03.12.2015: Implementarea etapei II a proiectului a luat sfarsit.

"Simulari cu sistemul YaPT si predictii pentru curgerea materiei nucleare
in ciocniri nucleare relativiste la experimentul CBM"

Contract finantare nr. F09/30.06.2014


One of the main objectives of the research of the nuclear collisions at relativistic energies is the study of nuclear matter phase diagram and locating of the critical point of the phase transition. The most important phase is represented by the quark - gluon plasma. Lattice QCD calculations predict that this phase transition is a second order one, with passing of separating region between hadronic and quarks gluons plasma phase. In this case, it is considered that the flow of almost perfect liquid occurs (Nucl.Phys.A757 (2005) 1-282 , 904-905 (2013)), when the temperature exceeds a critical value of 170-190 MeV. These results are specific to high energy collisions. Experiments at FAIR-GSI offers the possibility to perform experiments under common conditions (collision over a wide range of energies using the same detector system), but at lower temperatures and at higher baryon chemical potential. The predictions 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, continuous type, in the small baryon chemical potential region. Exploring a wide range of collision energies allows us to access some areas of interest, in different representations of the phase diagram (e.g., the temperature and the chemical baryon potential diagram). The existence of a critical point could be revealed by the increase of fluctuations (C.Athanasiou et al - Phys.Rev.D 82 (2010) 074 008). Therefore, the overall objective of the project is to associate different types of flow behavior of nuclear matter in the participant region with different phases of nuclear matter formed in collision. Taking into account the expected behavior near the critical point - increasing fluctuations - an objective of interest is the fluctuation investigation by analyzing the ordinary and factorial moments associated with distributions of interest, especially those of multiplicity, transverse momentum and rapidity. Other physical quantities of interest that can provide information are strangeness fluctuations, temperature, net charge and baryon number fluctuations. If fluctuations are related to the vicinity of the critical point, then one can see deviations from Gaussian-shape of the multiplicity distribution. It could be observed by event-by-event analysis and by a non-monotonic behavior of the associated higher order moments. Event-by-event analysis is superior to an inclusive analysis because it is more sensitive to changes in system state, including to the degree of achievement of the thermodynamic equilibrium, which allows the use of Tsallis statistics (J.Stat.Phys.52 (1988) 479) and analysis of the behavior of the non-extensivity parameter as a function of the available energy. The sensitivity of the event-by-event analysis determined one of the most important objectives of the present research project: using global analysis to highlight different types of flow. By constructing different tensors, using the Cartesian components of the momentum of the particles produced in the same event, we can make some connections with different types of flow, from radial to triangular, with specific phases of nuclear matter and correlation with limit states between phases, such as the cumulative production of particles. Also, we can make predictions for the shape and temporal evolution of the participant region. To achieve the all the proposed objectives, it is absolutely necessary a first step, namely improvement of the YaPT simulation system performance and adding of new features: parallel processing implementation for each of the requests made from the web interface and a prioritization system of the simulations, implementation of a new analysis modules in conjunction with the objectives of this project. Another objective is to improve knowledge related to the detector operation for such measurements.

Autoritatea Contractanta: Institutul de Fizica Atomica, Magurele
Contractor: Facultatea de Fizica, Universitatea din Bucuresti
Director de proiect: Prof.univ.dr. Alexandru JIPA
Durata: 24 luni
Echipa de cercetare

Etapa I an 2014
Etapa II an 2015
Etapa III an 2016

The development and using of simulation programs packages included in YaPT system. Applications for CBM experiment.

The simulations with computing codes for simetric and asimetric collisions at energies available at SIS-100, SIS-300, respectively. The analysis of flowing processes.

The searching for optimal locations of some detectors systems for obtaining of reaction plan for nuclear collisions at CBM-FAIR.
A1.1 - UB-FF The using of specific programs package of detectors systems from CBM experiment.
AII.1 - UB-FF Simulations for simetric collisions available at SIS-100.
AII.2 - UMC The analysis of flowing processes using the global analysis, especially of flowing and thrust tensors.
AII.3 - UB-FF Simulations for asimetric collisions aavailable at SIS-100.
AII.4 - UMC The study of forming of nuclear matter jets and connections with cumulative producing of particles.
AIII.1 -UB-FF Connections between the flowing parameters of nuclear matter and reaction plan. The flowing types.
AIII.2 -UMC Studies for identifying of calorimeters locations for fixing of collision centrality. Connections with the information from multiplicity detectors.