Charge-Exchange Scattering of Negative Pions at 61 Mev and 95 Mev

Abstract

The charge-exchange scattering of negative pions by liquid hydrogen has been measured at 61\ifmmode\pm\else\textpm\fi{}1 Mev and 95\ifmmode\pm\else\textpm\fi{}2 Mev bombarding energy. The measurements were made with a gamma-ray spectrometer which employs a lead glass \ifmmode \check{C}\else \v{C}\fi{}erenkov counter. If the charge exchange scattering cross section is expanded as a series of Legendre polynomials in the center-of-mass system of the collision, we find that at 61 Mev, $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=(1.00\ifmmode\pm\else\textpm\fi{}0.05)[0.613\ifmmode\pm\else\textpm\fi{}0.030\ensuremath{-}(0.830\ifmmode\pm\else\textpm\fi{}0.068){P}_{1}({cos\ensuremath{\theta}}^{\ensuremath{'}})+(0.183\ifmmode\pm\else\textpm\fi{}0.150){P}_{2}({cos\ensuremath{\theta}}^{\ensuremath{'}})],$ and at 95 Mev, $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=(1.00\ifmmode\pm\else\textpm\fi{}0.03)[1.05\ifmmode\pm\else\textpm\fi{}0.05\ensuremath{-}(1.15\ifmmode\pm\else\textpm\fi{}0.12){P}_{1}({cos\ensuremath{\theta}}^{\ensuremath{'}})+(0.33\ifmmode\pm\else\textpm\fi{}0.25){P}_{2}({cos\ensuremath{\theta}}^{\ensuremath{'}})].$ The total cross section for charge exchange, obtained by integration, is: ${\ensuremath{\sigma}}_{\mathrm{tot}}({\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0})=7.7\ifmmode\pm\else\textpm\fi{}0.6$ mb at 61 Mev and ${\ensuremath{\sigma}}_{\mathrm{tot}}({\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0})=13.2\ifmmode\pm\else\textpm\fi{}0.8$ mb at 95 Mev.A table summarizing the measurements performed by this group at 61 Mev, 95 Mev, 128 Mev, and 150 Mev is given.