Study of refractive structure in the inelastic scattering at the incident energies of 250 to 1120 MeV

Abstract

The data of inelastic 16 O+ 16 O scattering to the lowest 2 + and 3 − excited states of 16 O have been measured at E lab = 250, 350, 480, 704 and 1120 MeV and analyzed consistently in the distorted wave Born approximation (DWBA), using the semimicroscopic optical potentials and inelastic form factors given by the folding model, to reveal possible refractive structure of the nuclear rainbow that was identified earlier in the elastic 16 O+ 16 O scattering channel at the same energies. Given the known transition strengths of the 2 + 1 and 3 − 1 states of 16 O well determined from the (e, e ′ ) data, the DWBA description of the inelastic data over the whole angular range was possible only if the absorption in the exit channels is significantly increased (especially, for the 16 O+ 16 O * 2 + exit channel). Although the refractive pattern of the inelastic 16 O+ 16 O scattering was found to be less pronounced compared to that observed in the elastic scattering channel, a clear remnant of the main rainbow maximum could still be seen in the inelastic cross section at E lab = 350 − 704 MeV.

Refractive effects and Airy structure in inelasticO16+C12rainbow scattering

“…The nuclear rainbow has also been observed for inelastic scattering [2,[13][14][15][16][17]. The rainbow in inelastic rainbow scattering makes it possible to understand the interaction potential for the inelastic channels up to the internal region.…”

“…A systematic analysis of the experimental angular distributions was performed using the coupled channels method with an extended double folding potential derived from realistic wave functions for 12 C and 16 O calculated with a microscopic α cluster model and a finite-range density-dependent nucleon-nucleon force. The coupled channels analysis of the measured inelastic scattering data shows consistently some Airy-like structure in the inelastic scattering cross sections for the first 2 + state of 12 C, which is somewhat obscured and still not clearly visible in the measured data.…”

“…For heavy ion systems, an inelastic nuclear rainbow has been observed for 16 [6-10, 17, 28]. Very recently, evidence for a secondary bow in elastic scattering caused by coupling to the inelastic channel has been reported [29].…”

“…The diagonal and coupling potentials for the 16 O+ 12 C system are calculated using the EDF model without introducing a normalization factor:…”

“…(r) is the diagonal (i = j) or transition (i = j) nucleon density of 16 O taken from the microscopic α+ 12 C cluster model wave functions calculated with the orthogonality condition model (OCM) in Ref. [30].…”