The Long Baseline Neutrino Experiment's design includes a neutrino detector in the Sanford Underground Research Facility, formerly Homestake Mine, in South Dakota. Image: Jennifer Snyder
Neutrino physicists in the U.S. have begun to regroup after a disappointing setback last week, when they learned the Department of Energy would not support the budget of a major proposed experiment.
The silver lining, as they see it, is that they have the chance to reevaluate their plans and find a path forward. DOE officials asked Fermi National Accelerator Laboratory to study ways to make the costs of the Long Baseline Neutrino Experiment more manageable, such as dividing its construction into stages or working with an existing neutrino beam.
“On the one hand, we’re of course disappointed that we cannot do the whole experiment at once,” said Pier Oddone, director of Fermi National Accelerator Laboratory. “On the other hand, we’re encouraged. So long as we can get to the ultimate physics goals, we are happy.”
LBNE scientists hope to explore unanswered questions about neutrinos, some of the most abundant but least understood particles in the universe. Neutrinos have been surprising physicists since they were first discovered in 1956. Not only did they unexpectedly turn out to have mass, contrary to predictions from the Standard Model of particle physics; scientists also discovered that they mysteriously morph from one type to another mid-flight.
The LBNE collaboration includes more than 300 scientists and engineers from 51 institutions in the United States and 10 institutions in India, Italy, Japan and the UK. Current plans would place the larger of LBNE’s two neutrino detectors underground in Homestake Mine in South Dakota, now the Sanford Underground Research Facility, which is managed by the South Dakota Science and Technology Authority and Lawrence Berkeley National Laboratory.
DOE Office of Science Director Bill Brinkman said in a letter that DOE could not sustain the project’s annual construction costs. At their highest, they could reach an annual cost of more than $200 million, about a quarter of the allotment for high-energy physics in the president’s 2013 budget request.
But Brinkman expressed support for the experiment’s goals, writing, “This decision is not a negative judgment about the importance of the science, but rather it is a recognition that the peak cost of the project cannot be accommodated in the current budget climate or that projected for the next decade.”
Physicists designed LBNE to learn about how neutrinos are organized by mass, to test whether neutrinos act differently than antineutrinos, and to explore whether there are undiscovered types of neutrinos not described in the Standard Model. With the same apparatus, they could also search for proton decay – thus far unobserved in nature – which could tell scientists about the validity of grand unified theories of particle interactions. They could also learn more about what goes on in the core of a collapsing star, if a supernova were to explode in our galaxy during the experiment’s run.
“DOE is looking for a way to do this program,” said LBNE Program Manager Jim Strait.
So are neutrino physicists. This month, LBNE scientists will take suggestions from the community and study the scientific potential of their options. By summer, they hope to bounce back with a new plan.
