Momentum spectra of protons in the reaction of $\gamma +\mathrm{Be}\to p$ + anything in the incident energy range from 180 to 420 MeV were measured. The spectrum obtained shows two peaks which are interpreted to be due to the protons in reactions $\gamma +``N\text{'}\text{'}\to p+\pi$ and $\gamma +``d\text{'}\text{'}\to p+n$, where $``N\text{'}\text{'}$ and $``d\text{'}\text{'}$ are the quasifree nucleons and neutron-proton systems, respectively, in the beryllium nucleus.

• Received 5 May 1980

DOI:https://doi.org/10.1103/PhysRevLett.45.706