Nuclear Dynamics at the Balance Energy

We study the mass dependence of various quantities (like the average and maximum density, collision rate, participant-spectator matter, temperature as well as time zones for higher density) by simulating the reactions at the energy of vanishing flow. This study is carried out within the framework of Quantum Molecular Dynamics model. Our findings clearly indicate an existence of a power law in all the above quantities calculated at the balance energy. The only significant mass dependence was obtained for the temperature reached in the central sphere. All other quantities are rather either insensitive or depend weakly on the system size at balance energy. The time zone for higher density as well as the time of maximal density and collision rate follow a power law inverse to the energy of vanishing flow.Comment: 9 figures, Submitted to Phys. Rev.

Participant-spectator matter at the energy of vanishing flow

We aim to study the participant-spectator matter over a wide range of energies of vanish- ing flow and masses. For this, we have employed different model parameters at central and semi-central colliding geometries. A nearly mass independent nature of the participant matter has been obtained at the energy of vanishing flow. Further, participant matter can also act as an indicator to study the degree of thermalization.Comment: Proceedings of the International Symposium on Nuclear Physics, Mumbai (INDIA), Vol. 54 pg. 452 (2009

On the balance energy and nuclear dynamics in peripheral heavy-ion collisions

We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of $Ne^{20}+Ne^{20}$, $Ca^{40}+Ca^{40}$, $Ni^{58}+Ni^{58}$, $Nb^{93}+Nb^{93}$, $Xe^{131}+Xe^{131}$ and $Au^{197}+Au^{197}$ are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon-nucleon cross-sections between 40 - 55 mb explains the data nicely. Interestingly, balance energy follows a power law $\propto{A^{\tau}}$ for the mass dependence at all colliding geometries. The power factor $\tau$ is close to -1/3 in central collisions whereas it is -2/3 for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.Comment: 13 pages, 9 figures Accepted in IJMPE (in press

Systematic study of the energy of vanishing flow: Role of equations of state and cross sections

We present a systematic study of the energy of vanishing flow by considering symmetric colliding nuclei (between $^{12}$C and $^{238}$U) at normalized impact parameters using variety of equations of state (with and without momentum dependent interactions) as well as different nucleon-nucleon cross sections. A perfect power law mass dependence is obtained in all the cases which passes through calculated points nicely. Further, the choice of impact parameter affects the energy of vanishing flow drastically, demanding a very accurate measurement of the impact parameter. However, the energy of vanishing flow is less sensitive towards the equation of state as well as its momentum dependence.Comment: 9 pages, 2 figure

Sensitivity of the transverse flow towards symmetry energy

We study the sensitivity of transverse flow towards symmetry energy in the Fermi energy region as well as at high energies. We find that transverse flow is sensitive to symmetry energy as well as its density dependence in the Fermi energy region. We also show that the transverse flow can address the symmetry energy at densities about twice the saturation density, however it shows the insensitivity towards the symmetry energy at densities $\rho/\rho_{0}$ $>$ 2. The mechanism for the sensitivity of transverse flow towards symmetry energy as well as its density dependence is also discussed.Comment: Phys. Rev. C (in press)2011 14 pages, 6 figure

Isospin effects on the mass dependence of balance energy

We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N/Z = 1.16 and 1.33 as well as isobaric systems with N/Z = 1.0 and 1.4. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due to the Coulomb repulsion. We also demonstrate clearly the dominance of Coulomb repulsion over symmetry energy.Comment: 5 pages, 3 figures In this version the discussion is in terms of N/Z whereas in the journal the whole discussion is in terms of N/A. The conclusions remain unaffecte

Isospin effects in the disappearance of flow as a function of colliding geometry

We study the effect of isospin degree of freedom on the balance energy (E$_{bal}$) as well as its mass dependence throughout the mass range 48-270 for two sets of isobaric systems with N/Z = 1 and 1.4 at different colliding geometries ranging from central to peripheral ones. Our findings reveal the dominance of Coulomb repulsion in isospin effects on E$_{bal}$ as well as its mass dependence throughout the range of the colliding geometry. Our results also indicate that the effect of symmetry energy and nucleon-nucleon cross section on E$_{bal}$ is uniform throughout the mass range and throughout the colliding geometry. We also present the counter balancing of nucleon-nucleon collisions and mean field by reducing the Coulomb and the counter balancing of Coulomb and mean filed by removing the nucleon-nucleon collisions.Comment: 15 pages, 5 figure