Dependence of fusion on isospin dynamics

Abstract

We introduce a new microscopic approach to calculate the dependence of fusion barriers and cross-sections on isospin dynamics. The method is based on the time-dependent Hartree-Fock theory and the isoscalar and isovector properties of the energy density functional (EDF). The contribution to the fusion barriers originating from the isoscalar and isovector parts of the EDF is calculated. It is shown that for non-symmetric systems the isovector dynamics influence the sub-barrier fusion cross-sections. For most systems this results in an enhancement of the sub-barrier cross-sections, while for others we observe differing degrees of hindrance. We use this approach to provide an explanation of recently measured fusion cross sections which show a surprising enhancement at low $E_\mathrm{c.m.}$ energies for the system $^{40}$Ca+$^{132}$Sn as compared to the more neutron-rich system $^{48}$Ca+$^{132}$Sn, and discuss the dependence of sub-barrier fusion cross-sections on transfer.Comment: 5 pages, 4 figure

Fusion with exotic nuclei using a microscopic approach

“…Very little average proton transfer occurs after 48 Ca+ 132 Sn in agreement with Ref. [34], perhaps because the N/Z ratio of 132 Sn is much higher and is a closer match to the heavier calcium nuclei. It was found that subbarier fusion is enhanced for 40 Ca+ 132 Sn more than what can be accounted for by vibrational states [71].…”

“…In Ref. [34], the isovector contribution to the DC-TDHF fusion potentials for 40,48,54 Ca+ 132 is also related to neutron transfer, compatible with the directions in Fig. 5 and the resulting TDHF fusion barriers in Fig.…”

“…Modern codes solve the TDHF equation in three dimensions and include spin-orbit interaction [18][19][20][21]. Recent applications include vibration [22][23][24][25][26], fusion [27][28][29][30][31][32][33][34], transfer [35][36][37][38][39], quasifission [40][41][42][43][44][45][46] and fission [47][48][49][50][51][52] studies. e-mail: kirsten.vo-phuoc@anu.edu.au…”

Transport properties of isospin asymmetric nuclear matter using the time-dependent Hartree-Fock method

“…Recent TDHF studies have been performed to investigate the charge equilibration in deep-inelastic collisions [46,48] and its impact on the interplay between fusion and transfer reactions [49][50][51][52][53][54]. Recent investigations have also shown that the one-body dissipation mechanisms included in TDHF were the most relevant to describe fully damped reactions such as quasi-fission [55][56][57][58][59][60].…”

How the Pauli exclusion principle affects fusion of atomic nuclei

“…Note also that, once dynamics is included, fusion in these systems may behave differently and static effects on the bare potential could be washed out by the dynamics [33]. In particular, fusion in the 40 Ca+ 48 Ca system is expected to be strongly affected by transfer channels [40,46], a feature which has only recently been studied in microscopic approach [47].…”