119234278
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.
119294715
Experimental balance energies and isospin-dependent nucleon-nucleon cross-sections
The effect of different isospin-dependent cross-sections on directed flow is studied for a variety of systems (for which experimental balance energies are available) using an isospin-dependent quantum molecular dynamic (IQMD) model. We show that balance energies are sensitive toward isospin-dependent cross sections for light systems, while nearly no effect exists for heavier nuclei. A reduced cross-section σ = 0.9σ NN with stiff equation of state is able to explain experimental balance energies in most of systems. A power law behavior is also given for the mass dependence of balance energy, which also follows the N/Z dependence.
116887728
Sensitivity of elliptical flow in intermediate energy heavy-ion collisions
The detailed analysis of excitation function of elliptical flow by taking into account the nature of equation of state, nucleon-nucleon cross sections as well as momentum dependent interactions is performed within Quantum Molecular Dynamics (QMD)model. All the observables are found to sensitive towards the elliptical flow. The transition energy is found to be decrease with increase in the size of the fragment in the presence of static equation of state as well as with large cross sections, while, trend gets opposite when momentum dependent interactions are included. At last, the experimental data is verified with static hard equation of state in the presence of large cross sections.
118862615
Systematic Study on System Size Dependence of Global Stopping: Role of Momentum-Dependent Interactions and Symmetry Energy
Using the isospin-dependent quantum molecular dynamical (IQMD) model, we systematically study the role of momentum dependent interactions in global stopping and analyze the effect of symmetry energy in the presence of momentum dependent interactions. For this, we simulate the reactions by varying the total mass of the system from 80 to 394 at different beam energies from 30 to 1000 MeV/nucleon over central and semi-central geometries. The study is carried in the presence of momentum dependent interactions and symmetry energy by taking into account hard equation of state. The nuclear stopping is found to be sensitive towards the momentum dependent interactions and symmetry energy at low incident energies. The momentum dependent interactions are found to weaken the finite size effects in nuclear stopping.
118221659
Role of Momentum Dependent Interactions in Nuclear Stopping
In the present analysis, thousand of events were simulated for the neutron rich reaction of 54Xe131 + 54Xe131, at different impact parameters using hard (HMD) and soft (SMD) momentum dependent equation of state. one can clearly see more stopping in the presence of HMD. Production of LCP's and free particles follows the same trend as stopping parameter R. This simply implies that the fragment production can act as a global indicator for the nuclear stopping.
116542469
Study of gold induced heavy ion collisions using isospin dependent QMD model
We have studied the fragment production mechanism in the set of four reactions 197Au79+12C6, 197Au79+26Al13, 197Au79+63Cu29 and 197Au79+208Pb82. The reactions are simulated at an energy 600 MeV/nucleon and collision geometry is varied from central to peripheral (= b/bmax = 0 to 1). A theoretical investigation has been carried out on the study of mass dependence of intermediate mass fragments (5\leqA\leqAtot/6) and other fragments. It is observed that multiplicity shows a good agreement for low Zbound, but it fails for high Zbound. This failure is due the method of analysis MST which we had used in our analysis, because MST method gives one heavy cluster at the time of high density. The discrepancy between theory and experiments can be removed by using reduced isospin dependent NN cross section and sophisticated clustrization algorithm SACA.
119181819
Correlation between balance energy and transition energy for symmetric colliding nuclei
We study the correlation between balance energy and transition energy of fragments in heavy-ion collisions for different systems at incident energies between 40 and 1200 MeV/nucleon using an isospin-dependent quantum molecular dynamics model. With increasing incident energy, the elliptic flow shows a transition from positive (in-plane) to negative (out-of-plane) flow. This transition energy is found to depend on the size of the fragments, composite mass of the reacting system, and the impact parameter of the reaction. It has been observed that a reduced cross section can explain the experimental data. There is a correlation between transition energy and balance energy as their difference decreases with an increase in the total mass of colliding nuclei.
120172380
Stability of fragments formed in the simulations of central heavy ion collisions
117887312
Influence of momentum dependent interactions on nuclear stopping in symmetric heavy-ion collisions
The role of momentum dependent interactions is studied in nuclear stopping at intermediate energy using an isospin-dependent quantum molecular dynamics model. Present calculations are performed at incident energy between 50 and 1000 MeV/nucleon. Our findings show that nuclear stopping is sensitive towards the impact parameter, incident energies as well as towards the mass of the colliding system. Further, the degree of stopping is suppressed by the inclusion of momentum dependent interactions, whereas the particle production is not affected by the MDI.
118430195
Clustering GCG: a viable option for unified dark matter-dark energy?
We study the clustering Generalized Chaplygin Gas (GCG) as a possible candidate for dark matter-dark energy unification. The vanishing speed of sound 0c{sub s}{sup 2} = ) for the GCG fluid can be obtained by incorporating higher derivative operator in the original K-essence Lagrangian. The evolution of the density fluctuations in the GCG+Baryon fluid is studied in the linear regime. The observational constraints on the model are obtained using latest data from SNIa, H(z), BAO and also for the fσ{sub 8} measurements. The matter power spectra for the allowed parameter values are well behaved without any unphysical features.
16931053
CP-odd weak basis invariants and texture zeros
We construct the CP-odd weak basis invariants from the neutrino mass matrix in a weak basis, in which the charged lepton mass matrix is diagonal, and find the necessary and sufficient conditions for CP conservation. We study the interrelationships between different CP-odd weak basis invariants to examine their implications for the Dirac- and Majorana-type CP violating phases for the phenomenologically allowed Frampton-Glashow-Marfatia texture zero structures of the neutrino mass matrix.