ANALYSIS OF AN UNUSUAL POTENTIAL AMBIGUITY FOR O-16 PLUS O-16 SCATTERING

Woods-Saxon optical-potential fits to recent measurements of O-16 + O-16 elastic scattering at 350 MeV have been interpreted as providing clear evidence for a nuclear rainbow. Three model-independent potentials have also recently been found to reproduce these data. Two of them were indeed found to be members of a rainbow series, in which a distinctive minimum near 44-degrees is the first or second Airy minimum of a rainbow pattern, but the scattering by the third (shallower) potential was less easy to interpret. We show here that this potential achieves its fit to the data by a different and somewhat unconventional mechanism. This serves as a reminder that ambiguities in interpretation can persist, even with as extensive and accurate a data set as this measurement provides.