Reinhard A. Schumacher Professor of Physics, Carnegie Mellon University Ph.D., Massachusetts Institute of Technology (1983) B.S., Case Western Reserve University (1978) Email: schumacher@cmu.edu Office: Wean Hall, Room 8406 Phone: 1-412-268-5177 Department of Physics Carnegie Mellon University Pittsburgh, PA 15213-3890

Quark interaction physics explores sub-atomic particle systems at the boundary between the quark-gluon and meson-baryon descriptions of matter. The field addresses questions that 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 Nuclear and Quark Interaction Physics.

My main area of research is in the electromagnetic production of strange particles (kaons and hyperons) and various baryon-antibaryon pairs. The production of strange-quark pairs via the well-known electromagnetic interaction is our avenue for refining understanding of baryon resonances, mesonic resonances, and associated polarization observables. Experimental results are compared with modern quark models and unitarized chiral perturbation theory with the use of partial wave analysis. We seek evidence for particle states that fall outside the traditional quark model classification scheme on account of active gluonic configurations.

This work is being done at the Thomas Jefferson National Accelerator Facility. My experimental work is done using the GlueX detector (GlueX) in Hall D at Jefferson Lab and (formerly) the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B.

Another research direction is using fMRI methods to study the encoding of scientific concept in the human brain, particularly those that do not have classical analogues. The neuroscience of advanced physics concepts in the brains of PhD Physicists versus young students can be compared, for example, to trace their cognitive foundations and development during learning.

At Carnegie Mellon I taught a number of different courses, and this comprised a very important part of my work before moving to emeritus faculty status. I taught Modern Essentials (33.211) (Relativity and Quantum Physics) in the fall and Modern Physics Laboratory (33.340) in the spring. I also produced some didactic YouTube videos on physics topics, such as A Diffusion Cloud Chamber and The Kelvin Water Dropper with Electroscope.

Selected Publications

• R. A. Mason, R. A. Schumacher, M. A. Just, The neuroscience of advanced scientific concepts , npj Science of Learning 6, 29 (2021).


• D. Ho, R. A. Schumacher, et al., Beam-target helicity asymmetry for γ n → π^- p in the N* resonance region (CLAS Collaboration), Physical Review Letters 118, 242002 (2017).


• R. Dickson, R. A. Schumacher, et al., Photoproduction of the f₁(1285) meson (CLAS Collaboration), Physical Review C 93, 065202 (2016).


• K. Moriya, R. A. Schumacher, et al., Spin and parity measurement of the Λ(1405) baryon (CLAS Collaboration), Physical Review Letters 112, 082004 (2014).


• K. Moriya, R. A. Schumacher, et al., Differential photoproduction cross sections of the Σ(1385), Λ(1405), and Λ(1520) (CLAS Collaboration), Physical Review C 88, 045201 (2013).


• K. Moriya, R. A. Schumacher, et al., Measurement of the Σπ photoproduction line shapes near the Λ(1405) (CLAS Collaboration), Physical Review C 87, 035206 (2013).


• G. Bernero, J. Olitsky, and R. A. Schumacher, Atmospheric dependence of the stopping cosmic ray muon rate at ground level, Journal of Physics G 40, 065203 (2013).


• R. A. Schumacher and M. M. Sargsian, Scaling and resonances in elementary K⁺Λ photoproduction, Physical Review C 83, 025207 (2011).


• R. A. Schumacher and B. Tarbet, A short Foucault pendulum free of ellipsoidal precession, arXiv:0902.1829 [physics.class-ph] (2009).


• R. Schumacher, Polarization in hyperon photo- and electro-production, The European Physical Journal A 35, 299 (2008).


• R. Bradford, R. A. Schumacher, et al., First measurement of beam-recoil observables C_x and C_z in hyperon photoproduction (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 γ+p→K⁺+Y for Λ and Σ⁰ hyperons (CLAS Collaboration), Physical Review C 73, 035202 (2006).


• R. A. Schumacher, The rise and fall of pentaquarks in experiments, AIP Conf. Proc. 842, 409 (2006).


• J. McNabb, R. A. Schumacher, L. Todor, et al., Hyperon photoproduction in the nucleon resonance region (CLAS Collaboration), Physical Review C 69, 042201 (2004).


• B.A. Mecking, et al., The CEBAF large acceptance spectrometer (CLAS) (CLAS Collaboration), Nuclear Instruments and Methods in Physics Research, Section A 503, 513 (2003).


• Stephan A. Roth and Reinhard A. Schumacher, A computer-controlled tension monitoring system for drift chamber wires, Nuclear Instruments and Methods in Physics Research Section A 369, 215 (1996).


• Reinhard A. Schumacher, Special relativity and the Michelson-Morley interferometer, American Journal of Physics 62, 609 (1994).


• Reinhard A. Schumacher, Possible violation of the ΔI = 1/2 Rule in non-mesonic hypernuclear weak decay, Nuclear Physics A 547, 143 (1992).


• R.A. Schumacher, P.A. Amaudruz, C.H.Q. Ingram, et al., Exclusive quasi-deuteron absorption of pions on ¹⁶O and ¹⁸O at 116 MeV, Phys.Rev. C38, 2205-2220 (1988).


• R.A. Schumacher, J.L. Matthews, W.W. Sapp, R.S. Turley, G.S. Adams, R.O. Owens, Two-body photodisintegration of ⁴He in the 100 MeV - 360 MeV region, Phys. Rev. C33, 50-58 (1986).


• R.A. Schumacher, G.S. Adams, D.R. Ingham, J.L. Matthews, W.W. Sapp, R.S. Turley, R.O. Owens, B.L. Roberts, Cu(γ, p)X reaction at Eγ = 150 MeV and 300 MeV, Phys.Rev. C25, 2269-2277 (1982).


• E. R. Kinney, J. L. Matthews, W.W. Sapp, R.A. Schumacher, R.O. Owens, A simple light guide for coupling to thin scintillator sheets, Nuclear Instruments and Methods 185, 189 (1981).

Click here for a longer publication list.

Selected Videos

• A Diffusion Cloud Chamber


• The Kelvin Water Dropper with Electroscope

Selected Talks

• Click here

Schumacher Group PhD Students

• John McNabb (2002)
• Robert Feuerbach (2002)
• Robert Bradford (2005)
• Kei Moriya (2010)
• Ryan Dickson (2011)
• Dao Ho (2015)
• Hao Li (2023)
• Dene Hoffman

Many students have been a part of the Carnegie Mellon Experimental Medium Energy Nuclear/Particle Group over the years

• Here is a list of all MEG Students

• The CMU Physics Department Information Page

Last modified: 2-24-2024 o