Simulations of Neutron Spin Rotation Measurements by the NSR Collaboration*

The Neutron Spin Rotation (NSR) Collaboration seeks to constrain the hadronic weak interaction as well as place limits on the possibility of long-range spin-dependent forces [1,2,3]. The NSR polarimeter is capable of measuring rotations on the order of 10^-7 radians per meter of target material. As transversely polarized neutrons pass through a pair of 0.5-m liquid Helium targets, the weak interaction causes minute rotations of the neutron spin about the longitudinal axis. Similarly, transversely polarized neutrons can tip forward due to a spin-dependent long-range force as they pass between different-mass plates. For the latter experiment, 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.