Parametrization ofσtot,σ(θ), andP(θ)for 25-100 MeVnpelastic scattering

We present a parametrization of the ${}_{}{}^1{}_{}{}^{}\mathrm{H}(n,n){}_{}{}^1{}_{}{}^{}\mathrm{H}$ total cross section, differential cross section, and polarization, for the neutron lab kinetic energy range 25-100 MeV. The observables we parametrized are computed from the phase shifts of the Bryan-Gersten potential-model constrained fit to all of the available 0-450 MeV $np$ and $pp$ elastic scattering data. We find our parametrization of $\sigma \left(\theta \right)$ to differ significantly from the Gammel formula, in that for all energies 25-100 MeV we have higher $\frac{\sigma \left(180\mathrm{}°\right)}{\sigma \left(90\mathrm{}°\right)}$ ratios, as well as $\sigma \left(\theta \right)$ shapes which are nonsymmetric about 90° c.m. Our total cross sections begin to differ from the Gammel formula at neutron energies above 50 MeV, where the Gammel formula was never meant to apply anyway.