Cross sections for two-body photodisintegration of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ are calculated in electric-dipole approximation. The calculation is performed within the context of exact three-body theory with the two-nucleon interactions represented by $s$-wave spin-dependent separable potentials fitted to the low-energy nucleon-nucleon scattering data. The two-body photo-disintegration amplitude is expressed in terms of the half-off-shell nucleon plus correlated-pair amplitudes, a method applicable to any weak-process disintegration amplitude. The numerical results indicate: (1) The ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ 90° photodisintegration cross sections are essentially identical in shape, being only slightly displaced at low energy due to the different thresholds, when both initial and final states are treated consistently. (2) The ${}_{}{}^3{}_{}{}^{}\mathrm{He}(\gamma , d)p$ 90° differential cross section has a peak value of approximately 95 μb/sr.

NUCLEAR REACTIONS Photodisintegration of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$; exact three-body calculation; separable potentials; charge-dependent interactions.

• Received 19 August 1974

DOI:https://doi.org/10.1103/PhysRevC.11.29