Extrapolation procedures in Mott electron polarimetry

Authors

Timothy J. Gay, University of Nebraska - LincolnFollow
M. A. Khakoo, University of Missouri-Rolla, Rolla, Missouri
J. A. Brand, University of Missouri-Rolla, Rolla, Missouri
J. E. Furst, University of Missouri-Rolla, Rolla, Missouri
W. V. Meyer, University of Missouri-Rolla, Rolla, Missouri
W. M. K. P. Wijayaratna, University of Missouri-Rolla, Rolla, Missouri
F. B. Dunning, Rice Quantum Institute, Rice University, Houston, Texas

Date of this Version

January 1992

Comments

Published in Rev. Sci. Instrum. 63 (l), January 1992. Copyright 1992 American Institute of Physics. Used by permission.

Abstract

In standard Mott electron polarimetry using thin gold film targets, extrapolation procedures must be used to reduce the experimentally measured asymmetries A to the values they would have for scattering from single atoms. These extrapolations involve the dependence of A on either the gold film thickness t or the maximum detected electron energy loss in the target ΔE. Using a concentric cylindrical-electrode Mott polarimeter, we have studied and compared these two types of extrapolations over the electron energy range 20-100 keV. The potential systematic errors which can result from such procedures are analyzed in detail, particularly with regard to the use of various fitting functions in thickness extrapolations, and the failure of perfect energy-loss discrimination to yield accurate polarizations when thick foils are used. A critical discussion of previous work on this subject is presented.