When scientists at the Fermi National Accelerator Laboratory announced last month that they may have discovered a new elementary particle or fundamental force of nature, it was likely the swan song of the lab’s Tevatron accelerator, once the most powerful atom-smasher in the world.
That title now belongs to the Large Hadron Collider in Switzerland, which is designed to generate seven times Tevatron’s peak energy. Scientists hope the $10 billion accelerator will take them closer to understanding both the micro world of subatomic particles and the origins of the universe and its likely future.
With the 25-year-old Tevatron scheduled to shut down in September, the Batavia laboratory, one of the Chicago area’s premier research institutions with a budget of almost $400 million, will narrow its focus to less expensive experiments as it explores other uncharted areas of physics.
“We’ve delimited the field in which we’re going to build facilities—they’re much more realistic, said Fermilab director Pier Oddone. “They’re smaller-scale.”
With the accelerator shutting down and the workload shrinking, Fermilab is expected to cut about 5 percent of its workforce of 1,900 jobs over the next few years.
Much of Fermilab’s past work involved whirling protons and antiprotons at nearly the speed of light around its circular accelerator toward a collision that simulated the high-energy conditions of the early universe. Scientists study the spray of subatomic particles given off by the impact in hopes of observing new ones. The top quark, a building block for other subatomic particles, was discovered at Fermilab in 1995.
Because the Large Hadron Collider can create much more energetic collisions, scientists on the cutting edge of physics have taken their hunt for the next batch of elusive particles to Switzerland.
“High energy physics has ceded leadership to Europe,” said Eric Isaacs, director of Argonne National Laboratory, a facility known for its work in energy conservation and high-speed computing.
Doug Glenzinski, head of the Collider Detector at Fermilab, said about a third of the 600 professors, students and staff working on his detector have left over the past three years, and many academics now direct their graduate students to the LHC, not Fermilab.
“The number of people who are involved in experiments here is noticeably down,” Glenzinski said. “You can just see that the place is less crowded.”
Fermi’s future experiments will focus on creating the most particles, not necessarily the most energetic ones. Scientists plan to create dense, relatively low-energy beams of neutrinos—little understood particles that have almost no mass, no electrical charge and other quirky properties.
“After photons,” the particles responsible for light, “neutrinos are the most pervasive particles in the universe. You have billions passing through you all the time, but because they’re so elusive, we don’t really understand how they behave,” Oddone said.
Physicists think neutrino experiments could help explain the very existence of the universe—after the Big Bang, scientists believe there were equal amounts of matter and antimatter, but now there is far more matter.
“The way the mathematics works out, neutrinos have to have very heavy partners, which were created in the early universe, but decayed away,” said Milind Diwan, of Brookhaven National Laboratory. These heavy partners may have decayed asymmetrically—creating more matter and less antimatter. “Neutrinos are like an imprint we have access to.”
Fermilab has been studying neutrinos for more than a decade and has more than half a dozen additional projects in various stages of development, including one that would create the world’s most intense neutrino beam. That project, the Long Baseline Neutrino Experiment (LBNE), is still in the design phase, but if approved by the Department of Energy is expected to start collecting data by 2020. It is expected to cost about $1 billion, said Diwan, who is a leader on the experiment.
But the emphasis on neutrino research may not be able to sustain the wide variety of physics Fermilab is used to. Ed Blucher, chairman of the physics department at the University of Chicago, said experiments like the LBNE will primarily study just a handful of questions.
“The big collider experiments had hundreds of researchers who could go off and study a piece of physics they were interested in,” said Blucher, who worked at Fermilab in the mid-1990s. “These will be very focused experiments, with a lot of effort to measure one or two parameters.”
Architects of the neutrino experiments agreed that their work will be narrower than the Tevatron’s. “It’s just a different way of doing science than they’re used to,” said Bob Svoboda, a physics professor at the University of California-Davis and one of the LBNE leaders.
But Svoboda rejected suggestions that neutrino experiments would not create as much scientific output as the Tevatron. While the Tevatron had larger teams, he said, the smaller neutrino experiments won’t have to wait to find the subject of their study.
“There’s a difference between doing lots of studies that may look for some hypothetical particles, and actual discoveries,” Svoboda said. “In our case, we know neutrinos exist. We want to find out why they behave like they do.”
Diwan, of the Brookhaven lab and co-leader of the experiment, downplayed the differences between neutrino and accelerator research. Even though neutrino physicists will eventually outnumber those working on atomic colliders, he said he didn’t expect much to change at Fermi.
“Culturally, it’s not going to be different,” said Diwan, who has worked at Fermi in the past. “It’s not like all of a sudden we’re going to be shooting rockets instead of particles.”
