Interplay of Coulomb and symmetry potential in peak fragment production in asymmetric collisions

Role of the nuclear symmetry potential and Coulomb potential is explored on the peak energy of intermediate mass fragments ([Formula: see text]) and on peak multiplicity ([Formula: see text]) and their dependence on mass asymmetry of the reaction is also investigated. The calculations are done using Isospin-dependent Quantum Molecular Dynamics (IQMD) model. We also showed that the momentum-dependent interactions have uniform effects of [Formula: see text] and these effects are independent of mass asymmetry of the reaction. Further, we see that isospin effects that enter through the Coulomb and symmetry potential show much significant role as one increases the mass asymmetry of reaction. Mass asymmetric reactions thus serve a sensitive tool to investigate the nuclear symmetry energy effects.

Participation of nucleons among different harmonics of anisotropic flow

We present the comprehensive interpretation of the momentum distribution of nucleons participating in different kinds of nuclear flow, within the framework of isospin-dependent quantum molecular dynamics (IQMD) model. Our study reveals that the number of nucleons decreases with increasing order of different harmonics ⟨v1⟩, ⟨v2⟩, ⟨v3⟩, and ⟨v4⟩. The magnitude of flow harmonics depends strongly on transverse momentum.

Nuclear stopping power evaluated via free protons emitted in reaction Xe+Sn near fermi energy

The dissipation phenomenon has been studied by simulating the reaction [Formula: see text] with Isospin-dependent Quantum Molecular Dynamics (IQMD) model. The evolution of the isotropic ratio with bombarding energy for the free protons moving forward in the center of mass system in the final state of the reactions, drawn from the experimental measurements by INDRA collaboration, is reproduced with the model in the energy region near and slightly higher than the Fermi energy. Comparison of the data with the simulation obtained using the IQMD model in the cases of different combinations of in-medium effects in two-body collisions, i.e., medium modification of nucleon–nucleon cross-section and Pauli-blocking effect, indicates that the Pauli exclusion principle is indispensable in the microscopic model and the Pauli-blocking in binary interactions dominates the in-medium effects in the heavy-ion reactions in the energy range, even below the Fermi energy. Based on such comparisons, an energy-dependent effective factor responsible for the Pauli-blocking in the binary collisions in heavy-ion collisions in the Fermi energy domain has been extracted.

On the rapidity distribution of nucleons participating in elliptical flow at intermediate energies

The distribution of nucleons participating in elliptical flow is studied for the reactions of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] using isospin-dependent quantum molecular dynamics (IQMD) model for various centrality ranges and over the wide range of intermediate energy. Our findings reveal that the sigma (width) of rapidity distribution obtained varies with mass of colliding system at a given energy. The peak of rapidity distribution decreases with decrease in the mass of colliding nuclei. Transition energy as well as width of rapidity distribution depends on the mass of fragment for a given centrality. Influence of isospin dependent symmetry energy and nucleon–nucleon cross-section can be studied using rapidity distribution. Second transition energy depends on the mass of the fragment. Rotational phenomenon of nucleons can be observed for nucleons participating in elliptical flow.

Probing the Effect of Different Cross Sections in Asymmetric Systems

We present a complete systematic theoretical study of the multifragmentation for asymmetric colliding nuclei in heavy-ion reactions in the energy range between 50 and 1000 MeV/nucleon by using the isospin-dependent quantum molecular dynamics (IQMD) model. We have observed an interesting outcome for asymmetric colliding nuclei. The comparison between the symmetric and asymmetric colliding nuclei for the isospin-independent and isospin-dependent cross sections has been performed. We have found the pronounced effect of different cross sections and mass asymmetry on the nuclear reaction dynamics.

Rapidity distribution as a probe for elliptical flow at intermediate energies

The interplay between spectator and participant matter in heavy-ion collisions is investigated within the isospin-dependent quantum molecular dynamics (IQMD) model in terms of the rapidity distribution of light charged particles. The effect of different types and sizes of rapidity distributions is studied in elliptical flow. The elliptical-flow patterns show the important role of nearby spectator matter on the participant zone. This role is further explained on the basis of the passing time of the spectator and the expansion time of the participant zone. The transition from in-plane to out-of-plane emission is observed only when the mid-rapidity region is included into the rapidity bin. Otherwise no transition occurs. The transition energy is found to be highly sensitive to the size of the rapidity bin, while it is only weakly dependent on the type of the rapidity distribution. These theoretical findings are found to be in agreement with experimental results.

DYNAMICAL AND SEQUENTIAL DECAY EFFECTS ON ISOSCALING AND DENSITY DEPENDENCE OF THE SYMMETRY ENERGY

Isoscaling properties of the primary and final products are studied via isospin dependent quantum molecular dynamics (IQMD) model and the followed sequential decay model GEMINI, respectively. Both primary and final products isoscaling parameter α keeps no significant change for light fragments, but increases with the mass for intermediate and heavy products. The dynamical effect on isoscaling is reflected on the α decreasing a little with the evolution time of the system, and opposite trend for the heavy products. The secondary decay effect on isoscaling is reflected on the increasing of the α value for the final products which experienced secondary decay process. Furthermore the density dependence of the symmetry energy has also been explored for the primary and secondary products, the symmetry energy coefficient can be expressed by the form of C sym (ρ) ~ C0(ρ/ρ0)γ, C0 and γ extracted from the primary products are consistent with the input parameters, but C0 and γ extracted from the final products deviate the input values. In the paper we also suggest that it might be more reasonable to describe the density dependence of the symmetry energy coefficient by the C sym (ρ/ρ0) ≈ C1(ρ/ρ0)γ soft + C2(ρ/ρ0)γstiff with γ soft ≤ 1, γstiff ≥ 1 and C1, C2 constant parameters.