Evidence for L-dependence generated by channel coupling: O scattering from C at 115.9 MeV

Background: In earlier work, inversion of S matrix for 330 MeV O on C resulted in highly undulatory potentials; the S matrix resulted from the inclusion of strong coupling to states of projectile and target nuclei. L-independent S-matrix equivalent potentials for other explicitly L-dependent potentials have been found to be undulatory. Purpose: To investigate the possible implications of the undulatory dynamic polarization potential for an underlying L dependence of the O on C optical potential. Methods: S matrix to potential, SL → V (r), inversion which yields local potentials that reproduce the elastic channel S matrix of coupled channel (CC) calculations, will be applied to the S matrix for 115.9 MeV O on C. Further, SL for explicitly L-dependent potentials are inverted and the resulting L-independent potentials are characterized and compared with the undulatory potentials found for O on C. Results: Some of the undulatory features exhibited by the potentials modified by channel coupling for 115.9 MeV O on C can be simulated by simple parameterized L-dependent potentials. Conclusions: The elastic scattering of O by C is a particularly favorable case for revealing the effective L dependence of the potential modified by channel coupling. Nevertheless, there is no reason to suppose that undularity is not a generic property leading in many cases to the choice: nucleus-nucleus potentials are (i) smooth and L-dependent, (ii) L-independent and undulatory, or (iii) both.