Toward precision polarimetry of dense polarized 3He targets

We describe several new measurement and analysis techniques used to determine the polarization of the 3He target in a recently completed measurement of the neutron spin structure function g1n at SLAC (E-154). The polarization was determined using two independent methods. The first method used a standard technique of Adiabatic Fast Passage, calibrated by a measurement of Boltzmann polarization in a sample of water. We describe several systematic effects affecting this calibration procedure. The second method used a shift of the Rb Zeeman resonance frequency due to the polarization of 3He. Implementation and calibration of this technique are discussed in detail. Finally, the density of 3He in the cell was measured using two independent methods, one of them based on the pressure broadening of Rb D1 and D2 lines due to 3He.