Physics turned on its ear catches attention at Fermilab
By Jenette Sturges firstname.lastname@example.org September 24, 2011 6:22PM
Stripe the gremlin watches over the two buttons that Fermilab staff will use to initiate the shutdown of the Tevatron later this week. | Steven Buyansky~Sun-Times Media
Updated: November 30, 2011 12:38AM
BATAVIA — The cafeterias, control rooms and elevators at Fermi National Accelerator Laboratory buzzed with excitement Friday morning.
That’s because news of a collision halfway around the world — at CERN, Fermilab’s newer, bigger, European counterpart — could, if true, turn the world of particle physics on its head. European physicists announced they’d measured a neutrino particle shot from the Franco-Swiss border to Italy traveling faster than the speed of light.
“The most likely thing is that it’s a mistake,” said Don Lincoln, Fermilab physicist. “But they tried to destroy the finding, did everything they could to rule it out.”
Lincoln isn’t postulating out of jealousy. Far from it. Though he’s a Fermilab scientist who has worked on the lab’s DZero experiment on the Tevatron particle accelerator for years, like many of Fermilab’s scientists, he’s shifted his work to examining the data pouring out of CERN. He works in Fermilab’s Remote Operation Center, modern science’s most important remote control, which allows physicists in Batavia to initiate particle collisions in Europe.
But while CERN and its Large Hadron Collider will get much of the credit for discoveries like this faster-than-light neutrino, over the next decade that work will be built on the legacy of one machine, buried under a prairie grass berm, right here in Batavia, that will cease to operate on Friday.
The Tevatron Era
That machine, the Tevatron, is a four-mile circuit along which supercharged particles reach incredible velocities — more than 99 percent the speed of light — and temperatures not seen since mere moments after the big bang that some theorize marked the beginning of the universe.
When the particles collide, the protons break apart, revealing the subatomic particles upon which all matter is built. Beams collide at two different detectors, called CDF and DZero, where physicists have been smashing particles together in search of new clues to the nature of the universe since 1985.
“We will really miss the Tevatron. It’s been the machine that’s defined the laboratory for so long,” said Roger Dixon, head of Fermilab’s accelerator division. “But now we have to move on and do something new, something better, keep pushing back the frontiers of science.”
The Tevatron is a direct ancestor of CERN’s Large Hadron Collider, and for more than two decades was at the frontier of particle physics, responsible for hundreds of scientific papers, dozens of Ph.D.s, and a few discoveries so notable that even those without so much as a B in high school physics can remember them. The particle accelerator, and its lab of hundreds of scientists, engineers, and computing professionals, and about two dozen bison, are so entrenched in the Fox Valley there’s even a beer — Two Brothers’ Atom Smasher — named in their honor.
“This was the first superconducting accelerator ever built, and that was a major thing,” said Dixon. “But the real legacy is all the physics that has come out of this ... things that people 500 years from now would still be reading about.”
Most famously, experiments on the Tevatron led to the discovery of the top quark.
Quarks are particles that combine to form the protons and neutrons that make up all the universe’s matter. Scientists at Fermilab not only found the particle in 1995, but have been able to determine the top quark’s mass and two distinct ways it is produced.
That major discovery, however, is just one of the thousands of findings that have emerged from experiments on the Tevatron. Fermilab physicists have published, on average, one peer-reviewed paper a week from each experiment since 1985.
But ask a physicist how these hundreds of discoveries will benefit society, and they’ll all say pretty much the same thing — that’s not really their department.
“We are studying pretty fundamental things,” said Dmitri Denisov, physicist on the DZero experiment. “What is the immediate application of the fundamental laws, that’s not the goal of our research because we’re trying just to find these laws. There are many spinoffs, but that’s not the goal.”
That doesn’t mean there isn’t a long list of modern conveniences that could be called Tevatron by-products.
Medical centers use much smaller, less powerful versions of the particle accelerator to produce X-rays and treat cancer. PET scans and MRIs are derivatives of Tevatron technology. Electricity flows along lines of superconductive materials first designed for the Tevatron.
And yet, despite the major leaps science has made as a result of the Tevatron, the U.S. Department of Energy announced in January that it was cutting funding to the accelerator program, denying Fermilab its request for $100 million to operate the Tevatron another three years.
So on Friday, after 26 years of uncovering the universe’s smallest-scale mysteries, the Tevatron will, with the push of a couple buttons, shut down for good.
‘Everything has an end’
Each of Fermilab’s nearly 1,000 scientists and engineers possesses a fond attachment to the machine. Many of them first came to Fermilab decades ago as a doctoral students, bunking in on-site trailers for the privilege of working with the machine that promised to help scientists see into the past, to mere milliseconds after the beginning of the universe.
But most will admit that shutting her down is simply a matter of moving resources to the new frontiers of physics.
That frontier is now at CERN, where the Large Hadron Collider has stolen the spotlight. Last year, the 17-mile track 500 feet below the surface of the Alps near Geneva set the record for the highest-energy man-made particle collision, though it still operates at only half the energy level for which its designed.
By comparison, the large red button that will shut down the Tevatron next week looks downright retro.
“Everything which has a start has an end. We extracted everything we could from this excellent machine, and recorded billions of collisions,” said Denisov.
“We’ve basically reached a plateau in Tevatron’s performance. At this point, the machine is rather old, so upgrading it is taking a Ford Model T and trying to put new tires on it.”
