Photoemission of protons from beryllium and carbon in the energy range from 180 to 580 MeV

Momentum spectra of protons in the reactions of $\gamma +\mathrm{Be}\to p+\mathrm{anything}$ and $\gamma +\mathrm{C}\to p+\mathrm{anything}$ were measured in the photon energy range from 180 to 420 MeV for beryllium and from 340 to 580 MeV for carbon by use of a tagged photon beam. The spectrum obtained shows two peaks which are interpreted to be due to the protons in the reactions $\gamma +``N\text{'}\text{'}\to p+\pi$ and $\gamma +``pn\text{'}\text{'}\to p+n$, where "$N$" and "$\mathrm{pn}$" are the quasifree nucleons and proton-neutron systems in the target nuclei.