Slow Neutron Polarimetry for a Spin-Dependent Fifth Force Search in Terbium Iron Garnet: Overview and Neutron Imaging Analysis

Polycrystalline rare-earth iron garnets are well-established ferrimagnetic materials exhibiting a non-zero net electron spin even at their compensation temperature. The NSR-Ferrimagnets Collaboration takes advantage of these polarized electron targets to search for exotic spin-dependent interactions between polarized electrons and polarized neutrons. By measuring polarized slow neutron spin rotation through a polarized electron target in different orientations at ORNL's HFIR CG-1D Multimodal Advanced Radiography Station (MARS), we characterize an asymmetry between spin states which places constraints on exotic fifth force candidates. This talk will discuss an overview of the novel neutron-electron spin interaction search conducted in June 2024 at MARS, including data acquisition and analysis techniques, neutron image corrections, statistical error budgeting, and detector characterization.