Measurement of the Mott Asymmetry in Double Scattering of Electrons

Abstract

The Mott asymmetry was observed at 121 kev for gold targets and scattering angles of 0i = 9O° and 02 = 80° to 140°. The cosine dependence of the asymmetry on the azimuthal angle was shown in all cases. A weak magnetic lens (maximum field: 12.5 gauss) was used between the two scatterers, and a low-resolution (8%) electrostatic energy analyzer was used after second scattering. The measured asymmetry amplitudes are compared with the calculations of Sherman (pure Coulomb field) and of Mohr and Tassie (screened Coulomb field). The experimental values for 0 2 = 9O°, 100°, 110° agree well with either theoretical curve but are not accurate enough to distinguish between them. The measured value at 0 2 = 8O° is enough higher (17%) than the pure Coulomb field curve to indicate a screening eifect. The experimental values for 0 2 = 120°, 130°, and 140° fall from 15% to 20% below the theoretical curves. This discrepancy is attributed to plural scattering. Measurements made using the magnetic lens but not the energy analyzer yield asymmetries reduced in amplitude about 33% and shifted in phase by 26° when compared with the measurements discussed above. This is believed due to the presence of an appreciable number of polarized electrons at a considerably lower energy than 121 kev in the first scattered beam.

Spin and angle resolved photoemission on non-magnetic low-dimensional systems

“…Currently there are two primary detection schemes that successfully manage to do this, but both have their (dis)advantages. The first detection scheme is the conventional or classical Mott polarimeter [18] where the electrons are accelerated between two concentric hemispheres to 40-60 kV. The gold foil and the detectors (typically passivated implanted planar silicon (PIPS)) are at the same potential inside the inner hemisphere and the electrons thus travel through field free space between the foil and the detector [19].…”

Elastic scattering of relativistic electrons by screened atomic nuclei

“…The series (13) and (14) are summed with the usual computer precision (8 significant figures) up to the terms where the variation in S(O) contributed by the last thirty terms is less than 1%. To check this summation method, we made the following tests: a) For two cases, the series (13) and (14) are summed using double precision (16 digit numbers). The P~(cos 0) and Ptt(cos 0) polynomials were also generated from the recursion relation by the double precision method.…”

“…Eqs. (13) and 14were summed until the variation in S(O) due to the last thirty terms was less than 1%. The polynomials P~ and P~ are generated from the recursion relations.…”

New compact classical 40 kV Mott polarimeter

“…1,2 There is the wide spectrum of different kinds of Mott polarimeters. [3][4][5][6][7][8][9] Other types of polarimeters are not discussed here because they are not real competitors to Mott detectors for numerous parameters. In this article we describe a new classical polarimeter built in the Surface Magnetism Group at St. Petersburg Technical University based on the experience and equipment held in our team.…”