Faddeev-type calculation of three-body nuclear reactions including core excitation

Abstract

Background: The core excitation, being an important reaction mechanism, so far is not properly included in most calculations of three-body nuclear reactions.Purpose: We aim to include the excitation of the core nucleus using an exact Faddeev-type framework for nuclear reactions in the three-body (core + neutron + proton) system. Methods:We employ Alt, Grassberger, and Sandhas (AGS) integral equations for the three-particle transition operators and solve them in the momentum-space framework. The Coulomb interaction is included via the method of screening and renormalization.Results: We calculate elastic, inelastic, and transfer reactions involving 10 Be and 24 Mg nuclear cores.Conclusions: Important effects of the core excitation are found, often improving the description of the experimental data. In the neutron transfer reactions the core excitation effect is by far not just a simple reduction of the cross section by the respective spectroscopic factor. This indicates that widely used extraction of the spectroscopic factors from the ratio of the experimental and theoretical transfer cross sections is unreliable approach.

Reactions with a10Be beam to study the one-neutron halo nucleus11Be

“…A subsequent theoretical work [19] suggested that a reduction in cross section due to core excitation, not taken into account in either DWBA or ADWA analyses, would result in lower values of S being extracted from experimental data at higher beam energies. The current data are not discriminating enough to confirm, or refute, the effects of core excitation in the reaction.…”

“…However, they could equally show a downward trend with increasing beam (or equivalent deuteron) energy. Faddeev-type calculations of 10 Be + d that included dynamic core excitation were subsequently performed by Deltuva [19] for the four energies used in the experiment . The core excitation effects he found in that work are shown in the right panel of Figure 2 (the line shown here is the red line in Figure 5 of [19]).…”

“…Faddeev-type calculations of 10 Be + d that included dynamic core excitation were subsequently performed by Deltuva [19] for the four energies used in the experiment . The core excitation effects he found in that work are shown in the right panel of Figure 2 (the line shown here is the red line in Figure 5 of [19]). R x is defined as (dσ/dΩ) x /(dσ/dΩ) S P , where x and S P are the calculated cross sections with core excitation (in this case in both the n- 10 Be and p- 10 Be channels) and in the single-particle model, respectively.…”

Deuteron-induced nucleon transfer reactions within anab initioframework: First application top-shell nuclei

“…Excitations of the target nucleus have been directly or indirectly accounted for in the CDCC [8] approach, adiabatic threebody models [9] and, recently, in the distorted-wave Born approximation model [10]. Important core excitations effects have also been found in Faddeev-type calculations for nuclear reactions [11]. Multiple core excitations are in particular needed when deuteron stripping reactions populating resonance states of the final nucleus are considered, as it is the case for the CDCC extension to transfer reactions in the continuum [12].…”

Continuum discretised BCS approach for weakly bound nuclei

“…These models are accurate in nuclei with a strong clusterization into few stable fragments as it occurs in the light region of the Segrè Chart. When moving to the study of heavier isotopes, these models require some extension or additional ingredients [10][11][12][13][14][15][16].…”