Using sum rules we calculate four energy weighted moments for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ electric dipole photoeffect for a Volkov spin-independent potential with Serber exchange. Our results are ${\sigma }_{-1\mathrm{}}=2.83\mathrm{}$ mb, ${\sigma }_0=119\mathrm{}$ MeV mb, ${\sigma }_1=5430\mathrm{}$ Me${\mathrm{V}}^2$ mb, and ${\sigma }_2=2.76\mathrm{}\times {10}^5$ Me${\mathrm{V}}^3$ mb. We use only the first term in the hyperspherical expansions of the potential and wave function. We invert either two, three, or four of these moments to determine the photoeffect cross section. Results with different numbers of moments agree with each other to about 15%. We find reasonable agreement with measurements of the total photoeffect cross section.

NUCLEAR REACTIONS Photodisintegration of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, moments of photoeffect, hyperspherical harmonics.

• Received 30 September 1982

DOI:https://doi.org/10.1103/PhysRevC.28.82