We have analyzed recent data for pion elastic scattering on the three-nucleon system to extract the relative neutron-proton radii in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$. Using standard multiple-scattering analysis techniques we determine the difference between the odd radii with an uncertainty of ±0.007 fm and that between the even radii within ±0.010 fm from the existing data. Additional data and improvements in the scattering theory can be expected to lead to a more precise determination. To assess the significance of the extracted radius differences we compare them with radii determined from Faddeev calculations that include charge-symmetry-breaking forces.

• Received 18 December 1989

DOI:https://doi.org/10.1103/PhysRevC.43.1012