High-efficiency retarding-potential Mott polarization analyzer

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Abstract
A compact retarding-potential Mott polarimeter is described that employs a thorium target. When operating at an electron accelerating voltage of 25 kV, the instrument provides effective asymmetry (Sherman) functions Seff between −0.15 and −0.25, the exact value being determined by the inelastic energy loss window selected. The corresponding scattering efficiencies I/I0 are in the range ∼6–2×10−3 resulting in optimized efficiencies η (≡S2effI/I0) of ∼1.6×10−4. These efficiencies are much larger than have been obtained previously with similar analyzers. The instrument is simple to construct, is stable in operation, and has a large electron-optical acceptance, estimated to be ∼104 mm2 sr eV. It is fully UHV compatible and is suitable for application in a wide range of spin-dependent studies.