Characterization of a Compact Cylindrically Symmetric Micro-Mott Polarimeter

A Mott polarimeter measures electron spin by determining the left-right counting rate asymmetry, $A$, for Mott scattering from a high-Z target. This value of $A$ is non-zero for spin states perpendicular to the electron scattering plane. Recently, a variety of small, spherically symmetric polarimeters of the ``concentric'' electrode design using energies of $\sim$ 20 keV have been designed and constructed [1]. The geometry of these polarimeters causes inelastic scattering events to be largely eliminated electrostatically which results in a resolution higher than that obtainable with energy-sensitive detectors alone [2]. A small quasi-cylindrically-symmetric polarimeter, simpler in conception and construction than its spherical counterparts, has been designed and built [3]. Using a new negative electron affinity GaAs polarized electron source, this compact Mott polarimeter's efficiency has been determined and its Sherman function has been estimated. \\[4pt] [1] T. J. Gay, Adv. At. Mol. Phys. \textbf{57}, 227-232 (2009).\\[0pt] [2] G. D. Fletcher, T. J. Gay and M. S. Lubell, Phys. Rev. A \textbf{34}, 911 (1986).\\[0pt] [3] G. H. Rutherford, R. M. King, G. G. Shepard, M. S. Zimmerle, Bull. Am. Phys. Soc. \textbf{44} (1999).