Refractive elastic scattering of carbon and oxygen nuclei: The mean field analysis and Airy structures

Abstract

The experimental data on the 16 O+ 12 C and 18 O+ 12 C elastic scatterings and their optical model analysis are presented. Detailed and complete elastic angular distributions have been measured at the Strasbourg Vivitron accelerator at several energies covering the energy range between 5 and 10 MeV per nucleon. The elastic scattering angular distributions show the usual diffraction pattern and also, at larger angles, refractive effects in the form of nuclear rainbow and associated Airy structures.The optical model analysis unambiguously shows the evolution of the refractive scattering pattern. The observed structure, namely the Airy minima, can be consistently described by a nucleus-nucleus potential with a deep real part and a weakly absorptive imaginary part. The difference in absorption in the two systems is explained by an increased imaginary (mostly surface) part of the potential in the 18 O+ 12 C system. The relation between the obtained potentials and those reported for the symmetrical 16 O+ 16 O and 12 C+ 12 C systems is drawn.

Refractive effects in the scattering of loosely bound nuclei

“…Assuming pure Fraunhofer scattering at forward angles, we extract a grazing angular momentum l g Ϸ 15 from the angular spacing ⌬ = / ͑l g +1/2͒. The striking fact is that the same pattern emerges for all four projectile-target combinations, including that for the 9 Be target where a much stronger absorption is expected.…”

“…The beams were prepared using the beam analysis system [22], which allows for the control of the energy spread (⌬E / E up to 1 / 2500) and angular spread (0.1°) of the beam. Self-supporting 9 Be (200 g/cm 2 thick), 12 C ͑260 g/cm 2 ͒, and 13 C ͑390 g/cm 2 ͒ targets were placed perpendicular to the beam in the target chamber of the MDM. The magnetic field of the MDM spectrometer was set to transport fully stripped Li ions to the focal plane where they were observed in the modified Oxford detector [23].…”

“…Using a refined analysis, we return to that study here with new data extending the angular ranges for the 7 Li scattering and adding data for 6 Li scattering. Recent work [8,9] has established that elastic scattering of light, tightly bound heavy ion systems such as 16 …”

“…In this paper we present an analysis of elastic scattering of 6,7 Li on 12,13 C and 9 Be targets at 9 and 19 MeV/ nucleon. The lower energy was chosen in view of our systematic studies of nuclear reactions for astrophysics.…”

Peripheral elastic and inelastic scattering ofO17,18on light targets at 12 MeV/nucleon

“…18 O+ 12 C elastic scattering at barrier energies was measured by Robertson et al [4], by Szilner et al [5] and Rudchik et al [6] at some 5-7 MeV/nucleon. Fresnel scattering of 18 O on 28 Si was measured by Mermaz et al [7] at 56 MeV.…”