Novel Interferometer in the Soft X-Ray Region

S. Dambach, H. Backe, Th. Doerk, N. Eftekhari, H. Euteneuer, F. Görgen, F. Hagenbuck, K. H. Kaiser, O. Kettig, G. Kube, W. Lauth, H. Schöpe (+3 others)
1998 Physical Review Letters  
A novel interferometer has been developed with which the complex index of refraction of thin self-supporting foils can be measured in the vacuum ultraviolet and soft x-ray region. It consists of two collinear undulators and a grating spectrometer. Taking advantage of the low emittance 855 MeV electron beam from the Mainz Microtron, distinct intensity oscillations have been observed as a function of the distance between the undulators. A foil placed between the undulators causes a phase shift
more » ... an attenuation of the oscillation amplitude. The complex index of refraction has been measured at the K-absorption edge of carbon. [S0031-9007(98)
doi:10.1103/physrevlett.80.5473 fatcat:g4ovkzf5efglxbmpbglm5avpvm