Background: Aside from being a one-neutron halo nucleus, 15 C is interesting because it is involved in reactions of relevance for several nucleosynthesis scenarios. Purpose: The aim of this work is to analyze various reactions involving 15 C, using a single structure model based on halo effective field theory (halo EFT) following the excellent results obtained in [P. Capel et al., Phys. Rev. C 98, 034610 (2018)]. Method: To develop a halo-EFT model of 15 C at next to leading order (NLO), we first extract the asymptotic normalization coefficient (ANC) of its ground state by analyzing 14 C(d, p) 15 C transfer data at low energy using the method developed in [J. Yang and P. Capel, Phys. Rev. C 98, 054602 (2018)]. Using the halo-EFT description of 15 C constrained with this ANC, we study the 15 C Coulomb breakup at high (605 MeV/nucleon) and intermediate (68 MeV/nucleon) energies using eikonal-based models with a consistent treatment of nuclear and Coulomb interactions at all orders, and which take into account proper relativistic corrections. Finally, we study the 14 C(n, γ) 15 C radiative capture. Results: Our theoretical cross sections are in good agreement with experimental data for all reactions, thereby assessing the robustness of the halo-EFT model of this nucleus. Since a simple NLO description is enough to reproduce all data, the only nuclear-structure observables that matter are the 15 C binding energy and its ANC, showing that all the reactions considered are purely peripheral. In particular, it confirms the value we have obtained for the ANC of the 15 C ground state: C 2 1/2 + = 1.59 ± 0.06 fm −1. Our model of 15 C provides also a new estimate of the radiative-capture cross section at astrophysical energy: σ n,γ (23.3 keV) = 4.66 ± 0.14 μb. Conclusions: Including a halo-EFT description of 15 C within precise models of reactions is confirmed to be an excellent way to relate the reaction cross sections and the structure of the nucleus. Its systematic expansion enables us to establish how the reaction process is affected by that structure and deduce which nuclear-structure observables are actually probed in the collision. From this, we can infer valuable information on both the structure of 15 C and its synthesis through the 14 C(n, γ) 15 C radiative capture at astrophysical energies.

We analyze the breakup of the one-neutron halo nucleus 11 Be measured at 520 MeV/nucleon at GSI on Pb and C targets within an eikonal description of the reaction including a proper treatment of special relativity. The Coulomb term of the projectile-target interaction is corrected at first order, while its nuclear part is described at the optical limit approximation. Good agreement with the data is obtained using a description of 11 Be, which fits the breakup data of RIKEN. This solves the apparent discrepancy between the dB(E1)/dE estimations from GSI and RIKEN for this nucleus.

Background:The problem of the scattering of a one-neutron halo nucleus by another nucleus might involve an extremely complicated solution, particularly when breakup and rearrangement channels are to be considered. Purpose:We construct a simple model to study the evolution of a single-particle wave function during the collision of a one-dimensional potential well by another well. Method: Our one-dimensional model provides the essential three-body nature of this problem, and allows for a much simpler application and assessment of different methods of solution. To simplify further the problem, we assume that the potential well representing the projectile moves according to a predetermined classical trajectory, although the internal motion of the "valence" particle is treated fully quantum mechanically. This corresponds to a semiclassical approach of the scattering problem, applicable in the case of heavy projectile and target. Different approaches are investigated to understand the dynamics involving one-body halo-like systems: the "exact" time-dependent solution of the Schrödinger equation is compared to a numerical continuum-discretized coupled-channels (CC) calculation presenting various model cases including different reaction channels. Results: This framework allows us to discuss the reaction mechanism and the role of the continuum, the inclusion of which in the CC calculation results to be crucial to reproduce the exact solution, even when the initial and final states are well bound. Conclusions:The dynamical situations under study can be linked to analogous problems solved in a threedimensional (3D) CC framework, so the present model provides a simple tool to understand the main challenges experienced in the usual 3D models with the treatment of the continuum.

We construct a one-dimensional toy model to describe the main features of Borromean nuclei at the continuum threshold. The model consists of a core and two valence neutrons, unbound in the mean potential, that are bound by a residual point contact density-dependent interaction. Different discretization procedures are used (Harmonic Oscillator and Transformed Harmonic Oscillator bases, or use of large rigid wall box). Resulting energies and wave functions, as well as inelastic transition intensities, are compared within the different discretization techniques, as well as with the exact results in the case of one particle and with the results of the dineutron cluster model in the two particles case. Despite its simplicity, this model includes the main physical features of the structure of Borromean nuclei in an intuitive and computationally affordable framework, and will be extended to direct reaction calculations.

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