Measurement of Spin Correlation in Proton-Proton Scattering at 400 and 450 MeV

The spin correlation coefficients $C_{\mathrm{nn}}$ and $C_{\mathrm{KP}}$ for proton-proton scattering have been measured at 400 MeV (60° and 90° in the center-of-mass system) and at 450 MeV (90° in the center-of-mass system) using spark chambers containing carbon plates as the polarization analyzers. At 400 MeV, the results are: $C_{\mathrm{nn}}\left(90\mathrm{}°\right)=0.60\mathrm{}\pm 0.09$, $C_{\mathrm{KP}}\left(90\mathrm{}°\right)=0.32\mathrm{}\pm 0.09$, $C_{\mathrm{nn}}\left(60\mathrm{}°\right)=0.82\mathrm{}\pm 0.47$, and $C_{\mathrm{KP}}\left(60\mathrm{}°\right)=0.60\mathrm{}\pm 0.46$. At 450 MeV, the results are: $C_{\mathrm{nn}}\left(90\mathrm{}°\right)=0.70\mathrm{}\pm 0.15$ and $C_{\mathrm{KP}}\left(90\mathrm{}°\right)=0.37\mathrm{}\pm 0.14$. The results of the 400-MeV measurements are consistent with predicted values for these coefficients obtained by extrapolating the proton-proton phase shifts from lower energies. Phase-shift extrapolations to 450 MeV are not as yet available.