Analysis of the transverse momentum collective motion in heavy-ion collisions below 100 MeV/nucleon

Abstract

A theoretical analysis of collective momentum transfer is performed in heavy-ion reactions below 100MeV/nucleon in the Landau-Vlasov approach. The nucleon-nucleon cross section, atomic mass, compressibility, and effective mass dependences are analyzed. The simulation of detector acceptances and of finite number of detected particles are discussed. In connection with recent experiments, theoretical results and experimental data are confronted taking into account the experimental constraints. Finite range forces of the Gogny type connected with different nuclear matter incompressibilities are used and the ensuing sensitivity of the Bow is studied. The question whether the Sow provides information on out-of-equilibrium matter properties is investigated.PACS number(s): 25.70.Gh, 24. 10.i

Screening effects on the elastic nucleon-nucleon cross section in relativistic nuclear matter

“…It is therefore not possible to disentangle completely the effects coming from the equation of state or from a reduced cross section. It has lately been found by several authors, from BUU [4,5,6,7,8] as well as QMD [9] or AMD [10] calculations, that a lower cross section in the medium is favoured by a detailed analysis of the transverse flow. Moreover, the cross section is an essential parameter in the calculation of transport coefficients and the knowledge of its screened behavior allows the determination of these coefficients as functions of the thermodynamical state.…”

Participant-spectator matter at the energy of vanishing flow

“…As reported in Ref., [10,11,13,22,28] the energy of vanishing flow exhibits (A −τ ) power law mass dependence. Naturally, the lighter colliding nuclei have higher balance energy whereas heavier colliding nuclei have smaller balance energy.…”

Initialization effects via the nuclear radius on transverse in-plane flow and its disappearance

“…Puri and co-researchers have used the momentum dependence of the mean field within the Quantum Molecular Dynamics (QMD) approach to justify the power law for the entire mass range lying between 12 C+ 12 C and 197 Au+ 197 Au and stated the need of momentum-dependent interactions when dealing with lighter systems ( 12 C+ 12 C) as these provide necessary transverse momenta to lighter systems during the initial phase of the reaction [3]. Mota et al [11] using a Landau-Vlasov formulation (which guarantees that good ground-state properties of finite nuclei such as binding energies and mean square radii are achieved) calculated the balance energy of 12 C+ 12 C (using free nucleon-nucleon cross-sections and a soft EOS with momentum dependence of the mean field) to be around 120 MeV/nucleon. In the context of another study, Antisymmetrized Molecular Dynamics (AMD) model [12] calculations predicted the value of the balance energy for the reaction of 12 C+ 12 C to be around 100 MeV/nucleon with same set of parameters used in the LandauVlasov Approach.…”

“…The balance energy (representing the vanishing of flow) is of great significance because the experimentally determined balance energy can be easily compared with various theoretical calculations as it is free from any experimental uncertainties. Detailed theoretical studies using various transport models have revealed its sensitivity to the EOS and the in-medium nucleon-nucleon crosssection as well as to various entrance channel parameters [6,[8][9][10][11][12]. At the same time, the collective transverse flow and its disappearance has also been found to depend on the isospin degree of freedom [13,14].…”