180° Electron Scattering fromHe3andHe4at 56 MeV

Abstract

The nuclear magnetic structure of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has been investigated by 180° scattering of 56.6-MeV electrons. The first observation of the $M1\mathrm{}$ continuum in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ from 6 to 20 MeV is reported. The $M1\mathrm{}$ component of the breakup from ${}_{}{}^3{}_{}{}^{}\mathrm{He}(e, e^{\prime })d, p$ together with ${}_{}{}^3{}_{}{}^{}\mathrm{He}(e, e^{\prime })p, p, n$ has been measured and is discussed in light of possible isovector and isoscalar meson-exchange currents in the trinucleon system. The elastic magnetic form factor of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at $q=0.561\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$ is 0.80, giving a rms magnetic radius $a=1.94\mathrm{}\pm 0.19$ fm.