A SIX-DIMENSIONAL MUON BEAM COOLING EXPERIMENT *

cooling, a method for shrinking the size of a particle beam, is an essential technique for the use of muons in future particle accelerators. Muon colliders and neutrino factories, examples of such future accelerators, depend on the development of robust and affordable ionization cooling technologies. A 6D cooling experiment has been proposed, incorporating a novel configuration of helical and solenoidal magnets in a prototype cooling channel. This Helical Cooling Channel (HCC) experiment is being designed to provide an affordable and striking demonstration that 6D muon beam cooling is understood well enough to enable intense neutrino factories and high-luminosity muon colliders. Because of the large amount of expected beam cooling, helium instead of hydrogen can be used for the initial experiment, avoiding the safety complications of hydrogen. The main points of the experiment are described and corresponding numerical simulations are reviewed.