Professor of Physics, Applied Physics and Biomedical Engineering
University of Michigan
Randall Laboratory 450 Church Street
Ann Arbor, Michigan USA 48109
Tel: (1)-734-647-2514 Fax: (1)-734-764-5153
Physics 235 2013-2017
Go to Physics 126 Web Pages (Fall 2004)
Links to Public Lecture Videos on Sports, etc.
Professor Chupp and his group pursue a program that uses precision measurement techniques and symmetry principles in particle physics investigations and applies the technology developed for those investigations to a variety of endeavors. The primary current efforts include measurement of muon magnetic-moment anomaly (g-2) at FERMILAB, fundamental neutron physics and atomic and neutron electric-dipole-moment measurements.
Over recent decades experiment and theory have established the Standard Model of elementary particle interactions and developed a framework for precise calculations. In spite of this success, strong evidence that the Standard Model is incomplete is provided by three specific shortcomings: 1) we do not understand the origin of matter, that is how the early universe evolved to provide more matter than antimatter for planets, stars and galaxies to exist as observed today; 2) we do not know what constitutes the dark matter that comprises most of the mass of the observable universe; 3) we have not specified the quantum mechanics of neutrinos, the elusive elementary particles that accompany radioactive decay. It is clear that a New Standard Model must emerge and that it must be based on experiment. The research presented in this proposal challenges precise Standard Model predictions and can provide solid signals of new physics by 1) measuring the magnetic signature (magnetic-moment anomaly) of the muon, an exotic elementary particle that is produced in abundance at the Fermi National Accelerator Laboratory and 2) studying the detailed behavior of radioactive neutrons as they decay. This work addresses the deepest questions that we can ask: what is matter made of, how did it come to be and how does it interact at the same time addressing the technical demands of the experiments by pushing the limits of magnetic field measurement. Many potential additional applications of these techniques may be extended into biology, neuroscience and medicine.
The measured g-2 of the muon differs from the Standard Model prediction by 3.6-σ and is currently the strongest laboratory signal for new physics. The absolute and accurate measurement of the magnetic field at the 70 ppb (parts-per-billion) level is required to reduce the uncertainty by a factor of four, which would strengthen the signal to 7-s and a bona-fide discovery if the central value does not change.
Neutron beta-decay provides a unique window into new physics, and we are contributing to a new generation of high precision experiments including the rare radiative decay mode of the neutron, the possibility of an improved cold-beam neutron lifetime measurement and Nab, measurement of the beta-neutrino asymmetry using a magnetic proton-time-of-flight spectrometer.
Time reversal invariance violation is also manifest in the permanent electric dipole moments (EDMs) induced in the neutron and atoms by elementary particle interactions beyond the Standard Model that may hold the key to the origin of matter. Rare isotopes, e.g. 223-Rn, are used because large enhancements of time-reversal violating effects are expected due to octupole deformation of the nucleus. Experiment S-929 at TRIUMF will measure the EDM of 223-Rn. The Facility for Rare Isotope Beam, FRIB, at Michigan State University can produce much greater quantities of 223-Rn and provide for more precise measurements. The HeXe collaboration aims significantly improve our earlier work to measure the 129Xe EDM using 3He comagnetometry using SQUID magnetometers and the world’s best magnetically shielded environments in Munich and Berlin, Germany.
Efforts to exploit the world’s strongest UCN sources at Los Alamos and ILL in Grenoble France are driving our work to push the neutron EDM sensitivity an order of magnitude and more.
Our group continues to work on applications of laser polarized 129Xe and 3He.