π+pInteractions atTπ=450MeV

Elastic and inelastic ${\pi }^{+}p$ interactions at 450 MeV have been studied. The inelastic cross section is (4.3±0.4)% of the total cross section. The ratio of the single-pion production cross sections $\frac{\sigma ({\pi }^{+}p\to {\pi }^{+}{\pi }^{0}p)}{\sigma ({\pi }^{+}p\to {\pi }^{+}{\pi }^{+}n)}$ is 3.5±1.0. Terms up through ${cos}^4{\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ are needed to fit the elastic angular distribution. The effective-mass distributions for ${\pi }^0$ production show (${\pi }^{+}p$) isobar formation and are compared with predictions of the Olsson-Yodh isobar model.