Inelastic electron scattering fromHe3andHe4in the threshold region at high momentum transfer

The cross section for inclusive inelastic electron scattering from the helium isotopes has been measured at momentum transfers squared of $0.8\le Q^2\le 5.0$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and $0.8\le Q^2\le 2.4$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The data were taken at 8° and cover the range $0.6<x<\mathrm{}1\mathrm{}$, where $x=\frac{Q^2}{2M_{\mathrm{He}}\nu }$, which includes the elastic peak, nuclear breakup threshold, the high momentum tail of the quasielastic scattering, and pion production. The structure function, $\nu W_2$, derived from the data, is approaching a scaling limit at high $Q^2$. It can be factored into a product of functions of $Q^2$ and of $x$ as predicted by some models.