This work presents the improvements in the design and testing of polarimeters based on channel-cut crystals for nuclear resonant scattering experiments at the 14.4 keV resonance of 57Fe. By using four asymmetric reflections at asymmetry angles of α1 = -28°, α2 = 28°, α3 = -28° and α4 = 28°, the degree of polarization purity could be improved to 2.2 × 10-9. For users, an advanced polarimeter without beam offset is now available at beamline P01 of the storage ring PETRA III.
Keywords: X-ray polarimeter; asymmetric reflection; channel-cut crystal; nuclear resonant scattering.
open access.