Meet the DUNEs

Inside one of the protoDUNE detectors, currently under construction at CERN (Image: Max Brice/CERN)

A new duo is living in CERN’s test beam area. On the outside, they look like a pair of Rubik’s Cubes that rubbed a magic lamp and transformed into castle turrets. But on the inside, they’ve got the glamour of a disco ball.

These 12m x 12m x 12m boxes are two prototypes for the massive detectors of the Deep Underground Neutrino Experiment (DUNE). DUNE, an international experiment hosted by Fermilab in the United States, will live deep underground and trap neutrinos: tiny fundamental particles that rarely interact with matter.

“Learning more about neutrinos could help us better understand how the early Universe evolved and why the world is made of matter and not antimatter,” said Stefania Bordoni, a CERN researcher working on neutrino detector development.

These DUNE prototypes are testing two variations of a detection technique first developed by Nobel laureate Carlo Rubbia. Each cube is a chilled thermos that will hold approximately 800 tonnes of liquid argon. When a neutrino bumps into an atom of argon, it will release a flash of light and a cascade of electrons, which will glide through the electrically charged chamber to detectors lining the walls.

Inside their reinforced walls sits a liquid-tight metallic balloon, which can expand and contract to accommodate the changing volume of the argon as it cools from a gas to a liquid.

Even though theses cubes are huge, they are mere miniature models of the final detectors, which will be 20 times larger and together hold a total of 72 000 tonnes of liquid argon.

In the coming months, these prototypes will be cooled down so that their testing can begin using a dedicated beam line at CERN’s SPS accelerator complex.