Spin-Spin Forces in 6-GeV/<i>c</i>Neutron-Proton Elastic Scattering

Abstract

Measurement was made of $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ for ${n}_{\ensuremath{\uparrow}}+{p}_{\ensuremath{\uparrow}}\ensuremath{\rightarrow}n+p$ at ${{P}_{\ensuremath{\perp}}}^{2}=0.8 \mathrm{and} 1.0$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ at 6 GeV/c. The 6-GeV/c 53%-polarized neutrons from the 12-GeV/c polarized deuteron beam at the Argonne zero-gradient synchroton were scattered from our 75%-polarized proton target. Both spins were oriented perpendicular to the scattering plane. We found large unexpected spin-spin effects in $n\ensuremath{-}p$ elastic scattering which are quite different from the $p\ensuremath{-}p$ spin-spin effects.