Isospin effects on the mass dependence of the balance energy

Abstract

We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N/Z = 1.16 and 1.33 as well as isobaric systems with N/Z = 1.0 and 1.4. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.

Neutron to proton ratio dependence of energy of vanishing flow: role of system size and collision geometry

“…This is opposite to what has been observed for isobaric pairs (in Ref. [17]), where the EVF increases with an increase in neutron content and was attributed to the dominance of Coulomb repulsion for proton-rich colliding pairs. Moreover, the EVF decreases as we move to heavier colliding pairs from Ca+Ca to Xe+Xe.…”

“…The relative importance among these reaction mechanisms was not clear then [16]. Therefore, to get more insight about the role of the isospin degree of freedom and to explain the relative contribution of these reaction mechanisms, Gautam et al have studied the EVF as a function of the combined mass of the system [17] as well as the collision geometry for isobaric pairs [18]. These studies revealed that systems with higher neutron to proton content (N/Z) have larger EVF as compared to systems with lower neutron to proton content, for all isobaric pairs in central as well as peripheral collisions.…”

Role of model ingredients on the directed flow and its disappearance using isospin dependent quantum molecular dynamics model

“…The dependence of transverse flow to various entrance channel parameters like incident energy [4], system size [2], colliding geometry [5,6], mass asymmetry [7] and isospin of the reacting nuclei [5,8] is well established experimentally as well as theoretically. The energy dependence of transverse flow, in particular is of great importance and it leads to a term known as balance energy (E bal ) or energy of vanishing flow (EVF), where attractive and repulsive interaction counterbalance each other [9].…”

“…Due to extensive available data on balance energy, the corresponding theoretical efforts have also been carried out, but most of the theoretical attempts are limited to a much narrower range [12]. Sood et.al for the first time, carried out a complete and systematic study of mass dependence of balance energy for the reactions ranging from 12 C+ 12 C to 238 U+ 238 U using isospin-independent quantum molecular dynamics (QMD) model [2], but isospin degree of freedom also has good influence on the balance energy [5,8]. Recently, Kumar et al [13] studied mass dependence of balance energy using isospindependent quantum molecular dynamics (IQMD) model but their study was restricted to the mass range between 122 ( 64 Zn+ 58 Ni ) to 394 ( 197 Au+ 197 Au) units.…”

“…The Isospin-dependent Quantum Molecular Dynamics Model (IQMD) [14] model has been used extensively for studying the isospin effects on large number of observables [8,13].…”