Bimodality: a possible experimental signature of the liquid-gas phase transition of nuclear matter

Abstract

We have observed a bimodal behaviour of the distribution of the asymmetry between the charges of the two heaviest products resulting from the decay of the quasi-projectile released in binary Xe+Sn and Au+Au collisions from 60 to 100 MeV/u. Event sorting has been achieved through the transverse energy of light charged particles emitted on the quasi-target side, thus avoiding artificial correlations between the bimodality signal and the sorting variable. Bimodality is observed for intermediate impact parameters for which the quasi-projectile is identified. A simulation shows that the deexcitation step rather than the geometry of the collision appears responsible for the bimodal behaviour. The influence of mid-rapidity emission has been verified. The two bumps of the bimodal distribution correspond to different excitation energies and similar temperatures. It is also shown that it is possible to correlate the bimodality signal with a change in the distribution of the heaviest fragment charge and a peak in potential energy fluctuations. All together, this set of data is coherent with what would be expected in a finite system if the corresponding system in the thermodynamic limit exhibits a first order phase transition.

30 pages, 31 figures

References in corpus (4)

• Model-independent tracking of criticality signals in nuclear multifragmentation data
• Distribution of the largest fragment in the Lattice Gas Model
• Transverse Velocity Scaling in Au+Au Fragmentation
• Towards the critical behavior for the light nuclei by NIMROD detector

Cited by in corpus (18)

• Nuclear multifragmentation and phase transition for hot nuclei
• Liquid-Gas phase transition in nuclei
• Bimodal behavior of the heaviest fragment distribution in projectile fragmentation
• Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
• Bimodality - a Sign of Critical Behavior in Nuclear Reactions
• Fragment properties of fragmenting heavy nuclei produced in central and semi-peripheral collisions
• Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei
• Looking for bimodal distributions in multi-fragmentation reactions
• Bimodality - a general feature of heavy ion reactions
• Signals of bimodality in the fragmentation of Au quasi-projectiles
• Specific heat and bimodality in canonical and grand canonical versions of the thermodynamic model
• Properties of the largest fragment in multifragmentation: a canonical thermodynamic calculation
• Bimodality and Coulomb effects with a canonical thermodynamic model
• Latent heat of nuclear matter
• Reaction and fusion cross sections for the near-symmetric system ${}^{129}Xe{+}^{nat}Sn$ from $8$ to $35$ $AMeV$
• Extended Gibbs ensembles with flow
• Investigation of the nuclear liquid-gas phase transition in the static AMD
• A model for multifragmentation in heavy-ion reactions