The $A_1$ function of the McIntyre model was modified to fit the measured differential cross section of the elastic scattering ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at $E_{\mathrm{lab}}=22.5\mathrm{}$ MeV, which shows extensive structure for large c.m.-system angles. The modified $A_1$ function is a Woods-Saxon type function with a sharp drop for a certain $l$ value. This drop simulates a great number of surface reactions, which diminish the elastic channel in the case of grazing collision.

• Received 2 June 1969

DOI:https://doi.org/10.1103/PhysRevLett.23.176