RUI: Precision Muon Physics

Regis University, Denver CO

Investigators

Abstract

This award will enable the Regis University nuclear physics group to make substantial contributions to two precision muon physics experiments over the next three years: the MuSun measurement of nuclear muon capture in deuterium at the Paul Scherrer Institute (PSI), and the Muon g-2 experiment at Fermilab. The MuSun collaboration will measure the rate of muon capture on the deuteron from the doublet spin state of the muonic deuterium atom to a precision of better than 1.5%. This will be the most precise determination to date, by an order of magnitude, of the rate for any two-nucleon weak-interaction process. The Regis group will develop low-power preamplifier circuits that will function in the cryogenic environment of this experiment, implement the response of the detector in the simulation software framework, and participate in the physics analysis. The Muon g-2 experiment will measure the anomalous magnetic moment of the muon to a precision of 0.15 parts per million (ppm), a substantial improvement from the 0.5 ppm that has been achieved in previous measurements. The current result disagrees with the prediction of the Standard Model by more than three standard deviations: enough to hint at the possibility of "new physics,'' but not yet enough to claim a discovery. This is one of a very small number of observables that cannot be understood in the context of the current Standard Model, and it provides an important constraint on extensions to it. The Regis group's initial responsibility will be to test, refurbish, and modernize the scintillating fiber beam monitors that are used to record the dynamic motion of the beam. The Muon g-2 experiment has the potential to uncover entirely new particles and interactions, perhaps even before they can be directly observed in experiments at the energy frontier. Similarly, the MuSun measurement will enable a precise characterization of proton-proton fusion, which is responsible for releasing energy in stars like our Sun, and also of the reactions that have been used by the Sudbury Neutrino Observatory to detect solar neutrinos. This science is at the forefront of subatomic physics, and a primary purpose of this award is to allow undergraduate students to become involved in it as research assistants. Regis University is a teaching-focused, primarily-undergraduate institution that is currently initiating formal majors in physics and computational physics as part of an ambitious expansion of its traditional liberal-arts programs. This award will complement the University's undergraduate research initiative, strengthening our students' education in mathematics, the sciences, and computing. Several students will be able to travel to PSI and Fermilab to participate in the construction and data collection for these experiments. Travel to collaboration meetings, for collaborative work with research university partners, and to academic conferences will also be supported.