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The paper is devoted to the study of volume reflection and volume capture of high energy particles moving in planar fields of bent single crystals. The influence of volume capture on the process of volume reflection was considered analytically. Relations describing various distributions of particles involved in the process, the probability of volume capture and the behavior of channeling and dechanneling fractions of a beam were obtained. Results of the study will be useful in the realization of multicrystal devices for collimation and extraction of beams on modern and future accelerators.

In the experiment the efficiency of the 50 GeV proton beam extraction from accelerator by means of a bent crystal as a function of crystal orientation was measured. This allowed one to make a comparative analysis of efficiencies of high-energy protons deflection by different crystal atomic planes with different values of the electrostatic field. The results of simulation of high-energy protons deflection by means of crystal atomic planes and crystal atomic strings are also presented in the article. In the case of planar channeling the simulation shows a good agreement with experimental data. In the case of proton motion in the regime of stochastic scattering by bent atomic strings the simulation shows that angles of particle deflection are much greater than the critical channeling angle.

The process of photoproduction of electron-positron pairs in bent single crystals is considered. This consideration is based on the theory of coherent pairproduction in straight single crystals and take into account the linear polarization of the photon beam. In particular, it is shown that the probability of the process for γ quanta with energies from 100 GeV is significantly higher than the one in an amorphous medium. The positive features of the photoproduction in bent crystals compared to straight ones are underlined from the point of view of possible applications.

An analytical description of volume reflection of charged ultrarelativistic particles in bent single crystals is considered. The relation describing the angle of volume reflection as a function of the transversal energy is obtained. Different angle distributions of the scattered protons in single crystals are found. Results of calculations for 400 GeV protons scattered by the silicon single crystal are presented.

Crystalline undulators with periodically deformed crystallographic planes offer coherent electromagnetic fields on the order of 1000 T and provide undulator period L in submillimeter range. We present an idea for creation of a crystalline undulator and report its realization. One face of a silicon crystal was given periodic microscratches (grooves) by means of a diamond blade, with a period ranging from 0.1 to 0.5 mm in different samples. The x-ray tests of the crystal deformation have shown that a sinusoidal-like shape of crystalline planes goes through the bulk of the crystals. This opens up the possibility for experiments with high-energy particles channeled in the crystalline undulator, a new compact source of radiation. The first experiments on photon emission in the crystal undulator are in preparation at IHEP (Protvino) with 2–15 GeV positrons and at LNF (Frascati) with 500–800 MeV positrons, aiming to produce undulator photons in the range of 50–500 keV. The results of Monte Carlo simulations for the planned experiments are presented as well.