Polarization of the sigma minus hyperon produced by a polarized neutral particle beam.

A spin transfer technique has been tried in an attempt to produce a beam of polarized hyperons. The method makes use of a two-stage targeting scheme where unpolarized protons from Fermilab's Tevatron incident on target number one (Cu) at production angles of $\pm$2.0 mrad would produce a beam of particles containing polarized $\Lambda$s and $\Xi$s as well as neutrons and Ks. This secondary beam would then be swept magnetically to retain only neutral particles and brought to bear on target number two (Cu) at 0.0 mrad, producing a tertiary beam of hyperons. The polarization of some 1.3 millions reconstructed $\Sigma\sp{-} \to$ n$\pi\sp{-}$ events in this tertiary beam (the $\Sigma\sp{-}$ having been produced in the inclusive reaction neutrals + $Cu \to \Sigma\sp{-} + X)$ has been measured at average $\Sigma\sp{-}$ momenta 320 GeV/c (1.14 millions events) and 410 GeV/c (135,000 events) and found to be $\vert$P$\vert$ = 3.9 $\pm$ 3.2 $\pm$ 1.8% and $\vert$P$\vert$ = 13.9 $\pm$ 8.1 $\pm$ 2.0% respectively, where the first uncertainty is statistical and the second systematic. These polarizations are small and consistent with zero, and preclude a meaningful measurement of the $\Sigma\sp{-}$ magnetic moment by the spin precession method. The sign of the polarizations at the target is ambiguous, giving rise to two possible different solutions for the magnetic moment--one of which distinctly disagrees with the world average value for the moment. However, this solution fits the data slightly better than the other. This inconsistency would not exist if the polarization is, in fact, zero.PhDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102961/1/9226973.pdfDescription of 9226973.pdf : Restricted to UM users only