New frontiers of physics
Since the public learned of CERN and its Tevatron-eclipsing capabilities, speculation spread about whether Fermilab would shutter, leaving only the roaming buffalo behind in the vast expanse of prairie. Rather, scientists see their work on the Tevatron as a stepping stone to myriad projects that will keep the Fermilab campus humming for decades.
For one, there’s a difference between smashing particles and understanding the reams of backlogged data that those experiments produce.
“For us, life will not change drastically,” said Denisov. “While we will not be taking shifts, we will still sift through the data and be publishing papers.”
In the last few days of the Tevatron’s operations, physicists continue to chase the Higgs boson, the hypothetical particle that would help solve inconsistencies in the standard model of physics. Even if Fermilab’s physicists aren’t able to produce the particle before Friday, they’re hoping they’ll be able to take their data to the Large Hadron Collider and point CERN’s scientists to it, either confirming or disproving the existence of the particle by the end of the year.
“If the Higgs boson exists, the accelerator here at Fermilab has been working on it here for many years and has been able to rule out certain masses,” said Lincoln. “Now you combine the Large Hadron Collider and Fermilab’s information together and you rule out a large range. Looking for the Higgs boson is probably the first big thing we hope to weigh in on.”
But despite the bubbling excitement that comes with being on the verge of such a major discovery in the energy frontier, physicists view smashing together heavy particles as just one of three frontiers that, when overlapped, give humanity an understanding of how the world works.
Across a field of prairie grasses in a smaller lab, physicist Tom Diehl has turned his attention from the universe’s tiniest particles to its largest celestial bodies.
“We believe it’s the world’s largest digital camera,” said Diehl, pointing to camera pieces that will be added to a telescope high in the Chilean Andes. The project, called the Dark Energy Survey, stands at the forefront of physics’ cosmic frontier, and uses specialized chips originally designed for the Tevatron.
“Because of our experience in building silicon strip detectors for high energy physics experiments like in Tevatron, we were pretty sure we’d be able to handle the technology to do this,” said Diehl.
When the 570-megapixel camera begins capturing light in June 2012, it will be able to photograph huge expanses of space — about a quarter of the southern hemisphere in just 525 nights — and capture celestial objects that are further and dimmer than any other telescope. That will help physicists understand the dark energy that makes up about three-fourths of the universe.
The future of Fermi
But the future of Fermilab will not be anything big. Rather, if America can’t have the biggest particle accelerator, Fermilab scientists are hoping it will have the fastest.
Already, physicists like Peter Shanahan are working on what Fermilab sees as its future: the intensity frontier — studying particle interactions that rarely happen by ramping up the frequency of those interactions. His experiment, NOvA, will build on previous Fermilab experiments, sending an underground beam of neutrinos to a particle detector on the Minnesota-Canada border.
“Now we’re looking specifically for muon neutrinos becoming electron neutrinos. That’s important because that’s governed by physical parameters that are the biggest mysteries right now,” said Peter Shanahan. “Once we establish that effect, it might be possible for us to ... explain how we ended up in a world where there’s really only matter, even though we know anti-matter exists.”
But the next major goal in the intensity frontier would require a new three-megawatt high-intensity proton accelerator — one that creates 1,000 times the collisions of the Tevatron. It’s been given the ominous-sounding name Project X, and if they can build it, physicists are hoping they’ll be able to find rarely occurring particle interactions.
“There is a whole other area of physics where we don’t depend on having the greatest amount of energy but the largest number of particles,” said Oddone. “And that’s where the facilities at Fermilab will go.”
But that would require a feat more challenging than breaking the world’s fastest neutrino record — securing serious federal dollars from a tight-fisted Congress.
But according to Oddone, solidifying Fermilab’s stature on the physics frontiers isn’t just about one new experiment.
“It really boils down to a question of whether we are a nation that explores nature in this very fundamental level. There are many mysteries we don’t know where it’s going to take us,” said Oddone. “What we are trying to do is to play a role in this global context of solving these very fundamental mysteries. I think to retreat from that as a nation would be a very bad thing to do, because this spirit of inquiry is really what drives the development of society.”
About 100 jobs will ultimately be affected by the shutdown of the Tevatron. Of those, about 60 scientists will head into early retirement. Others will be reassigned to different experiments around Fermilab or find positions at other laboratories in American industry, or for foreign governments.
But while the era of the Tevatron will end, Fermilab will continue on, so long as the federal government continues to see value in physics exploration.
“Our principal drive is to contribute in a significant way to answering those mysteries, and the Large Hadron Collider is not going to answer all those mysteries,” said Oddone. “As a matter of policy, we need an understanding that there is role in studying fundamental physics and probing these very deep questions. Asking these very profound questions inspires the public, inspires our students. It’s very important for the country.”
On Wednesday, U.S. Representatives in the Science, Space and Technology Committee, including Randy Hultgren, R-14th, and Judy Biggert, R-13th, will meet at Fermilab for a roundtable on the future of the lab’s research programs, including what it would take to get Project X up and running. In March, Hultgren has lent his support for Fermilab, but fell short of saying the lab would not face any short-term cuts.
Meanwhile, computer screens in Fermilab’s dark, futuristic-looking Remote Operations Center, display realtime results of more particles colliding deep in the Franco-Swiss Alps. Don Lincoln and other members of his team will parse some of the results out to American universities. But most of it they’ll sift through themselves, on the hunt for the next big discovery.
As for the Tevatron itself, after Friday, workers will begin dissembling the three stories of concrete encasing the machine. In six months’ time, sections will be opened to the public so they can view for themselves the marvels hidden under the prairie for 26 years.