Four-body DWBA calculations of the Coulomb breakup of 6He

Abstract

We investigate the Coulomb breakup of the two-neutron halo nucleus 6 He by extending the framework of the finite range post form distorted wave Born approximation theory introduced earlier for the description of the breakup of one-neutron halo nuclei. The model can use the realistic three-body wave function for the 6 He ground state. Calculations have been performed for energy, total and parallel momentum distributions of 4 He fragment. The two-body 4 He-neutron and neutron-neutron correlations have also been calculated. Our results are compared with those of an adiabatic model of the Coulomb breakup reactions. The two theories lead to almost identical results. Comparisons are also made with the available experimental data. It is found that the pure Coulomb breakup can describe the bulk of the data taken at below grazing angles. However, a rigorous description of all the available data requires the consideration of the nuclear breakup effects. PACS numbers: 24.50.+g, 25.60.Gc Key words: Coulomb breakup of 6 He, two-neutron halo nucleus, post form DWBA with finite range effects.

α-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier

“…Concerning the structure model, the main approximation involved in our calculation is the assumption of the validity of the di-neutron model. Four-body DWBA calculations have been performed by Chatterjee et al [46] for the scattering of 6 He on Pb and Au at high energies, using a realistic three-body description of the 6 He nucleus. By comparing with a conventional three-body DWBA calculation based upon a di-neutron model of 6 He, they find that the latter calculation gives too large breakup cross section.…”

Four-body continuum-discretized coupled-channels calculations

“…The theoretical understanding of reactions involving a three-body projectile, such as 6 He, is a complicated task because it requires the solution of a four-body scattering problem. At high energies, a variety of approximations have been used such as semiclassical approximations [34][35][36], frozen halo or adiabatic approximations [37,38], multiple scattering expansions [39][40][41], fourbody DWBA [42,43], among others. However, at energies of a few MeV per nucleon, some of these approximations are not justified.…”

Onset of nuclear structure effects in near-barrier elastic scattering of weakly bound nuclei:He6andLiKucuk1, Boztosun2, Keeley3 2009Phys. Rev. C345560View full textAdd to dashboardCite

“…[7]: He has a three-body α + n + n structure, assuming an α + 2 n cluster structure can give physically meaningful results as the three-body wave function of the 6 He ground state has a large di-neutron ( 2 n) component, which dominates the tail of the wave function [2,8]. Thus, while the breakup of 6 He is best described by four-body models [9,10,11,12,13], their numerically demanding nature, combined with the lack of a generally available code able to implement such calculations make the use of standard three-body CDCC calculations attractive in a study of this kind. Therefore, CDCC calculations were performed using the modified two-body di-neutron model of 6 He proposed by Moro et al [3], where the binding energy of the di-neutron in the ground state is increased to 1.6 MeV to give a wave function that well matches that of more physically sophisticated three-body models.…”

“…While detailed comparison with models of the nuclei in question remains difficult due to the many-body nature of the problem (although progress is being made in this direction, see e.g. [9,10,11,12,13,22,23]) it should be possible to make qualitative conclusions concerning the relative strengths of these couplings by a comparison of the relevant near-barrier elastic scattering measurements. Extrapolation of the calculations presented here leads to the conclusion that future experiments to measure the elastic scattering of such nuclei should concentrate on heavy (Z T ≈ 80) targetspreferably 208 Pb or similar -at energies a few MeV above the Coulomb barrier for the systems concerned in order to maximize the structure dependence of the coupling effects.…”