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 Physics at Virginia

Stefan Baeßler

Stefan Baeßler

Ph.D., 1996, University of Heidelberg
Professor

Experimental Nuclear and Particle Physics

sfb5d@virginia.edu
Office 169 JBL
243-1024

Research Interests

Professor Baeßler does research in fundamental symmetries, that is, precision tests of the Standard Model of Elementary Particles. His main activities are devoted to physics with cold neutrons at the SNS in Oak Ridge/Tennessee. He conducts experiments that study neutron beta decay (Nab and pNab). In addition, he is testing gravity with cold and ultracold neutrons at the ILL in Grenoble/France (GRANIT), and he is determining the magnetic moment of the muon (g-2) at Fermilab and tries to explain why it deviates from theory (MUonE) at CERN.

Selected Publications

  1. F.M. Gonzalez, J.H. Choi, H. Acharya, S. Clymer, A. Hagemeier, D.G. Mathews, A. Mendelsohn, A. Nelsen, H. Rahangdale, L. Richburg, R. Alarcon, A. Atencio, S. Baeßler et al., "First Full Dalitz Plot Measurement in Neutron -Decay using the Nab Spectrometer and Implications for New Physics", arXiv:2508.16045
  2. S. Baeßler, R. Alarcon, L. Barrón Palos, L.J. Broussard, J.H. Choi,  et al., “The pNab experiment and the quest for ever better neutron beam polarization”, Proceedings of Science (PSTP2024) 066
  3. M. Beck, W. Heil, C. Schmidt, S. Baeßler, F. Glück, G. Konrad, U. Schmidt, “Reanalysis of the electron antineutrino angular correlation measurement aSPECT with new constraints on Fierz interference”, Phys. Rev. Lett. 132, 102501 (2024)
  4. D.P. Aguillard, T. Albahri, D. Allspach, J. Annala, K. Badgley, S. Baeßler, et al., “Measurement of the Positive Muon Anomalous Magnetic Moment to 127 ppb”, Phys. Rev. Lett. 135, 101802 (2025), arXiv:2506.03069
  5. M.T. Gericke, S. Baeßler, L. Barrón-Palos, N. Birge, J.D. Bowman, J. Calarco, V. Cianciolo, C.E. Coppola, C.B. Crawford, N. Fomin, I. Garishvili, G. L. Greene, G.M. Hale, J. Hamblen, C. Hayes, E. Iverson, M.L. Kabir, M. McCrea, P. E. Mueller, S. Penttila, E. Plemons, A. Ramírez-Morales, E.M. Scott, J. Watts, C. Wickersham,“First Precision Measurement of the Parity Violating Asymmetry in Cold Neutron Capture on 3He”, Phys. Rev. Lett. 125, 131803 (2020)
  6. D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler et al.,“First Observation of P-odd γ Asymmetry in Polarized Neutron Capture on Hydrogen”, Phys. Rev. Lett. 121, 242002 (2018)

Complete list

News Items

The first result from the Muon g-2 experiment at Fermilab was unveiled and discussed publicly on Wednesday, 7 April 2021, in a special set of online seminars, that attracted widespread ......More >
The weak interaction of quarks between the neutron and proton have been measured for the first time by the NPDGamma experiment at the Spallation Neutron Source in Oak Ridge ......More >
Dinko Pocanic and Stefan Baessler, in collaboration with colleagues from Arizona State University and Oak Ridge National Lab, have received funding for the development of a spectrometer optimized ......More >

Departmental Committees

Beitchman Summer Graduate Research Fellowship Committee (Member)

Long Range Planning Committee (Member)

Graduate Student Admissions Committee (Member)

Committee on Teaching (Member)