Nuclear rainbow scattering and nucleus–nucleus potential

Abstract

Abstract. Elastic scattering of α-particle and some tightly-bound light nuclei has shown the pattern of rainbow scattering at medium energies, which is due to the refraction of the incident wave by a strongly attractive nucleus-nucleus potential. This review gives an introduction to the physics of the nuclear rainbow based essentially on the optical model description of the elastic scattering. Since the realistic nucleusnucleus optical potential (OP) is the key to explore this interesting process, an overview of the main methods used to determine the nucleus-nucleus OP is presented. Given the fact that the absorption in a rainbow system is much weaker than that usually observed in elastic heavy-ion scattering, the observed rainbow patterns were shown to be linked directly to the density overlap of the two nuclei penetrating each other in the elastic channel, with a total density reaching up to twice the nuclear matter saturation density ρ 0 . For the calculation of the nucleus-nucleus OP in the doublefolding model, a realistic density dependence has been introduced into the effective M3Y interaction which is based originally on the G-matrix elements of the Reid-and Paris nucleon-nucleon (NN) potentials. Most of the elastic rainbow scattering data were found to be best described by a deep real OP like the folded potential given by this density dependent M3Y interaction. Within the Hartree-Fock formalism, the same NN interaction gives consistently a soft equation of state of cold nuclear matter which has an incompressibility constant K ≈ 230 − 260 MeV. Our folding analysis of numerous rainbow systems has shown that the elastic α-nucleus and nucleus-nucleus refractive rainbow scattering is indeed a very helpful experiment for the determination of the realistic K value. The refractive rainbow-like structures observed in other quasielastic scattering reactions have also been discussed. Some evidences for the refractive effect in the elastic scattering of unstable nuclei are presented and perspectives for the future studies are discussed.

Ground-state properties of neutron-rich Mg isotopes

“…The def-WS model well reproduces measured σ R for [20][21][22][23][24][25][26][27][28][29][30][31][32] Ne, and the results of the def-WS density with AMD deformation are consistent with those of the AMD density for [20][21][22][23][24][25][26][27][28][29][30]32 Ne and with that of the AMD-RGM density for 31 Ne. The def-WS model with AMD deformation is thus a handy way of simulating AMD or AMD-RGM densities.…”

“…Recently, Nakamura et al [16] suggested through measurements of the one-neutron removal cross section of 31 Ne on C and Pb targets at 240 MeV/nucleon that 31 Ne is a halo nucleus that resides in the island of inversion. Takechi et al [17] measured σ I for Ne isotopes incident on 12 C targets at 240 MeV/nucleon and came to the same conclusion as Nakamura et al Very recently, Takechi et al measured σ R for [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Mg isotopes on C targets at 240 MeV/nucleon [18] and suggested that 37 Mg is a halo nucleus.…”

“…A powerful tool of analyzing measured σ R or σ I microscopically is the folding model with the g-matrix effective nucleon-nucleon interaction [19][20][21][22][23][24][25][26][27][28][29]. For nucleon scattering from stable target nuclei, the folding potential with the Melbourne g-matrix interaction reproduces measured elastic and reaction cross sections systematically with no adjustable parameter [26,29].…”

The high density equation of state: constraints from accelerators

“…Recent NSCL-MSU heavy ion data in combination with transport calculations are consistent with a value of E sym ≈ 31 MeV at ρ 0 and rule out extremely "stiff" and "soft" density dependences of the symmetry energy [21]. The same value has been extracted [18] from low energy elastic and (p,n) charge exchange reactions on isobaric analog states p( 6 He, 6 Li * )n measured at the HMI. At sub-normal densities recent data points have been extracted from the isoscaling behavior of fragment formation in low-energy heavy ion reactions with the corresponding experiments carried out at Texas A&M and NSCL-MSU [19].…”

Elastic and inelastic scattering of 240-MeVLi6ions fromCa40<

“…However, in the analysis of refractive α-nucleus scattering [23] and of light heavy-ion scattering [24,25] an imaginary potential with a shape different from the real potential was required to reproduce elastic scattering beyond the rainbow angle. A hybrid model, where the folding model is used to calculate the real potential and a Woods-Saxon (WS) form is used for the imaginary potential has been successfully used to describe α-and heavy-ion scattering data by several authors [12,21,22,[26][27][28][29][30]. A detailed study of the double-folding approach for α-nucleus scattering on targets in different mass regions was made by D. T. Khoa in 2001 [26].…”