A calibration of the IUCF K600 focal plane polarimeter

We have carried out a precise determination of the effective analyzing power of the K600 focal plane polarimeter at IUCF for incident proton energies extending from 200 MeV down to 120 MeV. Two different calibration techniques, and several analyzer thicknesses, were used over this range. As the energy decreases, the effective analyzing power falls almost linearly. The polarimeter efficiency, however, rises rapidly, thus maintaining a reasonable figure‐of‐merit.