Optimum strategy for energy degraders and ionization cooling

Methodology for calculating the profile and emittance of a particle beam as it is slowed down in matter, including the effects of multiple scattering, axial magnetic field and lithium lens. Strategies are determined for minimum final emittance. For ionization cooling, boron carbide has advantages over liquid hydrogen if the beam can be focused onto a small enough area, which may be possible using strong axial fields.