Excitation Function for Charged π -Meson Production in Hydrogen and Carbon by 345- to 380-Mev Protons

The 90^∘{} differential cross section for charged meson production in hydrogen and carbon is measured for incident proton energies 345 to 380 Mev. For hydrogen, the 90^∘{} π⁺} meson production energy spectra occur as peaks in the energy region predicted from the kinematics of the reaction p+p→π⁺+d. Ratios of these 90^∘{} π⁺ differential cross sections are (dσ)(dω) at 380 Mev: (dσ)(dω) at 365 Mev: (dσ)(dω) at 345 Mev=2.6:1.6:1 with a statistical uncertainty of 15 percent. For carbon the π⁺ meson production spectra show an increase in the energy of the maximum of the broad distributions, with increasing incident proton energy. The (π⁺)(π^-) ratio in carbon is found to be in the range (10±{}3): 1 for all three proton energies studies. Qualitative agreement with these carbon π⁺ meson spectra is obtained from a phenomenological analysis based upon the assumptions of nucleon-nucleon collisions in which the target has a Gaussian momentum distribution.