Inelastic Scattering of Electrons fromHe4

The inelastic scattering of electrons from ${\mathrm{He}}^4$ which corresponds to a disintegration of the nucleus has been studied for incident electron energies of 400 and 500 Mev at laboratory angles from 45° to 135°. The energy spectra of the scattered electrons were measured, and absolute cross sections were found by comparison with elastic scattering from hydrogen. The curves were corrected for electron radiation. Within the validity of adapting to ${\mathrm{He}}^4$ one of the results of the Goldberg theory of deuteron electrodisintegration, the cross sections at the maxima of the curves give a value of $M{〈\frac{1}{p}〉}_{\alpha }$ of (7.5±1.5), where $M$ is a nucleon mass and ${〈\frac{1}{p}〉}_{\alpha }$ is the expectation value of the reciprocal of the momentum of a nucleon bound in ${\mathrm{He}}^4$. With a single exception, the energy-integrated cross sections $\frac{d{\sigma }_{\alpha }}{d\Omega }$ agree within experimental error with $\frac{d{\sigma }_{\alpha }}{d\Omega }=2(\frac{d{\sigma }_p}{d\Omega }+\frac{d{\sigma }_n}{d\Omega })$, where $\frac{d{\sigma }_p}{d\Omega }$ is the free-proton cross section and $\frac{d{\sigma }_n}{d\Omega }$ is the neutron cross section found from inelastic scattering from deuterium.