At the border between Switzerland and France, the pristine Alps hide a world-shaking secret. In a 27-kilometer circling underground tunnel, scientists from SMU and other institutions are preparing for a subatomic demolition derby unprecedented in scale, scope and potential significance.
The Large Hadron Collider (LHC), which will power up for the first time in November 2007, can fling high-energy protons at speeds approaching light itself until they crash into each other, releasing even smaller bits of matter. When the largest particle accelerator ever constructed becomes fully operational, physicists will be able to recreate and record conditions at the origin of the universe. Scientists from SMU and more than 140 institutions and 38 countries will be on hand for research and discovery.
The field of particle physics – or the study of subatomic phenomena – has a long history, and its basic principles are well described in the Standard Model of Particles and Forces. During the past 20 years or so, however, “we’ve stopped understanding,” says Ryszard Stroynowski, SMU physics professor and LHC researcher. “Our theories have broken down. Usually when that happens, it’s not because the theories are wrong, but because we’re missing something.”
Astrophysical observations show that visible objects such as stars, planets and other entities reveal only a small percentage of the universe’s total mass and energy. “It’s possible there exists a different type of matter that we and our instruments don’t yet see,” Stroynowski says. “It’s also possible that we don’t understand anything. As scientists, we always keep that in mind.”
The answer to this and related questions may lie in the so-called Higgs mechanism, which suggests that particles in space acquire their masses by interacting with a field of unidentified matter – strongly if the particles are heavy, more weakly if they are lighter. Scientists have not yet proven the existence of a particle called the Higgs boson, the hypothetical “God particle” that may be responsible for that differentiation in masses, and physicists can only look for the Higgs boson in the scattering of subatomic particles released by smashed protons. The motivation for finding that particle is “getting to understand how our universe works,” Stroynowski says.
Enter the Large Hadron Collider, the result of an international collaboration led by the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. SMU’s contribution focuses on a component called ATLAS – at 46 meters long and 7,000 tons, the largest particle detector ever built. Stroynowski is U.S. coordinator for the Liquid Argon Calorimeter at ATLAS’ center, which will detect the high-energy postcollision debris that scientists hope will be the signature of the Higgs boson and other new discoveries.
The LHC project came to life in the void left by the cancellation of the Superconducting Super Collider (SSC), originally a project of the U.S. Department of Energy located near Waxahachie, Texas. The SSC, which began major construction in 1991 and brought Stroynowski and other experts to SMU, lost its federal funding in 1993. Today, the project is marked only by a vast and vacant underground tunnel where the world’s largest particle accelerator would have been. The LHC will power up at a time when “Superclyde” would have been online for at least five years. “But the questions are not going to go away just because politicians say so,” Stroynowski says.
After the SSC’s closing, the federal government provided U.S. physicists with funds and permission to participate in the European project. (SMU’s own LHC-related grants total nearly $9 million to date from various sources.) By August, the builders expect to close access to the experimental hall, a seven-story pit located 100 meters underground. After months of testing to ensure that the LHC’s systems work as intended, scientists should start taking experimental data within two years.
Each year, researchers hope to capture about 10 rare subatomic “events” (phenomena that occur at a single point in space-time, which are fundamental units of observation in relativity theory). Meanwhile, they will collect data on 40 million events per second. “And we have to make sure those interesting events occurred, not because somebody sneezed, but because they’re real,” Stroynowski says. “It’s unprecedented in the history of human data. This project pushes the limits of many fields beyond anything that has come before.”
To capture the information released when atoms collide, researchers from SMU’s Physics and Electrical Engineering Departments have built about 2,000 fiber-optic transmission links similar to the connection between a home computer and server – except they work at speeds 10,000 times faster. SMU scientists designing this technology include electrical engineers Gary Evans and Ping (Peggy) Gui and physicists Jingbo Ye and Robert Kehoe.
“In this area, SMU is known to be on a par with any other school in the country,” Stroynowski says. “Our Physics Department has brought the University international recognition, and it provides a fantastic training ground for graduate students.” Those students include Vitaliy Fadeyev (’00), now an adjunct professor at the University of California-Santa Cruz, who applied principles he used as an ATLAS researcher at Lawrence Berkeley National Laboratory to help create a new method for restoring and preserving mechanically recorded sound. And projects such as ATLAS reward support for basic research in the natural sciences, Stroynowski says. “This is an adventure of discovery. We don’t always succeed – that’s the nature of adventure. But there is no way to express the excitement for all of us involved.”
— Kathleen Tibbetts