Optimization of a solid state polarizing bender for cold neutrons

We have designed a solid state bender to polarize cold neutrons for the Spin Echo Scattering Angle Measurement (SESAME) instrument at the Low Energy Neutron Source (LENS) at Indiana University. The design attempts to achieve high neutron polarization across a wide range of neutron wavelengths and divergence angles by optimizing the supermirror coating materials. The transmission and polarizing efficiency of the bender were modeled using the VITESS software, then measured at both continuous-wave and pulsed neutron sources. While the measured peak neutron transmission and polarization agree reasonably well with simulations, neither quantity has been successfully modeled for long wavelength neutrons. These results imply an insufficient understanding of the magnetic microstructure of the supermirror coatings used.