Anisotropic flow from hard partons in ultra-relativistic nuclear collisions

Anisotropies of hadronic distribution in nuclear collisions are used for determination of properties of the nuclear matter. At the LHC it is important to account for the contribution to the flow due to momentum transferred from hard partons to the quark-gluon plasma.Comment: 4 pages, proceedings of PANIC 2014 conference, Hamburg, Aug.201

Rapidity correlations of protons from a fragmented fireball

We investigate proton rapidity correlations for a fireball that fragments due to non-equilibrium effects at the phase transition from deconfined to hadronic phase. Such effects include spinodal fragmentation in case of first order phase transition at lower collision energies, and cavitation due to sudden rise of the bulk viscosity at the crossover probed at RHIC and the LHC. Our study is performed on samples of Monte Carlo events. Correlation function in relative rapidity appears to be a sensitive probe of fragmentation. We show that resonance decays make the strength of the correlation even stronger.Comment: 7 pages, 6 figure

Observables of non-equilibrium phase transition

A rapidly expanding fireball which undergoes first-order phase transition will supercool and proceed via spinodal decomposition. Hadrons are produced from the individual fragments as well as the left-over matter filling the space between them. Emission from fragments should be visible in rapidity correlations, particularly of protons. In addition to that, even within narrow centrality classes, rapidity distributions will be fluctuating from one event to another in case of fragmentation. This can be identified with the help of Kolmogorov-Smirnov test. Finally, we present a method which allows to sort events with varying rapidity distributions in such a way, that events with similar rapidity histograms are grouped together.Comment: contribution to NICA white paper, 5 pages, revised version with minor corrections, mainly languag

Fluctuating shapes of the fireballs in heavy-ion collisions

We argue that energy and momentum deposition from hard partons into quark-gluon plasma induces an important contribution to the final state hadron anisotropies. We also advocate a novel method of Event Shape Sorting which allow to analyse the azimuthal anisotropies of the fireball dynamics in more detail. A use of the method in femtoscopy is demonstrated.Comment: contribution to Proceedings of the XXIV Baldin seminar on high energy physics problems (Relativistic Nuclear Physics and Quantum Chromodynamics), Sept. 17-22, 2018, Dubna, Russia, 6 page

Benchmarking of stainless steel cube neutron leakage in Research Center Rez

The integral experiments covering the neutron leakage from geometrically simple assemblies with a 252Cf source inside are very valuable tools usable in validation of transport cross section data, since geometric uncertainties play a much smaller role in simple geometric assemblies than in complex assemblies as for example reactor pressure vessel geometry. Since 252Cf(s.f.) is standard neutron source, the uncertainties connected with the source neutron spectrum can be even neglected. The paper refers on validation efforts of neutron leakage from stainless steel block ~50 x 50 x50 cm in Research Center Rez. Both the neutron leakage flux at a distance of 1 m from the center of the cubical assembly using stilbene spectrometry and the activation rates at different positions of the assembly were evaluated. In addition to experiments, main sources of uncertainty were identified and evaluated. The results of the stilbene measurements are consistent with the activation measurements results