Quantal description of nucleon exchange in a stochastic mean-field approach

Abstract

Nucleon exchange mechanism is investigated in central collisions of symmetric heavy-ions in the basis of the stochastic mean-field approach. Quantal diffusion coefficients for nucleon exchange are calculated by including non-Markovian effects and shell structure.

Quantal nucleon diffusion: Central collisions of symmetric nuclei

“…From Figs. 1-4, we observe that in the collisions of neutron rich nuclei, 28 O + 28 O and 48 Ca + 48 Ca, the neutron variances are larger than the proton variances, while in the collisions of 40 Ca + 40 Ca and 56 Ni + 56 Ni nuclei the variances are nearly equal. In neutron rich nuclei, due to halo structure, the tail of neutron distribution extends further outward, while the proton distribution, particularly in 28 O nucleus, behaves like an inert core.…”

“…We also notice from Figs. 2-3, the quantal variances in the system 40 Ca + 40 Ca are nearly 40% smaller than the semi-classical variances, while in 48 Ca + 48 Ca system the quantal and the semi-classical variances are nearly the same. We believe that this difference appears partly as a result of the more compact quantal structure of 40 Ca than the neutron rich isotope 48 Ca.…”

“…Employing the quantal diffusion mechanism described in the previous section, we investigate nucleon exchange mechanism in the central collisions of 28 O + 28 O, 40 Ca + 40 Ca, 48 Ca + 48 Ca, and 56 Ni + 56 Ni systems at bombarding energies slightly below the fusion barriers. Calculations were done in a three-dimensional Cartesian geometry with no symmetry assumptions [42] and using the Skyrme SLy4d interaction [43].…”

“…This is a very difficult task to accomplish. In a previous work, we carried out an approximate description of the correlation function by calculating it with a set of particle-hole states and increasing the volume of the particle-hole space step by step [40]. We observed that the convergence of such a calculation was very slow and required ever increasing computational time to proceed.…”

Dynamical effects in fusion with exotic nuclei

“…One problem is the difficulty to incorporate transfer channels in coupled-channel calculations [91][92][93][94]. Alternatively, microscopic approaches can also be used to study transfer reaction mechanisms in heavy-ion collisions [95][96][97]. Here, our study of transfer channels is motivated by the observation of an increase of the fusion barrier in 52,54 Ca+ 116 Sn in TDHF calculations and which cannot be explained by vibrational couplings (see Fig.…”