High Pressure Gas Filled Cavities for use in Ionization Cooling Channels

A new technique for cooling beams of particles is ionization cooling. Ionization cooling consists of passing a beam through a material, thereby losing energy, followed by the beam passing through RF cavities to restore the lost longitudinal momentum. This inherently cools the beam in the transverse plane. If dispersion is introduced, emittance exchange allows six dimensional cooling to take place. One method by which to accomplish this involves using high pressure hydrogen gas filled RF cavities arranged in a helix within superconducting magnets. This so-called Helical Cooling Channel (HCC) provides ionization cooling through the pressurized cavities, and emittance exchange through solenoidal, helical dipole, and helical quadrupole magnetic fields. One caveat of the HCC is that normal conducting RF cavities must operate in strong magnetic fields. Recent results from the MuCool Test Area at Fermilab indicate that pressurized RF cavities will operate in such a channel. These results, along with other technology development, will be presented.