A Magnetic Field Mapper to Improve Constraints on Exotic Spin-Dependent Interaction Searches

The Neutron Spin Rotation (NSR) collaboration employs slow neutron polarimetry to search for exotic spin-dependent interactions beyond the Standard Model. A previous experiment using a target composed of slotted copper and glass plates [1] set stringent bounds on the exotic axial coupling constant g_A² in the mesoscopic range [2]. Preparations are underway for a next-generation experiment using tungsten-glass and null (glass-glass) target configurations, with the goal of improving existing constraints by more than an order of magnitude. A dominant systematic uncertainty in this measurement arises from magnetic contamination in the target plates; to address this, the NSR group has developed a pT-sensitive 2-axis magnetic field mapping apparatus. We will present an overview of the magnetic field mapper, recent improvements to the hardware and software design, and preliminary field mapping results.

[1] C. Haddock et al., Nucl. Inst. Meth. A 885 (2018)

[2] C. Haddock et al., Phys. Lett. B 783 (2018)