Varinderjit Kaur

Systematic study of multifragmentation in asymmetric colliding nuclei

We present a complete systematically theoretical study of multifragmentation for asymmetric colliding nuclei for heavy-ion reactions in the energy range between 50 MeV/nucleon and 600 MeV/nucleon by using soft and hard equations of state. This study is performed within an isospin-dependent quantum-molecular dynamics model. To see the effect of mass asymmetry, simulations are carried out in the absence of Coulomb interactions. Coulomb interactions enhance the production of fragments by about 20%. We envision an interesting outcome for large asymmetric colliding nuclei. Although nearly symmetric nuclei depict a well-known trend for rising and falling with a peak around E=100 MeV/nucleon, this trend, however, is completely missing for large asymmetric nuclei. Therefore, experiments are needed to verify this prediction.

On the elliptical flow and mass asymmetry of the colliding nuclei

Abstract A study of elliptical flow is carried out for different mass asymmetries of colliding nuclei using the reactions of Cr 50 24 + Ru 102 44 ( η = 0.3 ), S 32 16 + Sn 120 50 ( η = 0.5 ) and O 16 8 + Xe 136 54 ( η = 0.7 ). The present reactions are simulated at incident energies between 50 and 250 MeV/nucleon within the framework of isospin-dependent quantum molecular dynamics model. For the present analysis, total mass of colliding pairs is kept fixed and mass asymmetry is varied between 0.3 and 0.7. The elliptical flow shows a transition from in-plane to out-of-plane in the mid rapidity region with incident energy. The transition energy is found to increase with the mass asymmetry for light charged particles. A good agreement is obtained with experimental measurements.

On nuclear stopping in asymmetric colliding nuclei

Abstract Using the isospin-dependent quantum molecular dynamics (IQMD) model, nuclear stopping is analyzed in asymmetric colliding channels by keeping the total reacting mass fixed. The calculations have been performed by varying the mass asymmetry of the colliding pairs with different neutron–proton ratios at an incident beam energy of 250 MeV/nucleon. We find sizable effects of mass asymmetry on nuclear stopping and on the equilibrium of the nuclear matter. A reasonable agreement is also observed between the experimental data and our present calculations.

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.

Phase space analysis of fragmentation and the role of mass asymmetry

Based on the quantum molecular dynamics picture, we aim to understand heavy-ion collisions in terms of participant spectator matter leading to various fragments of different sizes. The study is performed for symmetric as well as asymmetric reactions at E = 200 MeV nucleon−1 for central collisions. Our results highlight the importance of a phase space analysis of the fragment distribution in symmetric and asymmetric collisions in terms of light mass fragments that are a component of participant matter and intermediate mass fragments, which come from the spectator region.

Mass independence and asymmetry of the reaction: Multi-fragmentation as an example

We present our recent calculations on fragmentation by varying the mass asymmetry of the colliding nuclei using the reactions of 26Fe56 +44 Ru96 (? = 0.2), 24Cr50 + 44 Ru102 (? = 0.3), 20Ca40 +50 Sn112 (? = 0.4), 16S32 +50 Sn120 (? = 0.5), 14Si28 +54 Xe124 (? = 0.6), 8O16 +54 Xe136 (? = 0.7) at a fixed center of mass energy Ec.m. = 250 MeV/nucleon. For the present study, total mass of the system is kept constant (ATOT = 152). The measured distributions are given as a function of the total charge of all projectile fragments, Zbound. The well known trend of rise and fall in the multiplicity of intermediate mass fragments for symmetric colliding nuclei is reproduced nicely. Such trends are, however missing for larger asymmetric reactions.

Asymmetry effects in fragment production

The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping Atotal fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of 197Au+27Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

On the elliptic flow for nearly symmetric collisions and nuclear equation of state

We present the results of elliptic flow for the collision of nearly symmetric nuclei (

Heavy ion collision dynamics of 10,11B+10,11B reactions

_{10}{\rm Ne}^{20}+\,_{13}{\rm Al}^{27}

Dependence of the energy of vanishing flow on different components of the nuclear potential

,