Several new examples of electric dipole transitions to final isospin $\frac{3}{2}$ are calculated using the Fabre-Levinger formalism: (i) the Volkov potential (Serber exchange) gives an integrated cross section 4% higher than the O'Connell-Prats sum rule; (ii) the $V^x$ potential (zero force in odd-parity two-body states) gives a ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ photoeffect cross section close to that found by Fabre and Levinger for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$; (iii) transitions to an uncoupled grand orbital three are several percent of those to grand orbital one. Addition of the cross sections for uncoupled states gives poor agreement with the coupled calculation of Fang et al.; (iv) a $V^x$ potential (Wigner-Bartlett exchange) gives an integrated cross section 5% higher than the Thomas-Reiche-Kuhn value. We also calculate for final isospin ½, neglecting coupling to two-body breakup. The $V^x$ potential (zero force in odd-parity two-body states) gives an integrated cross section 23% higher than the O'Connell-Prats value. A Wigner-Bartlett mixture gives a 23% disagreement with the Thomas-Reiche-Kuhn sum rule. The calculated cross section (summed for both isospin states) has a higher and narrower peak than that measured by Gorbonov (summed for two-body and three-body breakup).

NUCLEAR REACTIONS photodisintegration of trinucleon; hyperspherical harmonics.

• Received 3 February 1978

DOI:https://doi.org/10.1103/PhysRevC.18.56