Multicrystal undulator

Radiation of positrons passing through a set of equidistant and mutually oriented crystals is considered. The thickness of each crystal is half of the particle trajectory period at planar channeling in a thick crystal. Passing through the set of half-wave crystals the particle moves on quasi-undulator trajectory. The radiation spectrum of such “multicrystal undulator”, consists of discrete harmonics, and the frequency of each harmonic and the number of harmonics in the spectrum depend on the spacing between the crystals, and on the particle energy. Varying the spacing between crystals one can tune the frequency of the first harmonic. A multicrystal undulator should be of particular assistance when there is a need to produce relatively soft radiation by use of a high energy particle beam.