374 research outputs found
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
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