PASADENA--Steven Koonin and Ahmed Zewail of the California Institute of Technology have each been named recipients of this year's E.O. Lawrence Award by the U.S. Department of Energy.
The prestigious honor is given for exceptional contributions to the development, use, or control of nuclear energy. The award has been given since 1959 in memory of Ernest Orlando Lawrence, the Nobel Prize-winning nuclear physicist who invented the cyclotron.
Koonin, a theoretical nuclear physicist who also serves as Caltech's vice president and provost, and Zewail, a physical chemist who has pioneered the field of femtochemistry, will join four other Americans at the January 15, 1999 awards ceremony in Washington, D.C.
Bill Richardson, U.S. Secretary of Energy, commended Caltech for Koonin's and Zewail's advancements in nuclear science.
"I congratulate Caltech for having two winners," Richardson said. "This is only the second time in the award's 38 years that one university has produced two winners."
Koonin, 46, is particularly known for his development of an innovative computer technique for modeling nuclear shells. By using state-of-the-art parallel computers and a programming protocol known as the Monte Carlo technique, Koonin has improved the computational models of atomic nuclei for better and more detailed understanding of nuclear processes.
This work represents a major advance in nuclear theory by allowing the shell model to be used as a means of computing nuclear properties. The shell model is a microscopic theory of the structure of nuclei that assumes nuclear particles are more or less moving independently in a single, smoothly varying force field. Thus, the model provides a foundation for detailed understanding of nuclear processes.
However, depending on the number of nuclear particles and other factors, the shell model can be computationally difficult or downright impossible due to the huge amount of number crunching necessary. Koonin's approach sidesteps much of the mathematical complexity by using path integral methods combined with the Monte Carlo technique.
Koonin's work has had a broad impact on nuclear many-body physics, as well as on astrophysics in providing a greater understanding of how the heavier elements are cooked in the interiors of stars.
He is also widely known for his seminal work on pion interferometry. Pions are the lightest of mesons and the carriers of much of the nuclear force between nucleons (the components of the nucleus). Koonin's theory of quantum interference effects between emitted pions is one of the most important techniques for studying hot nuclear matter. The work has already been applied to the study of collisions between heavy ions at relativistic energies, and is focused on exploring the predicted phase transition of nuclear matter at densities and temperature similar to those soon after the Big Bang.
Zewail, 52, is the Linus Pauling Professor Chemical Physics and Professor of Physics at Caltech. Zewail has garnered international attention in recent years for the new and burgeoning field of femtochemistry, which allows molecular reactions to be viewed by using extremely short pulses of laser light. These pulses create stop-action images of individual atoms as they react and pass through transition states to final projects.
Zewail's methodology has made it possible to directly probe elementary dynamics at the most fundamental scale, and has given reality to the most central concept in the realm of molecular science--the transition state.
By providing an increase of nine orders-of-magnitude in time resolution, Zewail's contribution has been to allow the study of physical, chemical and biological events that occur on the femtosecond time scale, which allows the chemical bond to be viewed as it unfolds in real time.
The breakthrough research was made initially on elementary systems, opening up direct, real-time studies of quantum state-to-state rates, and energy redistribution in molecules. Also, the research has provided important junctions to theory and defined new concepts in dynamics.
The field of femtochemistry has been pursued by other investigators since Zewail began the pioneering work, and has already had an impact on chemical, biological, and medical research all over the world.
