Neutron-Proton Forward-Angle Elastic Cross Sections at 790 MeV

High-statistics measurements of the absolute differential cross section for $n-p$ scattering have been made over neutron c.m.-system scattering angles $9.5°<{\theta }^{*}<64.5\mathrm{}°$. The statistical error is 1.7 to 3.3% for 2°-wide angular bins, and the systematic error is 2.7 to 3.3%. The cross section is fitted by $\frac{d\sigma }{d{\Omega }^{*}}=A \exp \mathrm{}\left(\mathrm{bt}\right)\mathrm{}$, with $A=10.27\mathrm{}\pm 0.36$ mb/sr, $b=5.00\mathrm{}\pm 0.05$, and $0.01<-t<\mathrm{}0.39\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. For the ratio of the real to the imaginary part of the forward-scattering amplitude we obtained ${\alpha }_n>~-0.43\mathrm{}\pm 0.04$, consistent with other less precise determinations of ${\alpha }_n$.