Magnetised foils as ?-flippers in spin-echo spectrometry

The use of π-flippers for correction of line integrals in Larmor-precession devices is described. The π-flippersconsist of magnetised foils of the proper thickness, magnetised by the field of the precession device itself. Application of such π-flippers in a spin-echo small angle neutron scattering set-up with fields perpendicular and parallel to the beam direction is discussed. It appears that such flippers avoid corrections for the inhomogeneity of the field-line integrals, for the main part, in both options.