DUNE: US lowers first steel beam a mile underground for neutrino experiment

The US government-run Fermi National Accelerator Laboratory, also known as Fermilab, and South Dakota-based Sanford Underground Research Facility (SURF) have successfully completed the first test lift and lowering of a six-ton L-shaped steel beam that would be used in the construction of the Deep Underground Neutrino Experiment (DUNE) in the city of Lead, South Dakota. The outcome is being touted as a significant step that would aid engineers to foresee challenges going forward.

DUNE is a global collaboration, with CERN contributing the steel components as an in-kind donation. The initial overseas shipment of beams earlier this year is just the first of 2,100 structural elements expected to be delivered to SURF early next year.

After a year of planning, the collaboration between Fermilab, SURF, and CERN has made steady progress. Jolie Macier, far detector and cryogenics project manager at Fermilab, emphasized the collaborative nature of the effort and the support from all partners involved.

For the lowering of the L-beam, it was critical to maintain the correct tipping angle, as it cannot exceed five degrees, according to Sanmitra Pingulkar, a mechanical engineer with Fermilab . The beam had to fit within the cage and shaft footprint, and crews needed to ensure that the total load did not exceed 13,500 pounds, with the L-beam itself accounting for 90% of that weight.

The goal of the team was to ensure a smooth and safe process when lowering large steel components into the shaft. Jeff Barthel, rigging supervisor at SURF, highlighted the importance of the tests, noting that they help identify improvements to make the task safer and more efficient as they prepare to lower the many cryostat components needed for the Far Site Detectors. “We don’t want any surprises when we’re lifting heavy steel items into the shaft,” Barthel noted .

Clues to the origin of matter

The first two beams, delivered in January, are part of the framework for DUNE’s cryogenic vessels at the Long-Baseline Neutrino Facility. Once combined with the existing 2,500 tons of steel, they will create a 216-foot-long, 62-foot-wide, and 60-foot-high structure.

The structure will house a particle detector filled with 17,000 tons of liquid argon cooled at minus 302 degrees fahrenheit. Scientists will then use these detectors to study neutrinos , elusive particles that are difficult to observe. This is expected to shed more light on how neutrinos behave and transform into multiple states, and even provide clues regarding the how matter originated in the universe.

Beam of neutrinos will travel 800 miles

Crews at SURF constructed a full-scale wooden replica of an L-beam last spring. Although the mockup was much lighter than the actual steel component, its shape and center of gravity provided valuable insights into how to effectively handle the steel structures.

So far, SURF has conducted 350 lifts for the LBNF/DUNE project. This work involves analyzing load dynamics, understanding the limitations of rigging equipment, and minimizing risks associated with unexpected events, such as sudden stops of the cage in the shaft.

The scientists also noted that proper quantification of all factors is essential, as any issues could lead to significant delays and cost overruns for the project. The successful test of lowering the heavy steel components moves the international collaboration closer to the installation of the DUNE detector. Once operational, neutrinos will be sent from Fermilab’s campus near Chicago, traveling 800 miles underground to DUNE’s large detectors at SURF . Scientists hope DUNE will provide a clearer understanding of how neutrinos behave, change states, and possibly offer insights into the origin of matter in the universe.