The polarization of a neutron beam can be maintained over many meters by surrounding the beam with a uniform magnetic field.
A specialized magnet, similar to those produced for the Neutron Spin Rotation experiment, is required to maintain the polarization and re- orient the spins as the beam passes through the MSE walls and into the 30 milliGauss holding field.
–M. Maldonado-Velázquez, L. Barrón-Palos, C. Crawford, W.M. Snow, Nucl. Instrum. Meth. A854, 127 (2017). DOI: 10.1016/j.nima.2017.02.066
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