High-energy channeling — applications in beam bending and extraction

When charged particles pass through a crystal along a crystallographic direction, the coherent scattering on the lattice atoms forces the particles to follow the lattice direction. The transmission through an aligned crystal is very different from the passage through an amorphous foil, and drastically changes the interaction with the crystal atoms. This channeling effect has many applications at low energy within both fundamental and applied physics. Also when the crystal is bent, the particles will follow the crystallographic direction. In this way, a crystal can deflect a high-energy beam corresponding to a magnetic field around 1000 T, although with some losses. The lecture will be biased towards high energies (> 1 GeV), and results from recent bending and extraction experiments at CERN will be presented.