400-Mev Neutron-Proton Scattering

The angular distribution of neutron-proton scattering has been measured at a neutron energy of 400 Mev, with energy resolution of 7 percent. The counter telescope used to detect recoil protons was calibrated in an auxiliary experiment which also gave information about proton-proton scattering at several energies in the 400-Mev region.The n-p cross section has the same general characteristics observed at lower energies, with a minimum at about 100^∘{} (c.m. neutron scattering angle) and a large exchange peak at 180^∘{}. The p-p results indicate an isotropic cross section below 400 Mev, and a rise at small angles at 428 Mev.