Calculations based on a two-nucleon ($n-p$) absorption mechanism show that the form factor of the residual nucleus plays an important role in determining the shape of the photoproduction cross section in a wide energy range $60 \mathrm{MeV}<~E_{\gamma }<~300 \mathrm{MeV}$.

• Received 30 January 1978

DOI:https://doi.org/10.1103/PhysRevLett.41.80