljević et al (2004b)). The first detailed experimental investigation of critical minimum in krypton, at intermediate incident energies, has been published very recently by Milosavljević et al (2004a). It was shown that optical potential model calculations of Kelemen (2004) (without absorption) gave much better agreement of the angular and energy positions of the critical minimum with experiment than the improved calculations of McEachran and Stauffer (2003), obtained from the solutions of the relativistic Dirac scattering equation which included absorption as an imaginary part of a complex potential and antisymmetrization to account for exchange effects.…”

Low-energy electron elastic scattering cross sections for excited Au and Pt atoms

“…In the TCSs we identify and delineate the important physical effects such as the Wigner threshold law, Ramsauer-Townsend (RT) minima, shape resonances and BEs of the excited Au À and Pt À anions. The critical minima [26,27] that characterize the DCSs are also extracted from the DCSs and the BEs as well. The TCSs are evaluated using the Mulholland formula [28] implemented through the complex angular momentum (CAM) description of electron-atom scattering while the DCSs are evaluated using a partial wave expansion.…”