Public outreach in particle physics

Popularization of state-of-the-art research in high-energy physics faces a number of large challenges, which often stems from the abstract quantum field theory description of the Standard Model. Another more basic challenge is the fact that all the elementary particles are just not known by the general public. Graphical visualization as a medium offers a powerful way to explain physics in a more intuitive way, where a show-and-tell type of approach can be taken.

MC-EKRT offers a unique and intuitive view into the highly complicated physics processes happening in heavy ion collisions. This perspective arises from the phenomenological approach to the simulation of the collisions, as the complex collision is described in concrete positions in space and time, and the probabilistic nature of the problem arises from the event-by-event fluctuations of the participating constituents.

MC Event

To celebrate the doctoral defense of my friend Mikko Kuha, I made this piece of art depicting a lead-lead heavy ion collision. Since the lead ions are accelerated to very near the speed of light, in the laboratory frame they become Lorentz contracted along the beam axis, and thus the spherical nuclei—and the nucleons they are composed of—are contracted into thin pancakes. The collision is depicted to have taken place a minute fraction of a second ago, and the nuclei have partially glanced each other. In the affected region, the nucleons have melted away, and a droplet of Quark Gluon Plasma has formed in the wake of the collision. This is illustrated as the spherical droplets of red, blue, green, yellow, purple, and cyan, each representing one of the color and anti-color charges of the strong nuclear interaction. The protruding cones represent particle jets escaping from the collision region at high velocity. The outer surfaces of the lead-pancakes are blue and violet to highlight the blue- and ultraviolet-shift of the wavelengths of light that would reflect off the moving nuclei, and on the other hand, the rearward sides are almost black with a hint of red due to relativistic aberration, and redshift of wavelengths.

The collision is positioned within a miniature LHC accelerator ring, within which a series of UV LEDs are mounted to illuminate the collision sculpture painted with UV reactive paints. On the perimeter of the LHC model are simplified depictions of the CMS, LHCb, ATLAS, and ALICE experiments, going clockwise from the top.

Making of

This collision model was the first 3D model I have ever made, so as only natural, I made it by randomly sampling the physically accurate distribution describing the lead ions in Mathematica. This produces a rest-frame spherical lead nucleus, so the Lorentz contraction must then be applied along the beam axis. This still leaves the off chance that some nucleons are not connected with the majority, so they must then be adjusted by hand, so a connected manufacturable model is achieved.

On the other hand, the spherical droplet depiction of the Quark Gluon Plasma is purely artistic guestimation what it could be like, and was produced by sampling a spatially uniform distribution of spheres of varying sizes withing the intersection of the lead-nucleus beam path cylinders, taking enough sphere samples to produce enough connections between the spheres for 3D print manufacturing.