Low Energy, High Precision Muon Experiments

Intellectual merit We propose continuing research involving low energy, high precision muon experiments at Paul Scherrer Institute (PSI) and Fermilab. The experiments will yield enduring determinations of the A = 2 weak nuclear interaction and the muon anomalous magnetic moment. Both projects were highlighted in the 2007 Long Range Plan for Nuclear Science and nicely dovetail with other U.S. efforts at the Intensity Frontier. In the ongoing MuSun experiment at PSI we will measure the ƒÊ.d �¨ nnƒË doublet capture rate to �}1.5%. This A = 2 process is closely related to important weak nuclear processes in astrophysics (e.g. pp fusion) and neutrino physics (e.g. ƒËd interactions) but available data on ƒÊ.d capture are imprecise and inconsistent. The ƒÊ.d �¨ nnƒË process is the ideal probe of the elusive two-body weak axial current that influences processes from stellar evolution to neutrinoless double beta decay. A precision measurement of ƒÊ.d capture is particularly timely given recent advances in effective field theory applications to few-body weak nuclear processes. In the new g-2 experiment at Fermilab we will measure the muon anomalous magnetic moment aƒÊ to �}0.14 ppm; a four-fold improvement over BNL Expt. 821. The measurement will render both an exacting test of the standard model and a sensitive search for the physics beyond. The measurement will addresses the longstanding discrepancy between the Standard Model calculation and the BNL E821 result for the anomaly aƒÊ. It also complements the physics reach of the Large Hadron Collider. The PI�fs group is playing a major role in the two projects. In the MuSun experiment we are responsible for the neutron detector array and the data acquisition system and in the g-2 experiment we are responsible for the development of the data acquisition system. The PI is coleader of the detector team in the g-2 experiment and our post-doc is project leader for the data acquisition in the MuSun experiment. Two Kentucky PhD students are involved in MuSun; Ms. Nandita Raha who will complete her dissertation from the 2011 MuSun production run and Mr. Kres Neely who will complete his dissertation from the 2013-14 MuSun production runs. Several Kentucky physics majors have worked on R&D for g-2 and additional physics majors and computer engineering/science students will be working on the project in the future. The MuSun experiment began its production running in 2011 and will continue running through 2014. The g-2 experiment received stage one approval at Fermilab in Jan. 2011. The dis-assembly, relocation and re-assembly of the muon storage ring on the Fermilab site is planned for 2013-2014, with prototyping of detector systems during 2012-13, installation of detector systems in 2015, and data taking in 2016-17. Broader impact The proposed research activities includes substantial broader impact. The PI will continue his efforts to engage high school students, physics majors, computer engineering/science students and physics graduate students in his research activities. The PI will continue his efforts to advance our department�fs graduate program as Director of Graduate Studies. The PI will continue his work on general education reform and online course materials through his teaching of general physics classes. The PI will also continue his outreach activities at the local St. Peter and Paul Elementary and Middle School. Additionally, our research activities in high-speed acquisition and high-volume analysis will expose our students to cutting-edge aspects of modern computing. Our research theme of precision measurements of fundamental properties and elementary interactions involves determinations of textbook quantities with broad interest across nuclear, particle and astrophysics.