  We present an idea for creation of a crystalline undulator and report its
first realization. One face of a silicon crystal was given periodic
micro-scratches (trenches) by means of a diamond blade. The X-ray tests of the
crystal deformation due to given periodic pattern of surface scratches have
shown that a sinusoidal shape is observed on both the scratched surface and the
opposite (unscratched) face of the crystal, that is, a periodic sinusoidal
deformation goes through the bulk of the crystal. This opens up the possibility
for experiments with high-energy particles channeled in crystalline undulator,
a novel compact source of radiation.
