Spectator matter fragmentation in Au+Au reactions: Phase space analysis

Clusterization in phase space has been analyzed for peripheral Au+Au reactions at 1000 AMeV using simulated annealing clusterization algorithm (SACA). We investigate how these fragments are correlated in phase space and compare our model calculations with minimum spanning tree (MST) method. Our theoretical study highlights the importance of binding energy criterion in recognizing the fragment structure. MST method however, fails to break-up the spectator matter effectively and thus under-estimates the multiplicity of intermediate mass fragments (IMFs).Comment: 2 pages, 2 figure

Momentum Dependence of Nuclear Mean Field and multifragmentation in Heavy-Ion Collisions

We report the consequences of implementing momentum dependent interactions (MDI) on multifragmentation in heavy-ion reactions over entire collision geometry. The evolution of a single cold nucleus using static soft equation of state and soft momentum dependent equation of state demonstrates that inclusion of momentum dependence increases the emission of free nucleons. However, no heavier fragments are emitted artificially. The calculations performed within the framework of quantum molecular dynamics approach suggest that MDI strongly influence the system size dependence of fragment production. A comparison with ALADiN experimental data justifies the use of momentum dependent interactions in heavy-ion collisions

Microscopic approach to the spectator matter fragmentation from 400 to 1000 AMeV

A study of multifragmentation of gold nuclei is reported at incident energies of 400, 600 and 1000 MeV/nucleon using microscopic theory. The present calculations are done within the framework of quantum molecular dynamics (QMD) model. The clusterization is performed with advanced sophisticated algorithm namely \emph{simulated annealing clusterization algorithm} (SACA) along with conventional spatial correlation method. A quantitative comparison of mean multiplicity of intermediate mass fragments with experimental findings of ALADiN group gives excellent agreement showing the ability of SACA method to reproduce the fragment yields. It also emphasizes the importance of clustering criterion in describing the fragmentation process within semi-classical model

Study of fragmentation using clusterization algorithm with realistic binding energies

We here study fragmentation using \emph{simulated annealing clusterization algorithm} (SACA) with binding energy at a microscopic level. In an earlier version, a constant binding energy (4 MeV/nucleon) was used. We improve this binding energy criterion by calculating the binding energy of different clusters using modified Bethe-Weizs\"{a}cker mass (BWM) formula. We also compare our calculations with experimental data of ALADiN group. Nearly no effect is visible of this modification

Entropy and light cluster production in heavy-ion collisions at intermediate energies

The entropy production in medium energy heavy-ion collisions is analyzed in terms of ratio of deuteronlike to protonlike clusters ($d_{like}/p_{like}$) using \emph{quantum molecular dynamics} (QMD) model. The yield ratios of deuteronlike-to-protonlike clusters calculated as a function of participant proton multiplicity closely agree with experimental trends. Our model predictions indicate that full thermodynamical equilibrium may not be there even for the central geometry. The apparent entropy extracted from the yield ratios of deuteronlike-to-protonlike clusters, however, reflects the universality characteristics \emph{i.e.} it is governed by the volume of reaction independent of the target-projectile combination. Our calculations for apparent entropy produced in central collisions of Ca+Ca and Nb+Nb at different bombarding energies are in good agreement with $4\pi$ Plastic Ball data.Comment: 13 pages, 6 figures, in pres

Spectator fragmentation in nucleus-nucleus collisions: Phase space approach

Dynamics of spectator matter break-up in non-central collisions of $^{197}$Au+ $^{197}$Au at 1000 AMeV are explored within framework of quantum molecular dynamics (QMD) model. The phase space of nucleons bound in intermediate mass fragments are studied using two clusterization subroutines. Backtracking the origin of fragments to the time of initial contact between colliding nuclei indicates that \textit{simulated annealing clusterization algorithm} (SACA) results into significant yield of projectile-like and target-like fragments. Simplest clusterization approach based on spatial correlation technique, however, predicted much lesser production probability of fragments in spectator zone.Comment: Abstract accepted in Rutherford Centennial Conference on Nuclear Physics 201