arXiv subjects

C. O. Dorso

Publications and source records attributed to C. O. Dorso.

42 records · Page 3Linked to original sources

arXiv2002

Classical Drop Phase Diagram and Cluster Distributions

The phase diagram, ($T,ρ$), of a finite, constrained, and classical system is built from the analysis of cluster distributions in phase and configurational space. The obtained phase diagram can be split in three regions. One, low density limit, in which first order phase transition features can be observed. Another one, corresponding to the high density regime, in which fragments in phase space display critical behavior of 3D-Ising universality class type. And an intermediate density region, in which power-laws are displayed but can not be associated to the abovementioned universality class.

nucl-th↗

arXiv2002

Information entropy in fragmenting systems

The possibility of facing critical phenomena in nuclear fragmentation is a topic of great interest. Different observables have been proposed to identify such a behavior, in particular, some related to the use of information entropy as a possible signal of critical behavior. In this work we critically examine some of the most widespread used ones comparing its performance in bond percolation and in the analysis of fragmenting Lennard Jones Drops.

nucl-th↗

arXiv2001

Non equilibrium effects in fragmentation

We study, using molecular dynamics techniques, how boundary conditions affect the process of fragmentation of finite, highly excited, Lennard-Jones systems. We analyze the behavior of the caloric curves (CC), the associated thermal response functions (TRF) and cluster mass distributions for constrained and unconstrained hot drops. It is shown that the resulting CC's for the constrained case differ from the one in the unconstrained case, mainly in the presence of a ``vapor branch''. This branch is absent in the free expanding case even at high energies . This effect is traced to the role played by the collective expansion motion. On the other hand, we found that the recently proposed characteristic features of a first order phase transition taking place in a finite isolated system, i.e. abnormally large kinetic energy fluctuations and a negative branch in the TRF, are present for the constrained (dilute) as well the unconstrained case. The microscopic origin of this behavior is also analyzed.

nucl-th↗

arXiv1999

Lyapunov Exponent, Generalized Entropies and Fractal Dimensions Of Hot Drops

We calculate the maximal Lyapunov exponent, the generalized entropies, the asymptotic distance between nearby trajectories and the fractal dimensions for a finite two dimensional system at different initial excitation energies. We show that these quantities have a maximum at about the same excitation energy. The presence of this maximum indicates the transition from a chaotic regime to a more regular one. In the chaotic regime the system is composed mainly of a liquid drop while the regular one corresponds to almost freely flowing particles and small clusters. At the transitional excitation energy the fractal dimensions are similar to those estimated from the Fisher model for a liquid gas phase transition at the critical point.

chao-dyn↗

arXiv1998

Caloric curve in fragmentation

We study phase transitions of small two dimensional Lennard Jones drops via microcanonical molecular dynamics in a broad energy range. We found that the caloric curve can be extended to high energies to comprehend high evaporation rates and highly non-equilibrium phenomena such as multifragmentation. Multifragmentation appears as a constant temperature region in the caloric curve like the solid-liquid phase transition.

nucl-th↗

arXiv1998

Temperature and energy partition in fragmentation

We study fragmentation of small atomistic clusters via molecular dynamics. We calculate the time scales related to fragment formation and emission. We also show that some degree of thermalization is achieved during the expansion process, which allows the determination of a local temperature. In this way we can calculate the break-up temperature as a function of excitation energy, i.e. the fragmentation caloric curve. Fragmentation appears as a rather constant temperature region of the caloric curve. Furthermore, we show that different definitions of temperature, related to different degrees of freedom, yield very similar values.

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