Neutron-Proton Elastic Scattering from 2 to 7 GeV/c

Direct measurements were made of neutron-proton elastic scattering differential cross sections at high energies. A neutron beam with a continuous momentum spectrum between 1.2 and 6.7 GeV/c was scattered off a liquid hydrogen target, and spark chambers were used to determine the neutron scattering angle and, in a proton spectrometer, to measure the momentum and scattering angle of the recoil proton. Differential cross sections are presented over the incident neutron momentum range in intervals of the order of 0.5-GeV/c wide. The cross sections have an exponential peak in the forward direction and then flatten and become isotropic about the 90° c.m. scattering angle. At larger angles, the cross sections again rise towards the expected charge-exchange peak, which was not within the range of this experiment. There is little evidence of any other structure in the cross section. Values are presented for the slope of the diffraction peak, and comparisons are made between these slopes, and the 90° c.m. cross sections, for $\mathrm{pp}$ and $\mathrm{np}$ elastic scattering. The results presented here differ from those previously reported because of an error in a Monte Carlo calculation and in the availability of improved data on the real part of the $\mathrm{np}$ elastic scattering amplitude. At 5 GeV/c, a direct comparison of $\mathrm{pp}$ and $\mathrm{np}$ data allows the $I=0\mathrm{}$ differential cross section to be extracted. The $\mathrm{np}$ data have been fitted in powers of ${cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ for $\left|{cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right|<\mathrm{}0.8\mathrm{}$ for each energy range.