Barrier distributions and signatures of transfer channels in theCa40+Ni58,64fusion reactions at energies around a

Abstract

Background: The nuclear structure of colliding nuclei is known to influence the fusion process. Couplings of the relative motion to nuclear shape deformations and vibrations lead to an enhancement of the sub-barrier fusion cross section in comparison with the predictions of one-dimensional barrier penetration models. This enhancement is explained by coupled-channels calculations including these couplings. The sub-barrier fusion cross section is also affected by nucleon transfer channels between the colliding nuclei. Purpose: The aim of the present experiment is to investigate the influence of the projectile and target nuclear structures on the fusion cross sections in the Ca-40 + Ni-58 and Ca-40 + Ni-64 systems. Methods: The experimental and theoretical fusion excitation functions as well as the barrier distributions were compared for these two systems. Coupled-channels calculations were performed using the CCFULL code. Results: Good agreement was found between the measured and calculated fusion cross sections for the Ca-40 + Ni-58 system. The situation is different for the Ca-40 + Ni-64 system where the coupled-channels calculations with no nucleon transfer clearly underestimate the fusion cross sections below the Coulomb barrier. The fusion excitation function was, however, well reproduced at low and high energies by including the coupling to the neutron pair-transfer channel in the calculations. Conclusions: The nuclear structure of the colliding nuclei influences the fusion cross sections below the Coulomb barrier for both Ca-40 + Ni-58,Ni-64 systems. Moreover, we highlighted the effect of the neutron pair-transfer channel on the fusion cross sections in Ca-40 + Ni-64

Microscopic study ofCa40+Ni58,64fusion reactions

“…Similar results were obtained in Ref. [34], using the Akyüz-Winther nuclear potential and including the same inelastic couplings. However, the diffuseness parameter of the Akyüz-Winther nuclear potential was slightly increased for 40 Ca+ 64 Ni to fit the fusion cross sections around the Coulomb barrier, whereas the only input parameters in the frozen HartreeFock method are those of the Skyrme energy density functional.…”

“…The experimental data are taken from Ref. [34]. For the two studied systems, the CC calculations with no couplings to inelastic and transfer channels underestimate the measured fusion cross sections at sub-barrier energies by about two orders of magnitude.…”

“…Recently, the fusion excitation functions of 40 Ca+ 58 Ni and 40 Ca+ 64 Ni [34] have been measured at energies around and below the Coulomb barrier to study the influence of the projectile and target nuclear structures on the fusion process. CC calculations were performed with the ccfull code [35], using the Akyüz-Winther nuclear potential [36,37] The additional coupling to the two-neutron transfer channel turned out to be essential to describe the large fusion cross sections at sub-barrier energies for this system [34].…”

“…CC calculations were performed with the ccfull code [35], using the Akyüz-Winther nuclear potential [36,37] The additional coupling to the two-neutron transfer channel turned out to be essential to describe the large fusion cross sections at sub-barrier energies for this system [34].…”

Dynamical effects in fusion with exotic nuclei

“…[8][9][10][11] for reviews). Coupling to rotational [2,12,13] and low-lying vibrational [1,2,5,14,15] states, as well as to transfer [4,[16][17][18][19][20] and * kirsten.vo-phuoc@anu.edu.au breakup of colliding partners [21][22][23] have been shown to have a strong impact on fusion.…”