Photodisintegration ofHe4in theΔregion

Photoemission of protons from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is measured at ${\theta }_{\mathrm{p}=30\mathrm{}}$°, 60°, 90°, and 105° in the photon energy range between 187 and 427 MeV. From the analysis of the momentum spectrum of protons, the differential cross sections for the photodisintegration of quasifree two-nucleon systems in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ nucleus are deduced as a function of the proton angle and the incident photon energy. The obtained cross sections for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are larger than those for the deuteron photodisintegration by a factor of about 4.5 in the energy region of the present experiment.