Microscopic calculations of elastic scattering between light nuclei based on a realistic nuclear interaction

Abstract

Abstract. The elastic phase shifts for the α + α and α + 3 He collisions are calculated in a cluster approach by the Generator Coordinate Method coupled with the Microscopic R-matrix Method. Two interactions are derived from the realistic Argonne potentials AV8' and AV18 with the Unitary Correlation Operator Method. With a specific adjustment of correlations on the α + α collision, the phase shifts for the α + α and α + 3 He collisions agree rather well with experimental data. IntroductionThe aim of this work is to give a microscopic description of elastic collisions based on a realistic interaction while keeping rather simple basis wave functions. We choose to limit our approach to light colliding nuclei and we illustrate it on the α + α and α + 3 He collisions.For a long time the elastic scattering between light nuclei has been studied in the framework of the Generator Coordinate Method (GCM) [1]. In this model, the system made up of the colliding nuclei is described by a superposition of antisymmetrized states of two clusters separated by a variable distance. Each cluster is described by a Slater determinant of harmonic-oscillator states. After elimination of a Gaussian center-of-mass (c.m.) factor, the wave function of the system becomes invariant under translation (if the oscillator parameters of the two clusters are equal) and can be projected on angular momentum and parity [2]. While it has the required symmetries, the wave function does not have the correct asymptotic behavior of a scattering wave function. This problem is solved by the Microscopic R-matrix Method (MRM) [3,4].With the GCM, a large number of elastic collisions are described with a good precision [5,6]. However, such results are obtained by using phenomenological interactions and fitting one or two parameters for each collision or each partial wave.To obtain a more physical description of collisions and to approach an ab initio calculation, the phenomenological interaction has to be replaced by a realistic interaction reproducing nucleonnucleon phase shifts and properties of the deuteron, such as the Argonne [7,8] interactions. However, the study of elastic scattering with a realistic interaction is much more difficult and only a few collisions have been studied up to now [9,10,11].The GCM basis is not suitable for realistic interactions. Thus, we adapt the wave function by applying a unitary operator or equivalently we adapt the interaction by applying the

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