The Colliderscope: a real-time show

Ninety-six LED lights distributed over the facade of the Niels Bohr Institute (NBI) in Blegdamsvej (Denmark) reproduce the actual signals coming from the Transition Radiation Detector (TRT) in ATLAS. Thanks to the Colliderscope, when a collision occurs below the ground in Geneva, people passing by in Blegdamsvej will be aware of it almost in real-time.


Niels Bohr Institute facade lit up to reflect the latest data from ATLAS-TRT .

The pattern, intensity and duration of the Colliderscope’s flashes of light depend on the physical parameters of particles crossing the ATLAS TRT detector. “At the Colliderscope very little happens randomly”, explains Troels Petersen, a physicist at NBI and one of the people who conceived it. “Particularly interesting events, such as electrons, are shown by a bright light that remains on the facade for several seconds”.

The Niels Bohr Institute has participated in the development of the TRT detector, and this is why the NBI physicist Clive Ellegaard had the idea of involving the artists Morten Skriver and Christian Skeel to develop a work of art in which art and science fuse together. “For an artist, the LHC is one of the greatest and most fantastic symbolic constructions of all time, on a par with the Egyptian pyramids”, said Skriver. “At first sight, science and art seem to be two fundamentally different human endeavours. Science tries, with absolute objective precision, to take the world apart in order to understand how the different parts work together. Art tries to assemble the world in totally subjective and ambiguous expressions. However, both science and art pursue the same goal: they try with intelligence and intuition to come as close as possible to an understanding of the mystery of existence.”

When the LHC starts up again in February, the Colliderscope will be able to show what is happening at the TRT with just a few seconds' delay. The Colliderscope is a satellite exhibition of the Esbjerg Art Museum and is currently scheduled to run until 2011. Support for the Colliderscope comes from the Danish Arts Agency, the Velux Foundation and the Niels Bohr Foundation.

The TRT detector in the ATLAS experiment.

How does the Colliderscope work?
Three parameters measured by the TRT control the way the diode lamps are lit up in the Colliderscope: the momentum and charge of the particle, and the quality of the reconstructed tracks it produces. The momentum of the particles issued from the proton-proton collisions controls the curvature of the light pattern on the building's facade, whereas the charge determines the bending direction. The speed at which lights are lit up follows the momentum log. The quality of the track in the TRT controls the initial intensity of the Colliderscope’s LED lights: higher intensity means best quality of the track reconstruction and slower fading off means best accuracy of the position of the LED with respect to the measured track.

In addition, secondary particles have a specific light time and some LED lights are lit up simultaneously. This is the case for the electrons: since there are no electrons in the colliding protons, the track of an electron in the TRT signifies that "something interesting" happened that warrants extra scrutiny.


More information, pictures are a video are available here.

by Francesco Poppi