Accelerating Into Physics

Jefferson Lab researchers take results public today

The Thomas Jefferson National Accelarator Facility makes its formal debut in the physics world today, as scientists present results from the first round of accelerator experiments.

The $600 million lab began doing science in November 1995. Researchers have shared their results informally with colleagues, but today's event in Washington, D.C., will be the first major pubic presentation, said Nathan Isgur, the lab's top theoretical physicist.

"It's kind of exciting," Isgur said. "Our first real stuff."

Four scientists and a dozen graduate students are scheduled to present their work at a program sponsored by the American Physical Society and the American Association of Physics Teachers. All their experiments took advantage of the unique continuous electron beam produced at the Jefferson Lab.

Other nuclear accelerators produce powerful electron beams, but in bursts that make some nuclear physics experiments difficult. The Jefferson Lab is the first to produce a continuous beam that allows more precision and enables researchers to more easily examine the tiniest parts of the atom.

The way Jefferson Lab scientists put it: Other accelerators "smash" atoms, theirs dissects them.

"You could not do these experiments before Jefferson Lab," said Keith Baker of Hampton University, one of the researchers speaking at today's meeting.

Baker led a team of researchers who used the continuous beam to create and explore subatomic particles called kaons. They aimed the high-energy electron beam at a hydrogen atom's proton, which is made up of three smaller particles called quarks. The result is a two-quark particle called a kaon.

Once produced in the laboratory, an individual kaon exists for only a tiny fraction of a second, but it's long enough for the lab's sophisticated detectors to analyze them. Baker estimates his team created several hundred thousand kaons over a month's time last fall.

Other accelerators are capable of producing kaons, but they tend to overwhelm the detectors with other subatomic particles, making it nearly impossible to pick out the kaons, Baker said.

"We're looking inside this thing better and farther than at any time in mankind," he said.

While breaking new ground, the first experiments at Jefferson Lab have been relatively modest, as scientists gradually break in their machine, Isgur said. "With any new equipment, you don't attempt the most difficult experiments first," he said.

Still, Isgur said, the experiments met their scientific goals, and the accelerator and detectors performed better than expected. The experiments also produced the raw material for 16 graduate student dissertations, said Rolf Ent, a Jefferson Lab researcher who will also present results from an experiment today.

"That's something all of us are pretty proud of," Ent said.

The research presented today won't radically change people's lives or produce new consumer products. Not anytime soon, anyway. The Jefferson Lab was built to answer fundamental questions about the basic building blocks of the atoms, Isgur said.

"It's too early to tell whether we'll be able to make practical use of this fundamental knowledge," he said. "We'll learning about how the world works."

Isgur likens the work at the Jefferson Lab to the initial atomic theories of the 1930s. That research eventually led to nuclear power, nuclear weapons, new medical techniques, lasers, computers and transistors, Isgur said.

"In 1930, they didn't know where their understanding would lead, but it led lots of places," he said.

Jefferson Lab officials are also quick to point out that the technology used in building the accelerator is helping create a new type of laser that has drawn interest from several companies and the Navy. The free-electron laser will be ready to shine its first beam at the Jefferson Lab in about a year, Isgur said.

Still, said Ent, it's important to remember that some of the research at the Jefferson Lab may never have a practical application.

"It stimulates the mind," he said. "It's like art. It's not always true there will be a technical spinoff."

Joining Baker and Ent in Washington will be Brad Filippone of the California Institute of Technology and Haiyan Gao of the Argonne National Laboratory in Illinois, two outside researchers who did experiments at the Jefferson Lab.