Measurement of cross sections and asymmetry parameters for the production of charged pions from various nuclei by 585-MeV protons

We have measured the differential cross section $\frac{d^2\sigma }{d\Omega d{T}_{\pi }}$ and the polarization parameter $P$ for the production of ${\pi }^{+}$ and ${\pi }^{-}$ in various target nuclei (${}_{}{}^1{}_{}{}^{}\mathrm{H}$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, Be, C, O, Al, Ni, Cu, Mo, and Pb) by protons with a kinetic energy of 585 MeV, for production angles ${\theta }_{\pi }=22.5\mathrm{}°, 45°, 60°, 90°, \mathrm{and} 135°$, and for pion kinetic energies $T_{\pi }$ of 24, 35, 46, 88, 151, 192, and 254 MeV (all quantities in the laboratory system). Our data disagree strongly with recent data for 580-MeV protons. On the other hand, for pion energies up to 150 MeV, our cross sections differ little from those measured for a proton energy of 730 MeV. For nuclei with $A>\mathrm{}20\mathrm{}$, the total production cross sections $\sigma \left({\pi }^{+}\right)$ and $\sigma \left({\pi }^{-}\right)$ show the $Z^{\frac{1}{3}}$ and $N^{\frac{2}{3}}$ proportionality expected from theoretical arguments. There is evidence in our data of a shift of the ${\pi }^{+}$ energy distributions compared to the ${\pi }^{-}$ distributions due to the effects of the Coulomb field of the nuclear protons on the emitted pions.