Low-energy corrections to the eikonal description of elastic scattering and breakup of one-neutron halo nuclei in nuclear-dominated reactions

TL;DR

This paper investigates two semiclassical and phase-shift corrections to the eikonal approximation to improve its validity at energies as low as 10 MeV/nucleon for nuclear reactions involving halo nuclei, finding limited success in describing breakup channels.

Contribution

It extends and evaluates two specific corrections to the eikonal model to enhance its applicability at lower energies in nuclear-dominated reactions.

Findings

Corrections improve elastic scattering description.

Corrections do not significantly improve breakup predictions.

Further methods are needed to extend eikonal validity at low energies.

Abstract

Background: The eikonal approximation is a high-energy reaction model which is very computationally efficient and provides a simple interpretation of the collision. Unfortunately, it is not valid at energies around 10 MeV/nucleon, the range of energy of HIE-ISOLDE at CERN and the future ReA12 at MSU. Fukui etal. [Phys. Rev. C 90, 034617 (2014)] have shown that a simple semiclassical correction of the projectile-target deflection could improve the description of breakup of halo nuclei on heavy targets down to 20 MeV/nucleon. Purpose: We study two similar corrections, which aim at improving the projectile-target relative motion within the eikonal approximation, with the goal to extend its range of validity down to 10 MeV/nucleon in nuclear-dominated collisions, viz. on light targets. The semiclassical correction substitutes the impact parameter by the distance of closest approach of the corresponding classical trajectory. The exact continued $S$-matrix correction replaces the eikonal phase by the exact phase shift. Both corrections successfully describe the elastic scattering of one-neutron halo nuclei. Method: We extend these corrections and study their efficiency in describing the breakup channel. We evaluate them in the case of $^{11}\mathrm{Be}$ impinging on $^{12}\mathrm{C}$ at 20 and 10 MeV/nucleon. Results: Albeit efficient to reproduce the elastic channel, these corrections do not improve the description of the breakup of halo nuclei within the eikonal approximation down to 20 MeV/nucleon. Conclusions: Our analysis of these corrections shows that improving the projectile-target relative motion is not the ultimate answer to extend the eikonal approximation down to low energies. We suggest another avenue to reach this goal.