A Search for Exotic Spin-Gravity Couplings Through Polarized Neutron Interferometry*

In 1975 Collela, Overhauser, and Werner demonstrated the accessibility of gravitationally- induced phase shifts in quantum systems using perfect silicon crystal neutron interferometry. [1] Recently, further measurement of this effect has been made using the OffSpec instrument (ISIS-RAL) in spin-echo mode to act as a polarized neutron interferometer. [2] The ability to interfere neutrons of various polarization orientations to measure gravitationally-induced phase shifts provides an opportunity to search for spin-dependent gravitational effects. [3] I will describe a direct search for Lorentz violating spin-gravity couplings in the fermion sector of the Standard Model Extension. [4] An overview of the experimental system will be presented, as well as the status of data collection and analysis.\\ \\$[1]$ R. Colella, A.W. Overhauser, S.A. Werner, Phys. Rev. Lett. 34 (1975)\\ $[2]$ V.O. de Haan, {\it et al.}, Phys. Rev. A 89 (2014)\\ $[3]$ Y. Bonder, Phys. Rev. D 88 (2013)\\ $[4]$ Z. Li and A. Kostelecky, private communication (2019)