Charged Particles In Bent Crystal Research Articles

Energy dependence of the efficiency of high-energy negatively charged particle beam deflection by planar channeling in a bent crystal

The study of planar channeling of high-energy negatively charged particles in bent crystals was carried out. The value of the critical radius of planar channeling in the Doyle–Turner approximation for the atomic potential is determined. The dependence of the maximum angle at which a given fraction of beam particles could be deflected by means of planar channeling in a bent crystal on the particle energy was found. We identified the ideal parameters for the exploitation of planar channeling for negatively charged particle beam deflection by planar channeling in a bent crystal at current and future high-energy accelerators, e.g., SLAC, MAMI, ILC or muon colliders.

Radiation generated by single and multiple volume reflection of ultrarelativistic electrons and positrons in bent crystals

Recently discovered processes of volume reflection and multiple volume reflection of charged particles in bent crystals are accompanied by specific electromagnetic (e.m.) radiation. The mechanism of radiation emission is quite complex due to the coexistence of different regimes for particle dynamics, resulting in e.m. generation with features characteristic of each regime. We present a simulation taking into consideration both the nondipole nature and arbitrary multiplicity of radiation accompanying volume reflection. This approach is worked out for electrons or positrons of any energy and is based on the local straight-crystal approximation and Baier-Katkov formula for radiation, the integration of which is considerably facilitated by the fast Fourier transform method. The radiation generated by multiple volume reflection with vertical and skew planes has been studied, too. A large axial contribution to the hard part of the radiative energy loss spectrum as well as the strengthening of planar radiation, with respect to the single volume reflection case, in the soft part of the spectrum are demonstrated. Both the wide spectrum and high intensity make this type of radiation quite suitable for the conversion of electron and positron beams to hard $\ensuremath{\gamma}$ radiation.

Particle channeling in a bent crystal

The channeling of high-energy charged particles in bent crystals is being used more and more extensively for steering particle beams at accelerators, for extracting a beam or its halo from an accelerator, and for splitting the extracted beam. The use of the strong intracrystalline fields of bent crystals in high-energy physics, for example, to measure the magnetic moments of short-lived particles from the spin precession angle in a bent crystal, appears to be very promising. The results of studies on the channeling of high-energy particles in a bent crystal are reviewed. The features of channeling and quasichanneling, the ionization energy losses, and the radiation emitted by channeled particles are studied. The possibility of polarization effects for channeled particles is discussed.

“Volume reflection” of high-energy charged particles in quasi-channeling states in bent crystals

Planar quasi-channeling of high-energy charged particles in bent crystal is considered. In the computer analysis of particle trajectories it is discovered that at a crystal bend far from the critical one quasi-channeled particles are deflected to the side opposite to the bend, i.e. a “volume reflection” of particles (positive and negative) by the field of bent atomic planes takes place.