My Research Program
My experimental research program is centered on the boundary between nuclear and elementary particle physics. The last 30 years have brought ample evidence that the building blocks of the nucleus - protons and neutrons - are made up from point-like particles called quarks. While the basic properties and interactions of quarks are well understood, it is still an open question how quarks make up a nucleon (a proton or neutron) - what the quark wave function of a nucleon is - and how the quark substructure of nucleons influences (and is influenced by) the forces that bind them into nuclei.

For instance, there has been a vivid debate on whether one can understand the intrinsic angular momentum - the spin - of a nucleon as a sum of the spins of the quarks which are inside it. Several experiments have investigated this question in the past by scattering polarized (spin-oriented) high-energy electrons and muons from polarized nucleon targets. I have been actively involved in a large program of experiments at the Stanford Linear Accelerator Center (SLAC, in California). Five of these experiments have been completed and their data published. At the same time, I am leading a complementary program (the EG1 run group) at lower energies, at the Thomas Jefferson National Accelerator Facility (JLab) in nearby Newport News. The combined information of these experiments allows us to understand the transition from the small-distance structure of nucleons (quasi-free quarks) to its static properties (magnetic moment and spin).

Another part of my research program uses the unique facilities of JLab (continuous electron beam combined with the large acceptance spectrometer CLAS) to study the differences of the quark structure of bound and free nucleons. As part of this program, I am leading an experiment (called "BoNuS") that measures, for the first time, the unpolarized structure function for a (nearly) free neutron, undistorted by nuclear binding effects. At the same time, an experiment (E6) that has already been concluded can give us information on how this free neutron structure becomes distorted if the neutron gets very close to another nucleon.

I am part of the Experimental Nuclear Physics group at ODU that has built six large detector components (drift chambers) for the CLAS in preparation for these and other experiments. The research of the Experimental Nuclear Physics Group at ODU is being sponsored by the U.S. Department of Energy and typically involves 6 faculty, 2 postdoctoral research associates, a dozen graduate students and several undergraduate students.

Here is a recent writeup in the "Courier" explaining my research "for the interested layperson".
For my lecture "The Structure of the Neutron" on September 28th, 2004, click here.
And here is a recent presentation to ODU graduate students.

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