Simulations of a Search for Exotic Forces via Neutron Spin Rotation

In addtion to efforts to improve measurements of parity violation in the n-⁴He system, the Neutron Spin Rotation (NSR) Collaboration seeks to place limits on the possibility of exotic long-range spin-dependent forces [1,2]. The NSR polarimeter is capable of measuring rotations on the order of 10^-7 rad per meter of target material [3]. Transversely polarized neutrons can tip forward due to a spin-dependent long-range force as neutrons pass between different-mass plates. Our target consists of a series of 0.5-m long glass and tungsten plates and can accept a 10-by-10 cm beam. The primary challenge of these high-precision measurements is the suppression of and cancellation of rotations due to the interaction of the neutron spin with ambient magnetic fields. Computer simulations of these experiments have proved a valuable tool in investigating the size of these affects and how to mitigate them. Discussion of recent simulation work will be presented.