On the mechanism of¹⁶O+²⁸Si elastic scattering

Abstract

The smooth cut offS-matrixS(l) is parametrized such that it possesses in the complexl-plane a simple pole (L ₀) with a real part equal to the cut off angular momentum (L) and an imaginary part equal to π/2 times the diffuseness parameter Δ. This representation was found to be successful in the description of¹⁶O+²⁸Si elastic scattering data over the energy range 33 MeV≤E _lab≤215.2 MeV. The trajectory of the pole (L ₀) indicates that this¹⁶O+²⁸Si scattering is well defined as a rainbow scattering, and leads to an almost linear variation of the surface thickness parameterd, with the wave numberk

$$d = 0.1(k - 1.4)(3.2 fm^{ - 1} \leqslant k \leqslant 8.2 fm^{ - 1} ).$$

Comparison between character of |S(l)| and those generated from both simple andl-dependent optical model analysis atE _lah=55 MeV (20°<θ<180°) accounted for the present successful fits and indicated dominance of reflection (l≥L≃27) from outer potential barrier.