Fundamental Studies in Nuclear Physics

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The PI will make precise measurements of the physical properties of the neutron in three separate experiments. His main focus will be to develop a sensitive search for the electrical properties of the neutron by searching for an electric dipole moment (EDM). A neutron EDM could signal new physics beyond our current understanding of physics and help to explain why the universe is dominated by matter rather than equal amounts of matter and antimatter (as predicted by the present laws of physics). The asymmetry between matter and antimatter remains one of the great puzzles in our understanding of the evolution of the universe. The PI will also participate in the UCNtau (Ultra-Cold Neutron Lifetime) experiment where the goal is to trap neutrons to make a precise measurement of the lifetime of a free neutron. This provides important information about the weak nuclear force that is part of understanding the Big Bang at the beginning of the universe as well as nuclear energy generation in the sun. Participation in these experiments by postdoctoral scholars, graduate students, and undergraduates helps provide the nation with a highly trained workforce in Nuclear Science, with applications in medicine, technology, and national defense as well as basic science.The PI will use newly developed techniques to perform precision measurements with trapped Ultra-Cold Neutrons (UCN) at Los Alamos and Oak Ridge National Laboratory. His group has recently completed one of three independent analyses of the latest data from the UCNtau experiment which uses a magnetic/gravity neutron trap at the Los Alamos UCN facility. This data provides the world’s most precise measurement of the neutron lifetime, with a factor of two smaller uncertainty compared to previously published results. Future data taking will further improve the precision of the experiment. The team also plays a leading role in the development and construction of a new experiment which will be used to search for the Electric Dipole Moment (EDM) of the free neutron. The nEDM@SNS experiment (at the Spallation Neutron Source, ORNL) is designed to improve the sensitivity of the measurement by two orders-of-magnitude compared to previous experiments. The observation of a neutron EDM signals a violation of time-reversal symmetry and could provide important input related to the origin of the matter-antimatter asymmetry of the universe and new physical phenomena that may be responsible for it. The critical cryogenic magnets and magnetic shielding of the experiment will be commissioned and then installed and tested at the SNS using a cold-neutron beam to perform neutron polarization and transmission studies during the time frame of this grant.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.