HIGH-EFFICIENCY RETARDING-POTENTIAL MOTT POLARIZATION ANALYZER

A compact retarding-potential Mott polarimeter is described that emplo ys a thorium target. When operating at an electron accelerating voltag e of 25 kV, the instrument provides effective asymmetry (Sherman) func tions S(eff) between -0.15 and -0.25, the exact value being determined by the inelastic energy loss window selected. The corresponding scatt ering efficiencies I/I0 are in the range approximately 6-2 x 10(-3) re sulting in optimized efficiencies eta(S(eff)2I/I0) of approximately 1. 6 x 10(-4). These efficiencies are much larger than have been obtained previously with similar analyzers. The instrument is simple to constr uct, is stable in operation, and has a large electron-optical acceptan ce, estimated to be approximately 10(4) mm2 sr eV. It is fully UHV com patible and is suitable for application in a wide range of spin-depend ent studies.