Medium energy physics explores the interactions of few- and many-particle systems at the interface between the quark-gluon and meson-baryon descriptions of matter. Medium energy physics tends to address questions that, as a practical matter, do not require the highest beam energies or luminosities, but do call for high-precision measurements using specialized equipment. At Carnegie Mellon we have a large research group doing Medium Energy Physics. 

Currently, my main area of work is in the electromagnetic production of strange particles (kaons and hyperons).  The production of strange-quark pairs via the well-known electromagnetic interaction (via photon and electron-induced reactions) gives us an avenue for refining our knowledge of baryon resonances and coupling constants; the results are compared with modern quark model calculations. This work is being done at the Thomas Jefferson National Accelerator Facility . More exactly, my work is done using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at Jefferson Lab. 

At Carnegie Mellon I teach a number of different courses, and this comprises a very important part of my work.  

Selected Publications

R. Bradford, R. A. Schumacher, et al., "First Measurement of Beam-Recoil Observables Cx and Cz in Hyperon Photoproduction." (The CLAS Collaboration) Physical Review C 75, 035205 (2007).

R. Bradford, R. A. Schumacher, J.W.C. McNabb, L. Todor et al., "Differential Cross Sections for gamma + p --> K+ Y for Lambda and Sigma^0 Hyperons." (The CLAS Collaboration) Physical Review C 73, 035202 (2006).

R. A. Schumacher "The Rise and Fall of Pentaquarks in Experiments." Proceedings of PANIC 2005; arXiv:nucl-ex/0512019.

J.W.C. McNabb, R. A. Schumacher, L. Todor et al., "Hyperon Photoproduction in the Nucleon Resonance Region." (The CLAS Collaboration) Physical Review C 69, 042201 (2004).

Reinhard A. Schumacher, "Strangeness Production and Other Recent Results from Hall B at Jefferson Lab." European Physics Journal A 18, 371-375 (2003).

B. Mecking et al., "The CEBAF Large Acceptance Spectrometer (CLAS)." Nuclear Instruments and Methods in Physics Research (NIM) A 503, 513 (2003).

F. Merrill et al, "H-dibaryon Search via Xi- Capture on the Deuteron." Physical Review C 63 035206 (2001).

Schumacher, R.A., "Photoproduction Evidence For and Against Hidden-Strangeness States Near 2 GeV", Physical Review C 56, 2774 (1997).

Roth, S.A. and R.A. Schumacher, "A Computer-Controlled Tension Monitoring System For Drift Chamber Wires", Nuclear Instruments and Methods, A 369, 215 (1996).

Reinhard A. Schumacher, "Special Relativity and the Michelson-Morley Interferometer." American Journal of Physics 62: 609 (1994).