We have performed proton inclusive scattering measurements at 500 MeV on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, Ni, and Ta at angles at 65°, 90°, 120°, and 160°. Analyzing powers were also obtained for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and Ni. The data extend in energy to the elastic scattering peak for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at 90°. The cross-section data are described well by a direct knockout model and by quasi-two-body scaling calculations. Fits to analyzing power results by these theories are poor, and furthermore, we find a qualitative difference between the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and Ni results. The Ni data show large positive analyzing powers at high detected particle energies, in keeping with results obtained on various targets from ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ to ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ at 800 MeV bombarding energy; the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ analyzing powers are predominantly negative or close to zero.

NUCLEAR REACTIONS Proton inclusive scattering; ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, Ni, ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$; $E=500\mathrm{}$ MeV; measured $\sigma \left(E_p\right)$, $P\left(E_p\right)$.

• Received 26 August 1980

DOI:https://doi.org/10.1103/PhysRevC.23.1671