Fig. 1
Experimental setup and principle of polarized neutron grating interferometry (pnGI). a Sketch of the pnGI setup for polarized neutrons. The setup consists of an adiabatic fast passage spin flipper (AFP), a beryllium filter (Be filter), a source grating G0, a phase grating G1, an analyzer grating G2, a detector, and a guide field system. The magnetic sample is placed between G0 and G1, the North and the South poles are depicted in red and blue, respectively. The parameter ω is the rotation angle of the gratings and the sample around the x-axis, the configuration in the sketch corresponds to ω = 0°, and dt1 is the Talbot distance. b Phase shift, ΔΦ, of the neutron wavefront induced by the magnetic interaction with a phase object, refracted by an angle α. c Schematic top view of a pnGI setup depicting the perturbations of the incident neutron wavefront, induced by refraction on a phase object in the beam, which lead to local displacement of the interference pattern. The intensity modulation is detected by each (i, j)-pixel on the matrix detector. The phase-stepping approach is adopted by scanning one grating along the transverse direction, yg. Further information about phase-stepping method for pnGI and contrast mechanism can be found in the Supplementary Note 1
