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 d/sup 2/sigma/d..cap omega..dT/sub ..pi../ and the polarization parameter P for the production of ..pi../sup +/ and ..pi../sup -/ in various target nuclei (/sup 1/H, /sup 2/H, Be, C, O, A1, Ni, Cu, Mo, and Pb) by protons with a kinetic energy of 585 MeV, for production angles theta/sub ..pi../=22.5/sup 0/, 45/sup 0/, 60/sup 0/, 90/sup 0/, and 135/sup 0/, and for pion kinetic energies T/sub ..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 > 20, the total production cross sections sigma(..pi../sup +/) and sigma(..pi../sup -/) show the Z1/sub /3/ and N2/sub /3/ proportionality expected from theoretical arguments. There is evidence in our data of a shift of the ..pi../sup +/ energy distributions compared to the ..pi../sup -/ distributions due to the effects of the Coulomb field of the nuclear protons on the emitted pions.