Study of Anisotropic Flow and Rotational Dynamics at Intermediate Energies

Abstract

The present study provides a deep insight on the different aspects of anisotropic flow and rotational dynamics of heavy ion reactions. Initially, the general introduction of the nuclear physics has been discussed. In this thesis, the importance of isospin and rapidity in collective flow, scaling of flow of fragments and rotational features of heavy ion reactions at the intermediate energies region have been described extensively. The theoretical and experimental attempts on the anisotropic flow, scaling of different component of flow and rotational dynamics have also been discussed. A brief survey of various primary models based on isospin degree of freedom explicitly in the literature has also been summarised to study the different aspects of heavy-ion collisions. The model which is used to carry out the present study i.e., Isospin-dependent Quantum Molecular Dynamics model (IQMD) model has been explained in detail. Also, the secondary models such as Minimum Spanning Tree (MST) and its updated versions MSTP have also been discussed. Furthermore, the yield of nucleons participating in elliptic flow has been studied for the reactions of 197 79 Au +197 79 Au, 150 60 N d +150 60 N d, 124 50 Sn +124 50 Sn, 96 44Ru +96 44 Ru, 78 36Kr +78 36 Kr, 48 20Ca +48 20 Ca and 40 20Ca +40 20 Ca for various impact parameter ranges over the intermediate energy region. It has been found that the peak of yield of nucleons/protons as a function of rapidity decreases with decrease in the mass of colliding nuclei. First and second both transition energies depend on the mass of the fragment. Rotational phenomenon of nucleons can be observed for nucleons participating in elliptic flow. The rotational dynamics has been studied for different mass asymmetric systems 122 49 In +126 50 Sn, 114 48 Cs +134 54 In, 100 40 Mo +148 64 Gd, 86 36Kr +162 67 Ho, 71 31Ga +177 71 Lu, 60 28N i +188 76 Os and 50 24Cr +198 78 P t for incident energies ranging between 40 MeV/nucleon and 400 MeV/nucleon for impact parameter range 0.25 < ˆb < 0.45. Our calculations reveal that the time evolutions of rotational quantities for participant and spectator nuclear matter are different in mass asymmetric heavy ion reactions. Theoretical data of BUUmodel’s azimuthal distributions for free protons have been compared successfully with IQMD model calculations. The rotational flow of free protons with increasing incident energies has been observed. Elliptic flow (calculated from the fits of azimuthal distributions of free protons) dependence with energy has also been investigated. In addition to this, scaling of anisotropic flow of fragments has been studied in mass asymmetric nuclear reactions 122 49 In+126 50 Sn, 114 48 Cs+134 54 In, 100 40 Mo+148 64 Gd, 86 36Kr+162 67 Ho, 71 31Ga+177 71 Lu, 60 28N i+188 76 Os, 50 24Cr+198 78 P t and 40 20Ca+208 82 P b for incident energies ranging between 50 MeV/nucleon and 400 MeV/nucleon for the range of impact parameter 0.25 < ˆb < 0.45. Our findings have revealed that strength of flow depends on the fragment mass and mass asymmetry content of the reaction for a rapidity range. Rapidity constraints play a dominant role in the calculation of scaling of flow of fragments. Lastly, the results of the thesis have been summarised along with the prospect for the extension of present work.