This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The research projects covers several research projects in which very low energy neutrons are used to strengthen our understanding of fundamental interactions. In the first project, several observables in neutron beta decay are studied; the combination of these observables with another experimental result (the determination of the neutron lifetime) determines the coupling constants of the weak interaction which causes the neutron decay. They are used as a sensitive test of the validity of the present theory which describes weak interaction coupling nucleons to leptons (the electrons and neutrinos produced in neutron decay). A related process is the weak coupling between nucleons and other nucleons, and the second project, a measurement of the asymmetry in the direction of gamma ray emission relative to the polarization of a neutron in the neutron capture on protons, is performed to determine the strength the dominant process of the weak interaction between nucleons. The third project is the characterization of gravitationally bound quantum states of ultracold neutron in the gravitational field over a glass mirror. A series of experiments is used to search for new short range interactions which would influence these quantum states. Finally, a purifier will be built for Helium-4 which is used as a production target for ultracold neutrons in a search for the electric dipole moment of the neutron. The Helium-3 contamination has to be reduced far below the natural abundance to avoid the reassertion of the ultracold neutrons on Helium-3 impurities.
The common goal of this experimental program is to test the Standard Model in regions which were not accessible before, or at least not as precise. A discovery of something not explained in the Standard Model would have important implications for High Energy Physics and Cosmology. Additional, the experiments have a high educational potential: Besides the advantages of working on scientifically visible and technologically challenging projects, the work ethics taught in medium-size collaborations of US and international institutions is of great value to students, be it as future scientist or outside academia.
