Arts and Science physicists conduct experiments from 4,600 miles away.
To the casual observer glancing through the glass windows, the room in Stevenson Center could be just about any on campus. Flat-panel displays hang in an organized cluster, covering most of three walls, emitting a gleam of red or green, depending on the day.
But the room is much more than a quiet computer lab. Instead, it is a window to the very forefront of modern physics, allowing Vanderbilt University researchers to transport half a world away to the border of Switzerland and France, where collisions of protons and heavy ions occur at nearly the speed of light.
The Stevenson facility is one of eight virtual control rooms in the United States that collect data from experiments at the Large Hadron Collider (LHC) outside Geneva, Switzerland. For most of the year, physicists study the results of collisions of protons that occur in the vacuum-sealed chambers 50-175 meters underground. One month each year, the focus is on heavy ions.
Each collision generates mountains of data and, as a Tier 1 computing center for the project, Vanderbilt plays a key role in collecting and storing the data and disseminating it to thousands of other researchers around the world. Vanderbilt also took a lead role in creating the Compact Muon Solenoid (CMS) experiment, one of two main particle detectors in the LHC.
“People will say, ‘You’ve got 2,000 people on this experiment; what can one group [Vanderbilt] matter?’” says Victoria Greene, professor of physics and senior associate dean of graduate education, College of Arts and Science. “You’re developing a reputation with these 2,000 people. There are entire research areas where the annual conference is less than half that. This is significant.”
Astonishing Results, Astonishingly Fast
Since the collider beam was first turned on in March 2010, it’s already yielded significant results. None has gained more attention than results indicating that scientists are getting closer to discovery of the Higgs boson, which could help explain why particles have mass. The CMS team and another team, Atlas, completed “astonishingly fast analysis of this data,” Greene says. “Neither result is big enough to reach the level needed for a discovery and it seems clear that we will need at least another year’s worth of data.”
While finding the elusive Higgs boson—sometimes called the “God particle”—may be one of the major goals of the LHC, it is far from the only research that’s being conducted. Greene, Professor of Physics Charles Maguire and Professor of Physics Julia Velkovska received one of Vanderbilt’s own IDEAS grants to study jet shapes in heavy ion collisions. Associate Professor of Physics Will Johns performs research that makes him the “go-to person for the pixel tracking detectors, the fine tracking detectors at the heart of CMS,” Greene says.
Vanderbilt plays a key role in collecting and storing the data and disseminating it to thousands of other researchers around the world.
“All top physics departments have a presence in fundamental physics like this,” Greene says. “Ultimately, you need to be able to understand matter in its essence. It’s also attractive to students. As soon as LHC turned on, we had more students than we knew what to do with. Students want to work at the energy frontier and that’s something we can provide.”
To be sure, there are modern-day challenges, such as the weekly meetings that alternate between convenient times for those in Europe and for researchers in the States. That may mean that a Vanderbilt postdoctoral researcher like Monika Sharma makes a presentation at 2 a.m.—ensuring that her web camera is turned off so no one can see that she’s ready for bed. It also requires physics graduate student Eric Appelt to be available any time the green on the screen turns red, indicating that there’s an issue with the quality of the data that’s being sent. He has five minutes to respond to avert a flurry of panicked calls from researchers from around the world, concerned about data being lost.
“As soon as LHC turned on, we had more students than we knew what to do with. Students want to work at the energy frontier and that’s something we can provide.”
“We actually rotate being on call,” Appelt says. “There is actually a human being looking at these all the time. If one of these turns red, there’s someone somewhere in the world with a beeper.”
While the LHC is itself a marvel, the sheer volume of data that it creates brings both challenges and potential. In December 2010, the heavy ion collisions generated 30 million separate events, all of which had to be analyzed. In all, the LHC provides enough data to fill 1.7 million dual-sided DVDs each year; Vanderbilt has devoted more than 1,000 computer cores to store the information.
“It’s a different scale and a different amount of data that is being collected,” Sharma says. “There’s definitely more pressure with it as we’re managing the needs of the Tier 2 centers and doing the physics analysis ourselves. It’s really keeping your feet on two different poles and trying to manage.”
But as the research continues to yield impressive discoveries, the juggling has proven productive.
“In this field it is especially important to choose your experiments wisely, because the experiments take such a long time to plan, build and conduct that you can’t work on very many in your career,” Greene says. “Tantalizing results like these underscore that fact that we physicists chose well when we joined CMS, and Vanderbilt chose well in supporting our efforts.”
photo credit: John Russell