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Numerical simulation of nucleon systems using a billiard model

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în volumul unei conferinţe

Autori: C. C. Bordeianu, C. Besliu, A. Jipa, D. Felea

Editorial: Proceedings of the International Conference in Computational Science and Education (ICCSE 2006), Rochester, USA, 2006.


We consider several non interacting nucleons moving in a 2D Woods-Saxon type potential well and hitting the vibrating surface. The Hamiltonian has a coupling term between the particle motion and the collective coordinate which generates a self consistent dynamics. The numerical simulation is based on the solutions of the Hamilton equations which was solved using an algorithm of Runge-Kutta type (order 4-5) having an optimized step size, taking into account that the absolute error for each variable is less than 10-6. Total energy is conserved with high accuracy, i.e. approx. 10-6 in absolute value. We analyze the chaotic behavior of the nonlinear dynamics system using phase-space maps, autocorrelation functions, power spectra and Lyapunov exponents.

In this frame we analyse the onset of dynamical behavior in different dynamical regimes prior to nuclear fragmentation. A qualitative and quantitative picture of the achievement of soft chaos is shown for a comparative study between different stages of the nuclear interaction. All the chaos analysis we performed seems to confirm an intermittency type route to chaos. This transition consists of regular (approximately periodic) motion interrupted by burst of chaos at irregular intervals.

Cuvinte cheie: Lyapunov exponent, multifragmentation