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Multiple Bragg scattering is a source of phase information. A quantity δ called the triplet invariant can be determined: 
, where 
is the phase of the simultaneous reflection H, P is the main reflection, and P − H is the coupling reflection. Previous experiments on Al–Pd–Mn have always yielded δ values far from 0 or 180°, the only values compatible with a centrosymmetric structure. In this work, a new approach is used. Instead of concentrating on the wings of the azimuthal plots, the central region is considered where the H reflection is fully excited. Circularly polarized X-rays are also used. The difference in the azimuthal plots between left and right polarization is a source of phase information. This approach is feasible with Al–Pd–Mn because the crystal perfection of this material is outstanding and dynamical theory can be applied to all regions of the azimuthal plot. A noticeable difference in the azimuthal plots is visible when the helicity is switched. N-beam dynamical theory without approximations is used to fit theoretical profiles to the experimental azimuthal plots. In all cases, a triplet invariant δ = 50 
10° was found. It is confirmed that Al–Pd–Mn is not centrosymmetric.
, where 
is the phase of the simultaneous reflection H, P is the main reflection, and P − H is the coupling reflection. Previous experiments on Al–Pd–Mn have always yielded δ values far from 0 or 180°, the only values compatible with a centrosymmetric structure. In this work, a new approach is used. Instead of concentrating on the wings of the azimuthal plots, the central region is considered where the H reflection is fully excited. Circularly polarized X-rays are also used. The difference in the azimuthal plots between left and right polarization is a source of phase information. This approach is feasible with Al–Pd–Mn because the crystal perfection of this material is outstanding and dynamical theory can be applied to all regions of the azimuthal plot. A noticeable difference in the azimuthal plots is visible when the helicity is switched. N-beam dynamical theory without approximations is used to fit theoretical profiles to the experimental azimuthal plots. In all cases, a triplet invariant δ = 50 
10° was found. It is confirmed that Al–Pd–Mn is not centrosymmetric.
