A small, novel, cylindrically symmetric Mott electron polarimeter is described. The effective Sherman function, S eff , 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, S eff reaches its maximum value of 0.24 ± 0.02. The device's maximum efficiency, I/I o , defined as the detected count rate divided by the

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... incident particle rate, is 3.7 ± 0.2 × 10 −4 at 20 keV. The figure-of-merit of the device, η, is defined as S 2 eff I I o 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 S eff 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 S eff 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. Published by AIP Publishing. [http://dx.