Photodisintegration of Three-Particle Nuclei

Abstract

We show that the ${\mathrm{He}}^3$ and ${\mathrm{H}}^3$ photodisintegration reactions are to a large extent independent of the detailed properties of the three-nucleon ground state, but depend crucially on the nuclear interaction in the final continuum states. The bound-state properties considered are the analytic form of the principal $S$ state, the asymptotic behavior, the $S^{\prime }$ state, and the two-nucleon short-range repulsion. Since the rms radius of the bound state determines the over-all magnitude of the cross section, predictions of different wave functions with the same radius are compared. The final states are described by the Faddeev equations in the separable approximation. If the final-state interactions are correctly included, then the low-energy cross sections for the ${\mathrm{He}}^3(\gamma , p)d$ reaction are enhanced by 20-25%, and the cross sections for ${\mathrm{He}}^3(\gamma , n)2p$ are reduced by approximately 100%. A simultaneous but rough agreement is possible for the total two- and three-body breakup cross sections and the charge form factors of the three-particle nuclei; but, within the theoretical framework adopted, the two-body differential cross sections at 90° and the charge-form-factor data cannot be reconciled.