Costs balloon for U.S. particle physics megaproject

The gigantic new experiment on which the future of U.S. particle physics depends is far overbudget and years behind schedule, and a leadership shake-up at Fermi National Accelerator Laboratory (Fermilab), the experiment’s host, is adding to the turmoil. The Long-Baseline Neutrino Facility/Deep Underground Neutrino Experiment (LBNF/DUNE), a massive effort to probe nature’s most elusive particles, is now expected to cost
$3 billion, 60% more than the preliminary estimate, and construction has slipped 4 years, with first data expected in 2029. The rising costs obligate the Department of Energy to reassess the project’s design, although DOE officials say they have no plans to downsize it.

“DOE is not planning to implement any scope reductions that would sacrifice the science reach of the experiment,” Jim Siegrist, DOE’s associate director for high energy physics, wrote in an email to Science. Some physicists hope DOE will get the money to cover the overruns from a $3.5 trillion spending plan to reinvigorate the economy, now being debated in Congress. The House of Representatives version of that spending package contains $1.3 billion for LBNF/DUNE. But passage is far from certain.

LBNF/DUNE would fire barely detectable particles called neutrinos from Fermilab, in Illinois, to an underground particle detector 1300 kilometers away in an abandoned gold mine in South Dakota. Neutrinos come in three types—electron, muon, and tau—which morph into one another as they zip along at near–light speed. LBNF/DUNE aims to put the theory of such neutrino oscillations to the definitive test and look for a difference in how neutrinos and antineutrinos oscillate that might help explain how the universe generated more matter than antimatter.

The budget overruns are the latest twist in a 20-year quest to build an enormous neutrino experiment deep in the Homestake Mine, where 1.5 kilometers of rock would block inference from cosmic rays. In 2001, physicists proposed that the National Science Foundation build a vast underground lab at Homestake, but 10 years later NSF’s governing board balked. DOE quickly affirmed it wanted the neutrino experiment, but only at half of the $1.9 billion it was then estimated to cost. Physicists kept the project big by inviting international contributions, and in 2013 CERN, the European particle physics laboratory, said it would take part.

On 5 November 2015, DOE approved a conceptual design for the two-part experiment, along with a preliminary cost range of $1.26 billion to $1.86 billion. LBNF includes the buildings, a new neutrino beam at Fermilab, the experimental halls in South Dakota, and the vast refrigerated tubs to hold the neutrino detectors. DUNE consists of just the detectors, including one in South Dakota holding 70,000 tons of frigid liquid argon, and a smaller one at Fermilab to monitor the outgoing beam.

Approval to build the detectors is at least 1 year away, but construction of the facilities began in Illinois in 2019 and South Dakota in 2017. In May, workers tested the conveyor system that will haul 800,000 tons of rock out of the mine. Several factors have driven the steep rise in costs, Siegrist says: The mine’s aging infrastructure needed upgrading, installing the delicate detector at Homestake will be more difficult than anticipated, and the smaller detector at Fermilab needs to be more sensitive than originally envisioned. Excavation and the construction of buildings account for roughly $2 billion of the cost, multiple sources say.

DOE’s budget request for fiscal year 2022, which begins 1 October, also notes that international contributions have been lower than expected. Still, international partners are paying for half of the first two of an eventual four modules in the Homestake detector, and CERN will build the refrigerators for those two, notes Stefan Söldner-Rembold, a neutrino physicist at the University of Manchester and cospokesperson for the 1300-member DUNE team.

The overrun in the preliminary cost is so large that DOE rules require officials to rethink the project’s conceptual design. But they seem reluctant. Once new cost estimates are finalized, Siegrist says, “DOE would reaffirm the scope of the project and approve the new cost and schedule ranges.” That is, DOE envisions maintaining the design and changing the cost, not the other way around.

Within a year that flexibility will vanish, as project leaders must deliver their final detailed costing and construction schedule. Given the work already done and the problems solved, researchers are confident they can formulate a reliable baseline, Söldner-Rembold says. “The difference is that now, everything is on the table,” he says.

DOE’s tack means LBNF/DUNE will need more money, which physicists hope will come from the spending package. “Having something really excellent that is important for the long-term competitiveness of the United States as an intellectual powerhouse and not finding that money seems really tragic,” says Patrick Huber, a theorist at Virginia Polytechnic Institute and State University.

Representative Bill Foster (D–IL), a former Fermilab physicist who serves on the House science committee, says he’s confident the spending plan will pass and will include funding for LBNF/DUNE, as U.S. particle physicists made the project their priority in a 2014 long-range plan. “When a project has the full support of the scientific community, if there are some costs increases, it’s a mistake for Congress to cut it off,” Foster says. If the plan does not pass, DOE may have to cut other high energy physics programs to support the more expensive LBNF/DUNE.

Fermilab may have to push ahead without its current director, Nigel Lockyer, who on 10 September announced he will step down once his replacement has been found. Lockyer declined to discuss his reasons, but DOE appears to want to shake up the lab’s management. In a letter to LBNF/DUNE’s international collaborators, Siegrist and Stephen Binkley, acting director of DOE’s Office of Science, say the office “sees this change as an opportunity to reinvigorate all Fermilab efforts.”

DOE officials and researchers credit Lockyer for guiding Fermilab through tough times. He arrived in 2013, 2 years after its flagship atom smasher, the Tevatron, shut down, ceding the 2012 discovery of the famous Higgs boson to CERN’s Large Hadron Collider. Lockyer rallied Fermilab and U.S. physicists around the neutrino program, says Michael Turner, a cosmologist at the University of Chicago, who helped recruit Lockyer. “He’s got us set up to lead in neutrinos and do the biggest project DOE has ever done.”

source: sciencemag.org