Design and construction of a high efficiency retarding potential Mott polarization analyzer

Abstract

New insights into many physical phenomena can be obtained through spin dependent analysis and such investigations frequently require an electron spin polarimeter. In the past available polarimeters have been bulky and required very high voltages (100 kV or more) in order to operate. In recent years more portable models which operate in the 20 kV range have been constructed with efficiencies (figures of merit) of $3\times 10\sp{-5}$. A very compact UHV compatible retarding potential Mott polarimeter is described here that provides the highest efficiencies yet achieved with an instrument of this type. With a thorium target and electron accelerating voltage of 25 kV, it provides effective Sherman functions $\rm S\sb{eff}$ between $-$0.15 and $-$0.25. The resulting figures of merit are as high as $\approx1.6\times 10\sp{-4}$ which make the device attractive for use in any application requiring electron spin polarimetry.