Nuclear Charge Distributions of Isotone Pairs. II.K39andCa40

Cross sections for electron elastic scattering from ${}_{19}{}^{39}{}_{}{}^{}\mathrm{K}$ and ${}_{20}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are given for the momentum-transfer range from 0.6 to 3.4 ${\mathrm{fm}}^{-1\mathrm{}}$. The data were analyzed by means of a phase-shift code using phenomenological Fermi charge distributions modified with small undulations. The difference of the ${}_{}{}^{39}{}_{}{}^{}\mathrm{K}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ distributions has been compared with a $1d_{\frac{3}{2}}$ proton distribution and with other nuclear models.