Radyushkin's work falls in the field of quantum chromodynamics (QCD). QCD is a fundamental theory that addresses the underlying structure of nucleons -- the protons and neutrons that makeup the nucleus of the atom -- in terms of their more elementary constituents. Nucleons are made up of quarks and gluons, elementary particles referred to as partons. Generalized parton distributions are functions that physicists can use to map out the location and momentum of the quarks and gluons inside a nucleon.
The functions are being developed with information obtained from electron-nucleon collisions. In this process, physicists use an accelerator to propel a beam of electrons to speeds approaching the speed of light. When these electrons strike a target, many collide with particles in the nuclei of atoms. Each collision results in an array of scattered particles. GPDs can be applied to those collisions that result in a scattered electron, proton and a photon, an effect called "deeply virtual Compton scattering." Applying GPDs to this scattering pattern reveals information about the structure of the nucleon before the collision. The result is an essentially holographic picture of the inner structure of the nucleon.
"GPDs allow scientists to use an accelerator to get the effective resolution power of an electron microscope and an X-ray installation," Radyushkin says. He says this work has opened a new field of scientific investigation that allows the measurement of the properties of protons and the comparison of these measurements with theoretical predictions. Experiments measuring and testing GPDs are conducted at Jefferson Lab, which is funded by the Department of Energy's Office of Science, and the testing of these methods are an essential part of Jefferson Lab's present and future physics program.
Radyushkin completed his pre-doctoral work at Moscow State University in the Russian Federation, and received his Ph.D. in physics there in 1978. He is a permanent staff member of the Laboratory of Theoretical Physics in Dubna, Russia. He came to Virginia in 1991 as a visiting senior scientist at Jefferson Lab. Since 1992, he has split his time as a full professor of physics at Old Dominion University in Norfolk, Virginia, and senior staff scientist at Jefferson Lab in Newport News, Virginia. Radyushkin is an author or co-author on 90 journal papers in his field, which have been referenced in more than 4,400 other publications. He is a member of the American Physical Society and was elected a Fellow of the Society in 1996.
Radyushkin and the six other Outstanding Scientists and Industrialists will be introduced to the Virginia Commonwealth General Assembly March 2. The honorees will receive their award medallions at a black-tie banquet at the Science Museum of Virginia March 30.