Physics

I am an experimental nuclear physicist with a joint position both as faculty at HU and as staff scientist at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) located not far from the HU campus. My research interests are to explore the internal structure of protons, neutrons and light nuclei with the help of electron scattering and by utilizing spin degrees of freedom, which I have pursued at several laboratories – the Mainz Microtron (MAMI) at University of Mainz, Germany, the S-DALINAC at the Technical University of Darmstadt, Germany, the MIT-Bates Linear Accelerator Center in Middleton, Massachusetts, and now at Jefferson Lab in Virginia. The electron scattering process is usually described in the framework of one-photon exchange, which allows using this method to explore strongly interacting matter such as nucleons and nuclei and their internal structure generated by quarks and gluons. The unprecedented precision of spin-dependent electron scattering has recently led to the question to what extent the exchange of two or more photons in the scattering process influences the observations. A definitive experiment to resolve this question (OLYMPUS) will be carried out in the near future at DESY in Hamburg, Germany, a large facility providing intense electron (and positron) beams. OLYMPUS is designed to very precisely compare elastic scattering of electrons with that of positrons in a storage ring from an internal proton target.

Another major research area of mine is the search for New Physics beyond the Standard Model. The observed excess of matter over antimatter in the universe cannot be explained with the current Standard Model, which on the other hand does account for all symmetry violations observed so far. According to A. Sakharov’s criteria, discovery of new sources of symmetry violations (such as charge-parity or time reversal) are required for our understanding of the cosmos. I have co-initiated the Time Reversal Experiment with Kaons (TREK) proposed at J-PARC in Japan, which aims to find such new sources in the decay of charged kaons produced at J-PARC.

For both experiments OLYMPUS and TREK, my group is constructing charged-particle tracking detectors based on Gas Electron Multiplier (GEM) technology, a novel technique originally developed at CERN in Switzerland. GEM-detectors are relatively inexpensive, less fragile than wire chambers, and can be run at very high particle rates in very harsh radiation environments.