Optical electron polarimetry with heavy noble gases.

We have measured the polarization of fluorescence emitted by the noble gases He, Ne, Ar, Kr, and Xe following impact excitation by polarized electrons. In He, the 3P→2S transition was studied; in the heavy noble gases the np(n11)p D3→np(n11)s P2 transitions were analyzed. We investigated these transitions as candidates for efficient optical electron polarimetry and found that, because of their larger excitation cross sections and analyzing power, the heavy noble gases are superior to He, which had been used previously as a polarimetric target. Several issues with regard to the implementation and accuracy of optical electron polarimetric techniques are discussed.