Asymmetries Ay for π+ and π- elastic scattering from polarized 3He were measured at incident energies passing through the π nucleon P33, or Δ (1232), resonance. The data were taken at the Clinton P. Anderson Meson Physics Facility using the high-energy pion channel P3 and a large acceptance spectrometer to detect the scattered pions. The polarized 3He target, originally developed at TRIUMF, was modified tor these experiments by the addition of diode lasers. Completely unexpected negative asymmetries were observed at and below the resonance in π+ scattering near 50°-60°, which cannot be reproduced by multiple scattering theory and Faddeev wave functions. A hybrid model, which adds a Δ-neutron spin-spin interaction term to the conventional calculations, provides a good description of the π+ data. For π- scattering this term predicts a negligible effect on Ay and the data do not show the anomalous Ay seen with π+.
|Number of pages||14|
|Journal||Physical Review C - Nuclear Physics|
|Publication status||Published - 1997 Nov|
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Nuclear and High Energy Physics