Errors on Charge Densities Determined from Electron Scattering

Erros on the charge distribution as derived from electron scattering are determined and they depend largely on assumptions about the possible large-$q$ behavior of the form factor (i.e., at larger-$q$ values than have been measured). We use rather general expansions for $\rho \mathrm{}\left(r\right)\mathrm{}$, for example the cosine series or a set of spline functions. We find the charge distribution and its error to be not very dependent on the set of functions used for expansion but dependent instead on assumptions about and knowledge of the errors in $f\left(q\right)\mathrm{}$. Charge densities and their errors for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ based on electron scattering are shown.