The fission processes of 112Sn+112Sn and 116Sn+116Sn are simulated with the combination of the Langevin equation and the statistical decay model. The masses of two fission fragments are given by assuming the process of symmetric fission or asymmetric fission by Monte Carlo sampling with the Gaussian probability distribution. From the analysis of the isotopic/isotonic ratios of the fission fragments from both reactions, the isoscaling behavior has been observed and investigated in detail. Isoscaling parameters α and β are extracted as a function of the charge number and neutron number, respectively, in different widths of the sampling Gaussian probability distribution. It seems that α is sensitive to the width of fission probability distribution of the mass asymmetrical parameter, but β is not. Both α and β drop with increasing beam energy and reduced friction parameter.

Momentum correlation functions of nucleon-nucleon pairs are presented for reactions with C isotopes bombarding a 12C target within the framework of the isospin-dependent quantum molecular dynamics model. The binding-energy dependence of the momentum correlation functions is also explored, and other factors that have an influence on momentum correlation functions are investigated. These factors include momentum-dependent nuclear equations of state, in-medium nucleon-nucleon cross sections, impact parameters, total pair momenta, and beam energy. In particular, the rise and the fall of the strength of momentum correlation functions at lower relative momentum are shown with an increase in beam energy.

New calculations for the total reaction cross sections (σR) have been carried out within the framework of reaction dynamics in the intermediate energy nucleus-nucleus collision. The σR of both the stable and exotic nuclei were reproduced rather well. In addition, some dynamical effects on σR can be easily analyzed. The calculations reflected that σR was sensitive to the nuclear equation of state below 100 MeV/u and to the in-medium nucleon-nucleon cross section at the full energy range addressed.

The 4π array INDRA was used to detect nearly all charged products emitted in Ar + Ni collisions between 52 and 95 MeV/u. The charge, mass and excitation energy E* of the quasi-projectiles have been reconstructed event by event. Excitation energies up to 25 MeV per nucleon are reached. Apparent temperatures obtained from several double isotopic yield ratios Tr0 show different dependences uponE* . T06Li7Li-3Heα yields the highest values, as well as the high energy slopes Ts of the kinetic energy spectra. Two statistical models, sequential evaporation and gas in complete equilibrium, taking into account side feeding and discrete excited states population, show that the data can be explained by a steady increase of the initial temperature with excitation energy without evidence for a liquid-gas phase transition.

The rotational behavior together with in-plane collective flow for the intermediate energy 40Ar+27Al reaction is investigated by analyzing the rapidity-dependent azimuthal distributions with the Boltzmann-Uehling-Uhlenbeck (BUU) model. The azimuthal distributions are fitted by a Legendre polynomial expansion up to the second order. By incorporating the uncertainties in the experimental reaction plane determination into our calculations, quantitative agreement between the calculations and data is obtained. It is found that the rotational behavior at midrapidity depends strongly on the impact parameter. Information about the in-plane collective flow is also extracted from the azimuthal distributions. Both the rotational behavior and the in-plane collective flow depend strongly on the in-medium nucleon-nucleon cross section and nuclear equation of state.

The azimuthal correlation function has been calculated as a function of beam energy and impact parameter for the 40Ar+27Al system from 36 MeV/nucleon to 100 MeV/nucleon via a quantum molecular dynamics (QMD) approach. The anisotropy of the azimuthal correlation at midrapidity interval becomes weaker with increasing beam energy and collision centrality. Around 100 MeV/nucleon the azimuthal correlation tends to be flat which indicates the rotational collective motion disappears. The vanishing of rotation may be due to the short lifetime of the emitter as suggested by the two-particle correlation function at small relative momenta. A method to estimate the fluctuation of the experimental reaction plane with respect to the true reaction plane is presented also via the azimuthal correlation function.

Features of particle emission and critical point behavior are investigated as functions of the isospin of disassembling sources and temperature at a moderate freeze-out density for medium-size Xe isotopes in the framework of the isospin-dependent lattice gas model. Multiplicities of emitted light particles, isotopic, and isobaric ratios of light particles show the strong dependence on the isospin of the dissociation source, but double ratios of light isotope pairs and the critical temperature determined by the extreme values of some critical observables are insensitive to the isospin of the systems. Values of the power law parameter of cluster mass distribution, mean multiplicity of intermediate mass fragments (IMF), information entropy, and Campi’s second moment also show a minor dependence on the isospin of Xe isotopes at the critical point. In addition, the slopes of the average multiplicities of the neutrons (Nn), protons (Np), charged particles (NCP), and IMFs (NIMF), slopes of the largest fragment mass number (Amax), and the excitation energy per nucleon of the disassembling source (E*/A) to temperature are investigated as well as variances of the distributions of Nn, Np, NCP, NIMF, Amax, and E*/A. It is found that they can be taken as additional judgements to the critical phenomena.

The momentum widths of the primary fragments and observed final fragments have been investigated within the framework of an antisymmetrized molecular dynamics transport model code with a sequential decay afterburner (GEMINI). It is found that the secondary evaporation effects cause the values of a reduced momentum width s0, derived from momentum widths of the final fragments, to be significantly less than those appropriate for the primary fragment but close to those observed in many experiments. Therefore, a new interpretation for experimental momentum widths of projectilelike fragments is presented.

Isoscaling behavior is investigated using the isotopic and isobaric yields from an equilibrated thermal source which is prepared by the lattice gas model (LGM) for lighter systems with A=36. The isoscaling parameters a and b are observed to drop with temperature for the LGM with the asymmetric nucleon-nucleon potential. However, the isoscaling parameters do not show a temperature dependence for the LGM with the symmetric nucleon-nucleon potential. The relative neutron or proton density shows a nearly linear relation with the N/Z (neutron to proton ratio) of the system.

An extensive experimental survey of the features of the disassembly of a small quasiprojectile system with A∼36, produced in the reactions of 47 MeV/nucleon 40Ar+27Al, 48Ti, and 58Ni, has been carried out. Nuclei in the excitation energy range of 1–9 MeV/nucleon have been investigated employing a new method to reconstruct the quasiprojectile source. At an excitation energy ∼5.6 MeV/nucleon many observables indicate the presence of maximal fluctuations in the deexcitation processes. These include the normalized second moments of the Campi plot and normalized variances of the distributions of order parameters such as the atomic number of the heaviest fragment Zmax and the total kinetic energy. The evolution of the correlation of the atomic number of the heaviest fragment with that of the second heaviest fragment and a bimodality test are also consistent with a transition in the same excitation energy region. The related phase separation parameter, Sp, shows a significant change of slope at the same excitation energy. In the same region a ∆-scaling analysis for of the heaviest fragments exhibits a transition to ∆=1 scaling, which is predicted to characterize a disordered phase. The fragment topological structure shows that the rank-sorted fragments obey Zipf’s law at the point of largest fluctuations, providing another indication of a liquid gas phase transition. The Fisher droplet model critical exponent τ ∼2.3 obtained from the charge distribution at the same excitation energy is close to the critical exponent of the liquid gas phase transition universality class. The caloric curve for this system shows a monotonic increase of temperature with excitation energy and no apparent plateau. The temperature at the point of maximal fluctuations is 8.3 ± 0.5 MeV. Taking this temperature as the critical temperature and employing the caloric curve information we have extracted the critical exponents β, γ , and σ from the data. Their values are also consistent with the values of the universality class of the liquid gas phase transition. Taken together, this body of evidence strongly suggests a phase change in an equilibrated mesoscopic system at, or extremely close to, the critical point.