Four University of Rochester scientists from the fields of physics, optics, and mechanical engineering were elected fellows of the American Physical Society in the latest balloting. Riccardo Betti, Robert W. Boyd, Thomas H. Foster, and Paul L. Tipton received the honor, which is given to less than one-half of 1 percent of the membership of the society each year.

Betti, associate professor of mechanical engineering and physics, and scientist in the Laboratory for Laser Energetics, was recognized for his seminal contributions to the analytic theory and understanding of the ablative "Rayleigh-Taylor instability" in inertial confinement fusion. This approach is now seen as the most promising method for controlled thermonuclear fusion. In particular, Betti's research focuses on the hydrodynamic stability of laser-driven implosions.

The society also cited Betti's work on Alfven eigenmodes in magnetic fusion energy research. Alfven eigenmodes are waves that can become unstable in a fusion plasma, preventing the onset of thermonuclear ignition. A faculty member at Rochester since 1991, Betti received his doctoral degree in nuclear engineering from the Massachusetts Institute of Technology in 1992.

Among its 2001 fellows, the society honored Boyd for contributions to the understanding of the nonlinear interaction of light with matter. On the faculty of the Institute of Optics since 1977 and a professor of optics since 1987, Boyd is a fellow of the Optical Society of America and is the past chair of the Laser Science Division of the American Physical Society. Recently, he was named the M. Parker Givens Professor of Optics.

His research interests include studies of the nonlinear optical properties of materials, nonlinear optical interactions in atomic vapors, optical phase conjugation, and the development of new laser systems. The holder of four patents, Boyd received his doctorate in physics in 1977 from the University of California at Berkeley.

Associate Professor Foster, whose research involves optical methods in cancer treatment and diagnosis, was acknowledged by the society for his unique and successful applications of physical concepts to the understanding and advancement of magnetic resonance imaging, photodynamic therapy, and diffuse-light optical studies of tissues.

Foster, who holds University appointments in the Department of Radiology at the School of Medicine and Dentistry, the Department of Physics and Astronomy and Institute of Optics in the College, and the James P. Wilmot Cancer Center, earned his doctoral degree in physics from the University of Rochester in 1990.

Tipton, who is professor of physics, received recognition from the society for playing a lead role in the discovery and study of the top quark, and for his part in the construction of the SVX detector used in that discovery. In 1995, Tipton was among the physicists who confirmed the existence of the top quark, a subatomic particle that is so massive it may be the final key to understanding the fundamental nature of matter.

He earned his doctoral degree in physics from the University of Rochester in 1987 and joined the Rochester faculty in 1991. Tipton's research interests are concentrated in the field of experimental high energy physics with a focus in heavy quarks.