A continuously scanning separate-crystal single-photon x-ray interferometer

The feasibility of a new design and measurement concept of a combined optical and x-ray interferometer (COXI) is demonstrated here. Mechanical noise in the x-ray interferometer can be cancelled efficiently with fast and synchronous detection of the optical interferometer phase and x-ray counts. The scan-length requirement of the decadic step method of conventional COXI setups is reduced by more than one order of magnitude due to the correlation between single-photon interference events. The actual scan length of the shown setup is limited to 4 µm. It is estimated that a future update will enable us to measure the lattice parameter of 28Si, at least with the targeted relative statistical reproducibility of 3 × 10−9.