Coplanar symmetric (e, 2e) results are presented for the ionization of calcium by electron impact. The incident electron energy was varied from 10.1 to 64.6 eV, the outgoing electrons sharing the excess energy equally. The experimental results show a complex variation in the magnitude of the cross-section as a function of energy and angle. At the highest incident energy, the cross-section varies by almost five orders of magnitude. At the lowest energy, evidence of post-collisional interaction between the outgoing electrons can be seen, although the magnitude of this effect is small. S This article has associated online supplementary data files

Using a low-resolution electron-impact spectrometer in excitation function mode, the energy dependence of differential cross sections for elastic scattering of electrons on argon and krypton was studied. Relative cross sections were put on an absolute scale by normalizing to the previous data of Srivastava et al at one conveniently chosen energy and angle in each gas. Differential cross sections for elastic scattering of electrons on krypton are compared with previously published cross sections for positron scattering. No broad resonance-like structures are observed in the case of electron scattering but the energy dependence, especially in krypton, shows a strong variation with energy which is not observed for positrons.

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Excitation of the 31P state of magnesium by 40 eV electrons has been studied experimentally using the polarized photon-scattered electron correlation method over a wide range of scattering angles (10°–120°). Measured Stokes parameters are consistent with the small angle (≤20°) data of Brunger et al (1989 J. Phys. B: At. Mol. Opt. Phys. 22 1431–32). The measured linear Stokes parameters, and the circular polarization calculated from these parameters, assuming coherent excitation, are generally well produced by recent theoretical models, convergent close coupling, R-matrix with pseudo states, relativistic distorted wave and first-order many-body theory. Despite extensive testing, directly measured circular polarization data yielded low values at most scattering angles beyond 20°. Differential cross sections for elastic scattering and excitation of the 31P and 33P states were also measured over the angular range 10°–140° and compared with theoretical predictions.

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