Effects of quadrupole focusing on HRS focal-plane polarimeter measurements

The leading effect of the High Resolution Proton Spectrometer (HRS) on scattered-particle polarizations is a precession corresponding to the approximately 1500 bend that is caused by the HRS dipole fields. There are, however, other small bends of the particles' trajectories due to focusing caused by the HRS quadrupole and dipoles. The precession angles corresponding to these bends are much smaller than that due to the 1500 bend; nevertheless, for high-accuracy measurements of scattered-particle polarizations, these effects can be significant. These small bends give rise to differential corrections within the acceptance of the spectrometer. This report is concerned with the calculation of these effects on the measurement of the polarization-transfer (PT) observables and the induced polarization