Neutron spin turners with a rotating magnetic field: first experiments

Spin turners are the key elements of a neutron spin-echo spectrometer with rotating magnetic fields. Here we describe the results of experiments with thin-film spin turners made of 25 µm amorphous ferromagnetic foils, whose in-plane magnetization is rotated by a weak external rotating field. The behaviour of the polarization vector of a 0.2 nm neutron beam is analysed in 3D after transmission through such a foil and, apart from a non-negligible depolarization, the results show that they are in good accordance with simulations. This observed depolarization is due to a domain structure with a net magnetization.