Angular Distribution of Protons fromπ−−pScattering at 900 Mev

Abstract

The shape of the ${\pi }^{-}-p$ differential scattering cross section in the backward hemisphere should be sensitive to the nature of the "resonances" assumed to be responsible for the peaks in the total cross section at 600 and 900 Mev. The angular distribution of protons scattered in the forward hemisphere by pions of kinetic energy around 925 Mev, corresponding to pion c.m. angles from 65 deg to 150 deg, was obtained by placing nuclear emulsions close to liquid hydrogen and by measuring the direction angle and the grain count of every proton track. It is shown that the sensitivity of emulsions in the temperature region $22°\mathrm{K}<~T<~90°\mathrm{K}$ does not drop below 85% of the sensitivity at 300°K. The resulting distribution is consistent with the assignment of ${D_{\frac{3}{2}}}^{\frac{1}{2}}$ and ${F_{\frac{5}{2}}}^{\frac{1}{2}}$, respectively, for the 600- and 900-Mev levels.