A Comparison of Sona and Spin-Filter Polarization Schemes for a Lamb-Shift Polarized Ion Source

Presently operating Lamb-shift polarized ion sources use either the Sona or the spin-filter polarization method. The University of Washington Lambshift source operated according to the Sona (diabatic field-reversal) method until late 1976. At that time we installed a spin-filter system and associated apparatus required to implement the rapid spin-reversal system of McKibben and Potter.1 This conversion was motivated by a desire to reduce systematic errors in analyzing-power measurements below the 10-4 level achieved with the Sona scheme. This is of importance in our continuing efforts to measure parity-violating effects in 19F and in other ongoing experiments. We report here a comparison of the performance of these two ion-source versions and construction costs of the spin-filter system. We also compare spin-correlated beam motion for the two systems. We find that the benefits associated with the spin-filter installation are well worth the cost.