Two-Body Photodisintegration ofHe3

Abstract

A discussion and comparison of the two forms of interaction, A\ifmmode\cdot\else\textperiodcentered\fi{}p and E\ifmmode\cdot\else\textperiodcentered\fi{}r, is given for two-body photodisintegration of ${\mathrm{He}}^{3}$. It is shown that in general the E\ifmmode\cdot\else\textperiodcentered\fi{}r results are much better than the A\ifmmode\cdot\else\textperiodcentered\fi{}p results. Calculations are carried out to 140 MeV to compare with recent data. The Gunn-Irving wave function gives a good fit to the total cross section at all energies, but fails to account for the ground-state matter form factor. A simple three-nucleon ground-state wave function is suggested which adequately reproduces the Coulomb energy, rms radius, and matter form factor (for ${q}^{2}\ensuremath{\lesssim}3.5$ ${\mathrm{F}}^{\ensuremath{-}2}$) of ${\mathrm{He}}^{3}$, but predicts a photodisintegration cross section which is 20% small at the peak, assuming no final-state interactions. The spin magnetic-moment interaction, which Verde has shown is forbidden in the dipole approximation for transitions from a spatially symmetric ground state, is computed without this approximation and is shown to contribute only 1-10% of the total cross section, the larger amount only at high energies.