Bifurcations in Boltzmann–Langevin one body dynamics for fermionic systems

Abstract

We investigate the occurrence of bifurcations in the dynamical trajectories depicting central nuclear collisions at Fermi energies. The quantitative description of the reaction dynamics is obtained within a new transport model, based on the solution of the Boltzmann-Langevin equation in three dimensions, with a broad applicability for dissipative fermionic dynamics.Dilute systems formed in central collisions are shown to fluctuate between two energetically favourable mechanisms: reverting to a compact shape or rather disintegrating into several fragments. The latter result can be connected to the recent observation of bimodal distributions for quantities characterising fragmentation processes and may suggest new investigations.

Isospin effects and symmetry energy studies with INDRA

“…[78], tested in nuclear matter. The recommendation from the above references was to pay special attention to the Pauli blocking; this becomes therefore the direction followed for building the Boltzmann-Langevin One Body model, BLOB [79,80]. With the BLOB simulations, the multifragmentation process can be followed down to low energy where the system explores instabilities against density fluctuations when low densities are attained, and a characteristic spinodal behaviour stands out.…”

Event simulations in a transport model for intermediate energy heavy ion collisions: Applications to multiplicity distributions

“…The two papers which give procedural details of moving two clouds of tps from initial positions to final positions with a stricter adherence to fermionic limits are refs. [9,10]. Multiplicity distributions are not given so we can not compare.…”

“…There are some which can be labeled as "quantum molecular dynamics" type [4,5] These are different in spirit to the model used here. Closer in spirit yet quite distinct are some studies based on a Langevin model [6][7][8][9][10] where we have mentioned only a few. We will have occasion to refer very briefly to only a small number of these.…”

Comparison of radial flow effects on partitions of multifragmenting sources formed in symmetric and asymmetric central collisions

“…This invalidates one of the basic hypotheses of most statistical models of multifragmentation, in which partitions and flow are decoupled in the calculation of the statistical weights [22]. On the other hand, such a coupling occurs naturally in dynamical models capable of simulating the entire history of the formation and multifragmentation of hot compressed nuclear blobs [5,23]. Comparisons with such models are underway and will allow to better understand the fundamentally dynamical nature of the multifragmentation process.…”