  A series of Silicon crystal undulator samples were produced based on the
approach presented in PRL 90 (2003) 034801, with the periods of undulation from
0.1 mm to 1 mm, and the number of periods on the order of 10. The samples were
characterized by X-rays, revealing the sine-like shape of the crystal lattice
in the bulk. Next step in the characterization has been the channeling tests
done with 70 GeV protons, where good channeling properties of the undulated
Silicon lattice have been observed. The photon radiation tests of crystal
undulators with high energy positrons are in progress on several locations:
IHEP Protvino, LNF Frascati, and CERN SPS. The progress in the experimental
activities and the predictions from detailed simulations are reported.
