The Scattering and Absorption ofπ+Mesons by Aluminum

Abstract

The interaction of ${\ensuremath{\pi}}^{+}$ mesons with aluminum has been studied in a magnet cloud chamber containing five $\frac{1}{8}$-inch aluminum plates. Meson energies ranged from 25 to 100 Mev. 20 stops, 34 scatters \ensuremath{\ge}30\ifmmode^\circ\else\textdegree\fi{}, and 57 stars were observed. A 1-prong star and a 70-Mev electron-positron pair in coincidence was interpreted as an inelastic charge-exchange scatter. All stops are reasonably accounted for by scatters and stars hidden by the geometry. The cross sections rise steeply with energy. The scattering (elastic plus inelastic) is very roughly isotropic except for a dip in the 60\ifmmode^\circ\else\textdegree\fi{} to 90\ifmmode^\circ\else\textdegree\fi{} interval Corrected absolute cross sections for the 25-45-, 47-70-, and 70-100-Mev intervals, respectively, are $\ensuremath{\sigma}(\mathrm{scat})$, 70\ifmmode\pm\else\textpm\fi{}23, 312\ifmmode\pm\else\textpm\fi{}74, and 216\ifmmode\pm\else\textpm\fi{}82 mb; $\ensuremath{\sigma}(\mathrm{star})$, 176\ifmmode\pm\else\textpm\fi{}34, 299\ifmmode\pm\else\textpm\fi{}62, and 332\ifmmode\pm\else\textpm\fi{}100 mb; and $\ensuremath{\sigma}(\mathrm{total})$, 246\ifmmode\pm\else\textpm\fi{}43, 611\ifmmode\pm\else\textpm\fi{}95, and 548\ifmmode\pm\else\textpm\fi{}129 mb. Detailed results and a description of experimental procedures are given.