2022-08-12 14:17


Conference: Bucharest University Faculty of Physics 2016 Meeting

Section: Nuclear and Elementary Particles Physics

Antiparticle to particle ratios, thermodynamic equilibrium and flow in Au-Au collisions at FAIR-GSI energies

Nicolae George TUTURAS (1), Alexandru JIPA (1), Oana RISTEA (1), Calin BESLIU (1), Marius CALIN (1), Catalin RISTEA (2), Adam JINARU (3), Tiberiu ESANU (3), Adrian CHITAN (3), Liviu NITA (1), Tanase ALIONTE (1)

(1) University of Bucharest, Faculty of Physics, Department of Structure of Matter, Earth and Atmosphere Physics, Astrophysics

(2) Institute of Space Sciences Bucharest-Măgurele

(3) National Institute of Physics and Nuclear Engineering Horia Hulubei Bucharest-Măgurele


antiparticle to particle ratios, baryon chemical potential, rapidity ranges, FAIR energies, freeze-out chemical temperature

At the new facility that is building at GSI Darmstadt (Germany) a different nucleus-nucleus collisions at energies between 2 A GeV and 45 A GeV will be performed. A few detection systems are under construction, now. One of the detection systems that will be used is Compressed Baryonic Matter (CBM). An interesting objective of this experiment is the study of the phase transitions in nuclear matter formed in these conditions. The type of the phase transition and the specific features are other interesting aspects. In the present work we try to extract basic information using antiparticle to particle ratios and thermal model predictions, I connection eith flow processes. Search for the critical point (CP) in connection with the influences of the fluctuations and with the rapidity ranges are presented, too. For the investigations of these aspects, simulations with different codes, mainly AMPT and UrQMD have been used. Taking into account the accelerator systems, as well as those of the detector system, there are conditions for investigation of different phases, including that to the quark-gluon plasma. Experiments at FAIR-GSI, including CBM Experiment, offer the possibility to perform interactions under common conditions, but at lower temperatures and at higher baryon densities, in comparison with experiments performed at others major international laboratories. The predictions based on the simulated data indicate, in this case, that a first-order phase transition can be obtained and the critical point is the point which connects the first-order phase transition to the region of the second order phase transition, being on a continuous type, in the small baryon chemical potential region. Exploration on a wide range of collision energies allows us to access some areas of interest, in different representations of the phase diagram. The main predictions are connected with the flow and thermalization and are useful for future studies. A few interesting results are related to the K-/K+ at the SIS-100 energy energies, at different centralities and rapidities. Interesting comparisons with KaOS and HADES experimental results at energies similar with the lowest energies at SIS-100 (up to 4 A GeV). For example, the KaOS experiment shows that at energies between 3 to 4 A GeV, the K-/K+ ratio increases with collision centrality. The abundence of K- was also connect whit the possible decrease of the kaon mass in dense and hot nuclear matter, due to the magnitude of the strangeness exchange whit a K- in the final state.

Thanks to the Institute of Atomic Physics for financial support awarded in the program Romania-FAIR (grant F09/30.VI.2014).