Fundamental Neutron Physics at NIST

The program in fundamental neutron~physics at the National Institute of Standards and Technology (NIST) began nearly two decades ago. Currently, five neutron beam lines are dedicated~to studies of fundamental neutron interactions. The neutrons are provided by the NIST Center for Neutron Research (NCNR), a national user facility for studies that include condensed matter physics, materials science, nuclear chemistry, and biological science. The beam lines for fundamental neutron physics experiments include a high intensity polychromatic beam, three monochromatic beams (0.496 nm,~0.89 nm, and .384 nm), and a neutron interferometer and optics facility (0.2 nm -- 0.49 nm). The presentation will discuss the broad program in fundamental neutron physics with a brief description of some of the experiments performed at the NCNR. In addition, the status of the new guide expansion project that includes a new neutron guide that will provide an additional very high intensity polychromatic beam for fundamental physics research will be presented.