Bimodality - a general feature of heavy ion reactions

Abstract

Recently, is has been observed that events with the {\it same} total transverse energy of light charged particles (LCP) in the quasi target region, $E_{\perp 12}^{QT}$, show two quite distinct reaction scenarios in the projectile domain: multifragmentation and residue production. This phenomenon has been dubbed "bimodality". Using Quantum Molecular Dynamics calculations we demonstrate that this observation is very general. It appears in collisions of all symmetric systems larger than Ca and at beam energies between 50 A.MeV and 600 A.MeV and is due to large fluctuations of the impact parameter for a given $E_{\perp 12}^{QT}$. Investigating in detail the $E_{\perp 12}^{QT}$ bin in which both scenarios are present, we find that neither the average fragment momenta nor the average transverse and longitudinal energies of fragments show the behavior expected from a system in statistical equilibrium, in experiment as well as in QMD simulations. On the contrary, the experimental as well as the theoretical results point towards a fast process. This observation questions the conjecture that the observed bimodality is due to the coexistence of 2 phases at a given temperature in finite systems.

accepted PRC

References in corpus (24)

• Modelling the many-body dynamics of heavy ion collisions: Present status and future perspective
• Universality of Spectator Fragmentation at Relativistic Bombarding Energies
• Simulated Annealing Clusterization Algorithm for Studying the Multifragmentation
• Systematics of Stopping and Flow in Au+Au Collisions
• Antisymmetrized molecular dynamics of wave packets with stochastic incorporation of Vlasov equation
• Dynamical effects in multifragmentation at intermediate energies
• The multifragmentation of spectator matter
• Compatibility of localized wave packets and unrestricted single particle dynamics for cluster formation in nuclear collisions
• The microcanonical thermodynamics of finite systems: The microscopic origin of condensation and phase separations; and the conditions for heat flow from lower to higher temperatures
• Bimodal behavior of the heaviest fragment distribution in projectile fragmentation
• Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter
• Fragment Kinetic Energies and Modes of Fragment Formation
• Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
• First order phase transitions: equivalence between bimodalities and the Yang-Lee theorem
• Statistical Multifragmentation of Non-Spherical Expanding Sources in Central Heavy-Ion Collisions
• Fragmentation in Peripheral Heavy-Ion Collisions: from Neck Emission to Spectator Decays
• Bimodality - a Sign of Critical Behavior in Nuclear Reactions
• A "Little Big Bang" Scenario of Multifragmentation
• Experimental Indications for the Response of the Spectators to the Participant Blast
• Equilibrium under flow
• Signals of bimodality in the fragmentation of Au quasi-projectiles
• Statistical Ensembles with Fluctuating Extensive Quantities
• Transverse flow of nuclear matter in collisions of heavy nuclei at intermediate energies
• Multifragmentation - what the data tell us about the different models

Cited by in corpus (13)

• Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) -- A Novel Microscopic N-Body Transport Approach for Heavy-Ion Collisions, Dynamical Cluster Formation and Hypernuclei Production
• Bifurcations in Boltzmann-Langevin One Body dynamics for fermionic systems
• Molecular dynamics description of an expanding $q$/$\bar{q}$ plasma with the Nambu--Jona-Lasinio model and applications to heavy ion collisions at RHIC and LHC energies
• FRIGA, A New Approach To Identify Isotopes and Hyper-nuclei In N-Body Transport Models
• Constrained caloric curves and phase transition for hot nuclei
• First-order derivative of cluster size as a new signature of phase transition in heavy ion collisions at intermediate energies
• Dynamical and statistical bimodality in nuclear fragmentation
• FRIGA, A New Approach To Identify Isotopes and Hypernuclei In N-Body Transport Models
• Distributions of the largest fragment size in multifragmentation: Traces of a phase transition
• Investigation of the nuclear liquid-gas phase transition in the static AMD
• Violent Nuclear Reactions: Large-Amplitude Nuclear Dynamic Phenomena in Fermionic Systems
• Remarks on the non-equilibrium effects and collision dynamics in heavy-ion collisions
• Model independent reconstruction of impact parameter distributions for intermediate energy heavy ion collisions