Phase-shift analysis of the 20-30-MeV $\mathrm{pp}$ and $\mathrm{np}$ scattering data, including new high-precision $\mathrm{np} P\left(\theta \right)$ measurements

The available $\mathrm{pp}$ and $\mathrm{np}$ scattering data in the energy range 20-30 MeV are analyzed and reduced in order to obtain a minimum set without loss of statistically significant information. The new Jones-Brooks and Morris-O'Malley-May-Thornton high-precision $\mathrm{np} p\left(\theta \right)$ data are included. The resulting set of 43 $\mathrm{pp}$ and 65 $\mathrm{np}$ independent data are augmented by Coulomb splittings of the $\mathrm{pp}$ and $\mathrm{np}$ isospin-one phase shifts and by high and intermediate angular momentum phase shifts computed from $\pi n$, $\pi \pi$, and $\mathrm{en}$ data via analyticity and unitarity. Each of these three additions has a significant effect on the low angular momentum phase shifts. The resulting $D$-wave phase parameters are in much better agreement with the values produced by potential models than were those produced by the earlier Livermore continuous-energy analysis.

NUCLEAR REACTIONS Phase parameter analysis, 20-30-MeV $pp+np$ data, theoretical input; low-$L$ phases, other analyses, model values.