Be9 scattering with microscopic wave functions and the continuum-discretized coupled-channel method

Abstract

We use microscopic 9 Be wave functions defined in a α + α + n multicluster model to compute 9 Be+target scattering cross sections. The parameter sets describing 9 Be are generated in the spirit of the Stochastic Variational Method (SVM), and the optimal solution is obtained by superposing Slater determinants and by diagonalizing the Hamiltonian. The 9 Be three-body continuum is approximated by square-integral wave functions. The 9 Be microscopic wave functions are then used in a Continuum Discretized Coupled Channel (CDCC) calculation of 9 Be+ 208 Pb and of 9 Be+ 27 Al elastic scattering. Without any parameter fitting, we obtain a fair agreement with experiment. For a heavy target, the influence of 9 Be breakup is important, while it is weaker for light targets. This result confirms previous non-microscopic CDCC calculations. One of the main advantages of the microscopic CDCC is that it is based on nucleon-target interactions only; there is no adjustable parameter. The present work represents a first step towards more ambitious calculations involving heavier Be isotopes.

Microscopic Description of $${^{8}{\hbox {Li}}{+}}$$ 8 Li + Nucleus and of $${^{8}{\hbox {B}}{+}}$$

“…These nuclei are described by 8-body wave functions, defined in the framework of the RGM/GCM. This model provides a fair description of spectroscopic properties, except for the B(E2) in 8 Li, whose experimental value is larger by one order of magnitude. This disagreement confirms previous theoretical works [23,20,24].…”

“…As we will see in the next subsection, typical values are K max ∼ 16 − 20. Compared to 6 He, the numbers of components are nearly twice as large, since the symmetry of the two neutrons in 6 He does not exist in 8 Li and in 8 B.…”

“…We choose S 0 = 37 MeV.fm 5 , which approximately reproduces the energies of the 7 Li(1/2 − ) and 7 Be(1/2 − ) first excited states. For u, we take u = 0.9616 for 8 Li and u = 0.9598 for 8 B, which reproduce the binding energies with respect to the α + t + n and α + 3 He + p three-body threshold (−4.49 MeV and −1.72 MeV, respectively). Notice that, with this choice, the binding energies of 7 Li and 7 Be are slightly underestimated (−1.80 MeV for 7 Li and −0.98 MeV for 7 Be, to be compared to the experimental values −2.47 MeV and −1.59 MeV, respectively).…”

“…The conditions of the GCM description of 8 Li have been given in Sect.2.2. Figure 4 shows the pseudostates included in the calculation (energies are given with respect to the α + t + n threshold).…”

“…These problems have been recently addressed by using a microscopic description of the projectile (MCDCC, see Refs. [6][7][8]). In the MCDCC approach, the projectile wave functions are obtained from a nucleon-nucleon interaction.…”