Measuring scattering angles with neutron spin echo

We report results of experiments designed to test the use of thin magnetic films as elements of a neutron spin echo (NSE) apparatus for determining neutron scattering angles. We show that 10-μm thin films of Permalloy (Ni0.8 Fe0.2) electrodeposited on silicon wafers function well as π/2 spin rotators. 30 μm thick films of the same material used as precession fields in the NSE set-up allow the neutron scattering angle to be determined with a resolution of about 0.05°. We show that, even when the NSE angular resolution is comparable to the angular divergence of neutron beams used in a reflectometry experiment, the use of NSE aids in the separation of specular and diffuse scattering.