Excavation has been completed for the gigantic particle detector that will serve the international Deep Underground Neutrino Experiment (DUNE), which is located at a facility hosted in the former Homestake mine in South Dakota, the biggest and deepest gold mine in North America until its closure in 2002.
Engineering, construction and excavation teams have been working 4,850 feet below the surface since 2021 at the Sanford Underground Research Facility. Construction crews dismantled heavy mining equipment and, piece by piece, transported it underground using an existing shaft.
Once below the surface, workers reassembled the equipment and spent almost two years blasting and removing rock. Close to 800,000 tons of rock were excavated and transported from underground into an expansive former mining area above ground.
Now, the three colossal caverns that are at the core of the new research facility span an underground area about the size of eight soccer fields.
“The completion of the three large caverns and all of the interconnecting drifts marks the end of a really big dig,” said Fermilab’s Michael Gemelli, who managed the excavation of the caverns by Thyssen Mining. “The excavation contractor maintained an exemplary safety record working over a million hours without a lost-time accident. That’s a major achievement in this heavy construction industry.”
Supported by the US Department of Energy’s Fermi National Accelerator Laboratory, DUNE scientists will study the behaviour of mysterious particles known as neutrinos to solve some of the biggest questions about our universe. Why is our universe composed of matter? How does an exploding star create a black hole? Are neutrinos connected to dark matter or other undiscovered particles?
The caverns provide space for four large neutrino detectors—each one about the size of a seven-story building. The detectors will be filled with liquid argon and record the rare interaction of neutrinos with the transparent liquid.
Trillions of neutrinos travel through our bodies each second without us knowing it. With DUNE, scientists will look for neutrinos from exploding stars and examine the behaviour of a beam of neutrinos produced at Fermilab, located near Chicago, about 800 miles east of the underground caverns.
Now that the caverns have been dug out, workers will begin to outfit them with the systems needed for the installation of the DUNE detectors and the daily operations of the research facility. Later this year, the project team plans to begin the installation of the insulated steel structure that will hold the first neutrino detector. The goal is to have the first detector operational before the end of 2028.
The DUNE collaboration, which includes more than 1,400 scientists and engineers from over 200 institutions in 36 countries, has successfully tested the technology and assembly process for the first detector.
Mass production of its components has begun. Testing of the technologies underlying both detectors is underway using particle beams at the European laboratory CERN.