Magnetic field stepper between opposite precession devices in neutron spin-echo instruments

The transition region along a neutron beam between two opposite fields, perpendicular to that beam and characterised by a field gradient along that beam, causes depolarisation of the beam. By introducing a field jump at the zero point, this depolarisation can be reduced. Here, we analyse this field jump together with the effects of field gradients on the behaviour of neutron polarisation by passing that transition. It appears that by using a field jump created by a current sheet of finite height, the effects of the transition region on the neutron polarisation can be suppressed severely.