Angular distributions of the differential cross section and analyzing power for the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(p,${\pi }^{+}$${)}^4$He have been measured at $T_{\mathrm{p}=178\mathrm{}}$ and 198 MeV. The analyzing powers, which have not been measured previously in the near threshold region, are similar to those of the elementary pp→${\pi }^{+}$d reaction at low energies reflecting the dominance of the two-nucleon reaction mechanism.

• Received 30 September 1985

DOI:https://doi.org/10.1103/PhysRevC.33.725