Reaction mechanism in odd-even staggering of reaction cross sections

Abstract

It was recently suggested that the odd-even staggering of reaction cross sections is an evidence of the pair- ing anti-halo effect on projectile radii. We define the dimensionless staggering parameters, Γrds and ΓR, for projectile radii and reaction cross sections, respectively, and analyze the relation between Γrds and ΓR for the scattering of 14,15,16C from a 12C target at 83 MeV/A by taking account of projectile-breakup and nuclear- medium effects newly with the microscopic version of the continuum discretized coupled-channels method. The value of ΓR is deviated from that of Γrds by the projectile-breakup effect, the nuclear-medium effect and an effect due to the fact that the scattering are not the black-sphere scattering (BSS) exactly. The projectile-breakup and nuclear medium effects are nearly canceled for ΓR. The remaining non-BSS effect becomes small as an incident energy decreases, indicating that nucleus-nucleus scattering at lower incident energies are a good probe of evaluating Γrds from measured reaction cross sections.