UT Researchers Helped Convert Light Into Matter (425)

KNOXVILLE, Tenn. — When scientists recently converted light into matter, four researchers from the University of Tennessee were part of the 20-person team that accomplished the feat.

Dr. Bill Bugg, professor; Steve Berridge, engineer; Dr. Achim Weidemann, research associate; and Dr. Konstantin Shmakov, research assistant — all of the UT-Knoxville physics department — were involved in the experiment at the Stanford Linear Accelerator Center in California.

 Although technology for the experiment didn’t exist until recently, Bugg said the small size of the research team reminded him of an era when science was practiced on a smaller scale.

“The project was tiny by recent standards,” Bugg said. “We are high energy physicists and most of our experiments involve the collaboration of hundreds of people.”

 Almost on one hand Bugg counted the senior scientists involved — Tennessee, one; Princeton University, two; University of Rochester, two; and Stanford University, one.

 “Most of the others were graduate research assistants or associates,” Bugg said. “It was a wonderful experience for them and great fun for all of us.”

 Bugg said the researchers created matter from light by propelling electrons through a linear accelerator head-on into a photon-packed beam of laser light.

The resulting collision, repeated thousands of times, produced more than 100 positrons — tiny bits of matter, measurable only by instrument — over the course of the experiment, Bugg said.

The results were announced in the Sept. 1, 1997, issue of “Physical Review Letters.”

Long the subject of science fiction lore,the conversion of light to matter was predicted by scientists in the 1930s. The reality was more than 65 years in coming.

“Lack of adequate laser technology was probably the limiting factor,” Bugg said. “It was not until five or six years ago that lasers became available with the kind of power needed to do this experiment.”

 Although the successful experiment has attracted world-wide media attention, particularly in the scientific press, Bugg is philosophical about the results.

“Matter was created that never existed, but from the perspective of basic physics, the results were expected,” Bugg said.

The next step in the project will be to try out a new, more advanced laser that should provide better results than the original equipment, Bugg said.

 With the new laser, the scientists hope to create more positrons with fewer collisions. Practical applications for the new discovery are limited, Bugg said.

 “In this process the way we make positive electrons may be particularly useful in new, higher energy accelerators,” Bugg said. “That’s a major possibility, but whether you call that a practical application probably depends on your point of view.”

 Contact: Dr. Bill Bugg (423-974-3342)