| Popis: |
The total and differential cross section for the scattering of 217-Mev positive pions on hydrogen has been measured in nuclear emulsions. The total cross section, excepting Coulomb scattering, was found to be (151.0\ifmmode\pm\else\textpm\fi{}18.2) mb. The angular distribution in the center of mass was fitted by $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=(5.22\ifmmode\pm\else\textpm\fi{}1.42)+(7.53\ifmmode\pm\else\textpm\fi{}2.57)cos\ensuremath{\chi}+(20.36\ifmmode\pm\else\textpm\fi{}4.61){cos}^{2}\ensuremath{\chi}$ mb/steradian, assuming $S$ and $P$ waves only. A phase shift analysis was carried out using the method of maximum likelihood. The phase-shift solution in agreement with the requirements of causality and corresponding to the preferred solution of de Hoffman et al. was ${\ensuremath{\alpha}}_{3}=\ensuremath{-}22.5\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}5.8\ifmmode^\circ\else\textdegree\fi{}$, ${\ensuremath{\alpha}}_{33}=114.0\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}7.4\ifmmode^\circ\else\textdegree\fi{}$, and ${\ensuremath{\alpha}}_{31}=\ensuremath{-}11.6\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}9.7\ifmmode^\circ\else\textdegree\fi{}$. The angular distribution showed strong forward scattering and a perference for positive Coulomb interference, in agreement with the hypothesis of a resonance in the state with angular momentum $\frac{3}{2}$ and isotopic spin $\frac{3}{2}$. |
