High-Energy Photodisintegration ofHe4

The two-body photodisintegration of ${\mathrm{He}}^4$ into two deuterons has been observed for average photon energies of 221 MeV and 265 MeV. The forward deuteron was detected at a laboratory angle of 45°. Absolute differential cross sections for the process were determined and total cross sections, assuming a ${sin}^2\theta$ ${cos}^2\theta$ angular distribution, were calculated and compared with upper limits on the cross section for the inverse process, $d+d\to {\mathrm{He}}^4+\gamma$. The results were also compared with theoretical estimates for the cross sections using two different wave functions to describe the ${\mathrm{He}}^4$ ground state. Data were also obtained for photoproton emission from ${\mathrm{He}}^4$ and are compared with previous measurements. These latter results are also discussed in the light of the quasideuteron model of Levinger.