Advanced X-ray polarimeter design for nuclear resonant scattering

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 (57)Fe. By using four asymmetric reflections at asymmetry angles of α(1) = −28°, α(2) = 28°, α(3) = −28° and α(4) = 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.