Neutral Meson Photoproduction from Complex Nuclei

Abstract

The angular distributions of neutral mesons produced by 170-MeV bremsstrahlung on carbon, aluminum, copper, cadmium, and lead have been obtained through the coincident detection of the decay photons by a scintillation counter system. The experimental data have been analyzed by means of a Monte Carlo prediction based on an impulse-approximation elastic coherent production model. The nuclear density distributions which were used in the synthesis of those predictions which were in best agreement with the experimental data from this experiment have been compared to the charge density distributions inferred from electron scattering experiments. The values of the rms radii of nuclear matter obtained in this experiment are, within the limits of error of the experiment (about 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}14}$ cm), consistent with the values of charge distribution radii obtained in electron scattering.The spin-independent part of the neutral meson photoproduction cross section used in the synthesized predictions is obtained using the dispersion theory of Chew, Low, Goldberger, and Nambu. The dependence of the cross section on the meson-nucleon phase shifts used is investigated and a set of phase shifts is presented that results in a correct prediction of the absolute cross sections observed in this experiment; however, this particular set of phase shifts is not unique.