A cylindrically symmetric “micro-Mott” electron polarimeter

Abstract

A small, novel, cylindrically symmetric Mott electron polarimeter is described. The effective Sherman function, Seff, or analyzing power, for 20 kV Au target bias with a 1.3 keV energy loss window is 0.16 ± 0.01, where uncertainty in the measurement is due primarily to uncertainty in the incident electron polarization. For an energy loss window of 0.5 keV, Seff reaches its maximum value of 0.24 ± 0.02. The device's maximum efficiency, I/Io, defined as the detected count rate divided by the incident particle rate, is 3.7 ± 0.2 × 10(-4) at 20 keV. The figure-of-merit of the device, η, is defined as Seff (2)IIo and equals 9.0 ± 1.6 × 10(-6). Potential sources of false asymmetries due to detector electronic asymmetry and beam misalignment have been investigated. The new polarimeter's performance is compared to published results for similar compact retarding-field Mott polarimeters, and it is concluded that this device has a relatively large Seff and low efficiency. SIMION(®) electron trajectory simulations and Sherman function calculations are presented to explain the differences in performance between this device and previous designs. This design has an Seff that is insensitive to spatial beam fluctuations and, for an energy loss window>0.5 keV, negligible background due to spurious ion and X-ray production at the target.

Partially coherent quantum degenerate electron matter waves

“… using equation ( 18) instead. This shows a reduction in the contrast by a factor of 3 compared with a similar but polarized beam and identifies a measurable control for the fermionic HBT experiments using controllable ultrafast spin-polarized pulsed electron sources [24]. For pulse c…”

Femtosecond-laser-induced spin-polarized electron emission from a GaAs tip

“…We also measured the total emission current from the electrically-isolated sample. Emitted electrons were directed to a compact, cylindrical Mott polarimeter, 34 comprising two concentric cylindrical electrodes and two CEMs placed symmetrically about the entrance that defined the electron scattering plane. The central gold-plated electrode was biased at +20 kV, whereas the outer electrode and the mouths of the CEMs were biased at +500 V.…”