Heavy-ion collisions

All these animations have been created using output from a single heavy ion collision simulated with the Ultra relativistic Quantum Molecular Dynamics (UrQMD) approach. The OSCAR output for particle data and for hydrodynamic evolution has been converted to xmf/h5 output with the converter program developed for this purpose. The MADAI workbench based on paraview software has been used to generate state-of-the-art 3d visualizations. Read more about the scientific context for these visualizations here.

In this animation a central (b=2 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon, the highest energy that can be reached at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory,  is shown. Each sphere represents a particle scaled by the square root of its mass. The different colors highlight different particle species as indicated in the legend, the lighter colors indicate the corresponding anti-particles.

This is the link to the animation e200_b2_color_id
and the Paraview state-file urqmd_e200_color_id_final

This animation is an artistic view of the two ‘white’ nuclei colliding and producing a ‘colored’ quark gluon plasma in a central (b=2 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon. The spheres represent hadrons produced by the hadron transport approach and have been scaled by the square root of their mass. The colors have been chosen as red, green and blue to reflect the usual analogy of QCD color charges. In practice the particles have been colored according to different ranges of transverse momentum (pt<0.4=green, 0.4< pt<0.8 =blue pt>0.8 = red).

QGP colorsThis is the link to the animation qgpcolors_improved
and the Paraview state-file qgpcolors_improved

This animation highlights the interactions between the particles produced in a central (b=2 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon. The ‘glowing’ effect has been achieved by using the black-body radiation color map and brighten the particles up that have just interacted. An interaction can be an elastic or inelastic collision, resonance formation or decay or string excitation and fragmentation.

This is the link to the animation highlight_interactions
and the Paraview state-file highlight_interactions_improved

This animation uses teardrop glyphs to indicate the direction of the momentum vector of the particles produced in a central (b=2 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon. Only a sub-sample of particles is visualized to allow for clear visibility of the directions the particles are flying in. The glyphs are scaled by the mass of the particles and colored by their transverse energy.

This is the link to the animation teardrop_e200_b2
and the Paraview state-file teardrop_improved

Another way to look at the momentum distribution of the particles in the course of a heavy ion reaction (central (b=2 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon) is to display momentum space directly. The upper left box shows the evolution in coordinate space, the upper right one in transverse momentum space and the lower panel indicates longitudinal momentum space. The particles are colored by their rapidity to distinguish between forward, backward and midrapidity regions. One can see that the major part of the transverse momentum distribution is generated during the original impact of the collision and mainly re-shuffled during the further evolution.

This is the link to the animation momentum_space
and the Paraview state-file urqmd_ecm200b2_differentspaces

This is a screenshot of the initial state of a non-central (b=7fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon. The participants are colored in green and the spectators are colored in red and blue. The almond shaped overlap region in the reaction plane is nicely visible.

The Paraview state file ini_ecc

The inhomogeneous flow development in a heavy ion collision is visualized by plotted the flow vectors in a hydrodynamic simulation colored by the magnitude of the transverse flow vector. The energy density distribution is also shown to indicate where most of the matter is located.

The Paraview state file final_flow

Hybrid approaches that combine ideal relativistic hydrodynamics with hadronic transport are very successful for the modeling of heavy ion collisions. The animations show a  central (b=0 fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon. The particle degrees of freedom in the initial and final stage are represented by spheres scaled by the square root of their mass and colored by rapidity. During the hydrodynamic evolution iso-energy density contours colored by temperature are shown. A wedge in the front has been cut out to make the inner structures visible.


Paraview state file

Another way to display the hydrodynamic evolution is volume rendering. To enhance visibility of structures a transparent wireframe has been added on the outside of the volume.

This is the link to the animation hybrid_e200b2_wedgevolume
and the Paraview state-file hybrid_wedge_volume

One of the goals of heavy ion research is to explore the phase diagram of quantum chromodynamics (QCD). Therefore, the next animation shows the evolution of the fireball during the hydrodynamic evolution displayed in the temperature-baryochemical potential plane. For this animation the customized Gaussian splatter filter has been used and the displayed matter is weighted by the energy density. The line shows the first order phase transition line and the critical endpoint as given by the equation of state used in the calculation.

This is the link to the animation for a central (b=2fm) Au+Au collision at a center of mass energy of 200 GeV per nucleon t_mu_e200