Microscopic positive-energy potential based on the Gogny interaction

Abstract

An analysis of neutron and proton scattering off 40,48 Ca has been carried out. Real and imaginary potentials have been generated using the Nuclear Structure Method for scattering with the Gogny D1S nucleon-nucleon effective interaction. Observables are well described by NSM for neutron and proton elastic scattering off 40 Ca and for neutron scattering off 48 Ca. For proton scattering off 48 Ca, NSM yields a lack of absorption. This discrepancy is attributed to double-charge-exchange contribution and coupling to Gamow-Teller mode which are not included in the present version of NSM. A recipe based on a Perey-Buck fit of NSM imaginary potential and Lane model is proposed to overcome this issue in an approximate way. PACS. PACS-key describing text of that key-PACS-key describing text of that key

Asymmetry dependence of Gogny-based optical potential

“…For evaluation purposes, optical potential is often fitted in order to reproduce a consistent set of reaction observables. Whenever experimental data are not available, one can ideally rely on more microscopic approaches such as Nuclear Field Theory [5,6], Energy Density Functionals (EDF) [7,8,9,10], ab initio approaches [11,12] or mixed approaches such as g-matrix effective interaction folded with EDF density [13,14]. Moreover microscopic approaches can yield a physical guidance for new parametrizations of phenomenological potentials providing form factors for volume and surface parts of the potential, energy dependence, nonlocality shape and parameters, dependence on the isospin asymmetry of the target nucleus.…”

Towards many-body based nuclear reaction modelling

“…Again, when the agreement with experiment is not satisfactory, several actions are possible, as suppressing approximations in the nuclear reaction codes or modifying the nuclear reaction input codes. However, the number of approximations, the model uncertainties and the computing time are still too large to link directly the nucleon-nucleon effective interaction and the reaction codes outputs, so that it remains impossible to adjust the interaction parameters directly on reaction cross sections, even if recent developments might change this restriction in the future [27]. An example of a result obtained at this third step which has implied a modification of the nuclear reaction code producing nuclear level densities is illustrated in Figure 3 and discussed in details in [28].…”

Non local microscopic potentials for calculation of scattering observables of nucleons on deformed nuclei

“…However, it has been shown that this procedure has a significant impact on some scattering observables [6]. In an attempt to treat explicitely non local effects while using microscopic calculations, G. Blanchon et al [1] have derived an optical potential for the scattering of nucleons off 40 Ca, using the Nuclear Structure Method with the Gogny D1S interaction, and have successfully applied it to elastic scattering calculations for energies under 30 MeV.…”

“…Local, phenomenological optical and transition potentials are the most commonly used in coupled channel analyses, with the extrapolation issue associated. Microscopic approches are being developped in order to improve prediction power and solve the aformentionned issue [1]. Potentials obtained microscopically are non local, and recent studies [2][3][4] have emphasized the importance of treating explicitely this nonlocality, and not through a localization procedure.…”