Probing halo nucleus structure through intermediate energy elastic scattering

Abstract

This work addresses the question of precisely what features of few body models of halo nuclei are probed by elastic scattering on protons at high centre-of-mass energies. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering crosssections can not, in general, be deduced from knowledge of the total matter density alone.We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead.

Few-body multiple scattering calculations forHe6on protons

“…[5]. In the Glauber calculations, each pairwise NN-scattering operator (S matrix), such as the pnS matrices in Eq.…”

“…In the approach followed by Crespo and Johnson [5] the initial relative momenta between the clusters are neglected in the transition matrix elements. One then obtains an FIA expression of a product of a transition operator and a target form factor…”

“…[8]), although making fewer simplifying assumptions than the Glauber model, are used here only to calculate the single-scattering terms of the full amplitude, whereas the Glauber approach includes higher-order terms. However, higher-order terms have been used elsewhere [5]. We first compare all three approaches at the single-scattering level and then include the higher order terms within the Glauber framework and compare with the experimental data.…”

“…In this approach the (N + 1)-body Schrödinger equation is approximated as a set of effective two-body coupled-channel equations, which take into account bound as well as continuum states (something found to be of great importance when dealing with the scattering of weakly bound systems). However, this method is nontrivial to implement numerically and for the high scattering energies available at today's fragmentation facilities it becomes more practical to use a multiple-scattering expansion of the total transition amplitude (MST) [2][3][4][5][6][7][8].…”

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.…”