Steering of sub- GeV charged particle beams by use of reflections in thin crystal targets

The phenomenon of deflection of a charged particle beam due to channeling in a bent crystal has been well investigated and successfully applied for beam extraction at high-energy accelerators, for energies about 10 GeV and higher. However, it is of a big practical interest to consider the task of bending and extracting charged particles with energies below 1 GeV, for example, for production of ultrastable beams of low emittance for medical and biological applications. However, for low energy, i.e. below 1 GeV, the bent crystal channeling is not efficient. That motivates us to consider in this article an other crystal technique, based on thin straight crystal targets, as elements for the extraction and collimation of the circulating beam in an accelerator ring. The main advantages of reflection in straight crystals, in comparison with bent crystal channeling, consist in the small length of straight crystals along the beam, that reduces the amount of nuclear interactions and improves the background.