Elastic Electron Scattering from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

The nuclear-charge form factors for elastic electron scattering on ${\mathrm{Li}}^{6}$ and ${\mathrm{Li}}^{7}$ have been determined from measurements at primary beam energies of 100 to 600 MeV. The maximum square of the momentum transferred to the nuclei was 6.9 ${\mathrm{F}}^{\ensuremath{-}2}$. Absolute values of the cross sections were obtained by comparison with the known absolute proton cross section. For measurements at the primary-beam energy of 100 MeV, however, only the ratio of the ${\mathrm{Li}}^{7}$ cross section to the ${\mathrm{Li}}^{6}$ cross section was measured. The charge form factor for ${\mathrm{Li}}^{7}$ could be interpreted in terms of a simple harmonic-oscillator shell model with a quadrupole contribution described by the underformed $p$-shell model. For this model, the rms charge radius was 2.39\ifmmode\pm\else\textpm\fi{}0.03 F, and the electric-quadrupole moment required for the fit was in excellent agreement with the spectroscopic measurements. The ${\mathrm{Li}}^{6}$ charge form factor could not be interpreted either in terms of the simple harmonic-well shell model, or in terms of the modified harmonic-well model in which the $s$ and $p$ nucleons are permitted to move in potential wells of different strengths. The rms radius obtained for a phenomenological fit to the data was 2.54\ifmmode\pm\else\textpm\fi{}0.05 F. The ratio of the ${\mathrm{Li}}^{6}$ and ${\mathrm{Li}}^{7}$ rms radii, as determined from the 100-MeV measurements, was 1.055\ifmmode\pm\else\textpm\fi{}0.008. This is in agreement with the ratio as determined from the best-fit form factors which were obtained from the complete range in ${q}^{2}$ of the data.

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