Study of Correlations between Nuclear Flow and Stopping in Heavy-Ion Collisions

Abstract

The present work deals with the study of collective flow and nuclear stopping for mass symmetric and asymmetric colliding nuclei in heavy-ion collisions. The simulations are carried out by using Isospin-dependent Quantum Molecular Dynamics (IQMD) model. The role of mass asymmetry on collective flow and nuclear stopping is studied in detail. The nuclear stopping associated with various fragments is also studied. The correlation of nuclear stopping with directed and elliptical flow is also established.

The present thesis is divided into following five chapters.

Chapter 1 presents the general introduction of heavy-ion collisions in mass symmetric and asymmetric reactions. The various observables and their correlation with nuclear equation of state have been discussed. It also presents the status of the available theoretical and experimental attempts made to understand the collective flow, nuclear stopping and correlations between them.

Chapter 2 gives the details of various theoretical models used in literature to study the heavy-ion collisions. This chapter include detailed explanation of the isospin dependent Quantum Molecular Dynamics model used to study the heavy-ion collisions. Primary model produce the phase space of the nucleons. The secondary model namely minimum spanning tree (MST) method used to analyze the phase space of nucleons generated by the primary models is also discussed.

In Chapter 3, the role of isospin degree of freedom in heavy-ion collisions through the transverse momentum (pt), isospin content ratio and system mass dependence of pt-differential transverse flow is discussed. The results are discussed for the symmetric systems. The pt-differential transverse flow is highly sensitive towards the symmetry energy and its density dependence. The pt-differential transverse flow dependence is found to be more sensitive towards the symmetry energy and its density dependence compared to the energy of vanishing flow. The effect of density dependent symmetry energy under different rapidity bins are discussed and compared the theoretical calculations with the experimental data of FOPI collaboration.

Chapter 4, author has studied the effect of mass asymmetry on nuclear stopping ⟨R⟩ by keeping the total mass fixed. A reasonable significance has found in fragments stopping over the nucleons stopping by comparing the theoretical results with experimental data of INDRA collaboration for nearly symmetric reactions. Correlations between directed transverse flow ⟨Pdirx⟩ and nuclear stopping ⟨R⟩ for mass asymmetric reactions have been studied. The study reveals that at high incident energy, correlation between the directed transverse flow and nuclear stopping follows a linear behavior, while at low incident energy, it follows a parabolic behavior. The positive value of elliptical flow signifies the in-plane particles emission, whereas negative value signifies the out-of-plane particles emission. Author has also studied the behavior of nuclear stopping for different fragments in out-of-plane and in-plane emitted particles by studying the nuclear stopping at and around the transition energy.

Finally, the results along with an outlook is summarized in Chapter 5.