Pre-equilibrium particle emission and critical exponent analysis

Abstract

In two different phase transition models of nuclear fragmentation we show that the emission of pre-equilibrium particles and mixing of events from different classes cannot be ignored in the analysis of nuclear fragmentation data in terms of critical exponents, and we show how the apparent values of the extracted exponents are affected.

Density fluctuations and multifragmentation of nuclear matter

“…Whenever it is necessary, a non vanishing mean value can easily be introduced. The explicit expression of the distribution P [δ̺ k (t)] is 21) with the variance σ 2 k (t) given by…”

“…In order to take into account the quantal nature of the system and the requirement of antisymmetrization, the Quantum Molecular Dynamics model [18] and the more sophisticated Fermionic (Antisymmetrized) Molecular Dynamics model [19,20] have been developed. In addition, percolation [21] and lattice-gas models [22,23] have also been introduced. These models are particularly suitable to deal with the critical phenomena which can be expected to occur in multifragmantation.…”

Statistical description of nuclear break-up

“…The critical behavior observed in experimental data can also be explained within a percolation model [68], or a Fisher's droplet model [67], which correspond to a second order phase transition in the vicinity of the critical point. We must note, however, that the finiteness of the systems under investigation plays a crucial role.…”

Liquid-Gas Phase Transition in Nuclear Multifragmentation

“…Much of the literature in intermediate energy heavyion collisions assumes that when one is seeing a phase transition one is actually seeing critical phenomena [90,91]. To reach the critical point one has to hit the right temperature and the right density.…”