The combined nearside-farside and shadow-surface decomposition for nuclear elastic scattering analyses

In nuclear elastic scattering analyses, the nearside-farside decomposition is widely used. This method can decompose the elastic scattering amplitude into nearside and farside components, corresponding to positive and negative deflection angles, respectively. In addition to this approach, other decomposition methods are also available. The shadowsurface decomposition can split the elastic scattering amplitude into shadow and surface components, which represent the scattering on an absorbing nonreflecting target via Coulomb potential and the scattering in the surface region, respectively. In this work, the combined nearside-farside and shadow-surface decomposition was developed to analyze the features of the angular distribution patterns. This combined decomposition provides an approach to express the refraction-modified two-slit diffraction picture of nuclear scattering. The shadow scattering and the surface one were shown to represent the two-slit diffraction and the refractive modification, respectively. The elastic scattering of 16 O+ 12 C at 1503 MeV was taken as the test example, for which two shallow-/deep-W ambiguous optical potentials were utilized. The shadow-surface and nearside-farside decompositions were performed for this colliding system, respectively. For the shadow and surface components, each was further decomposed into the nearside and farside contributions. The diffraction patterns exhibited in the shadow and surface components were then explained as the interference between their nearside and farside contributions. Simultaneously, the nearside and farside components were also separated into shadow and surface contributions, where the surface refractive modification shows opposite behaviors for the two components.