Down in the LINAC tunnel, there are a total of 46 cryomodules in the beamline. Each one of these modules houses the cavities used to accelerate the beam. The cavities need to be supercooled to very low temperatures, so the cryomodules have cooling lines that use liquid helium to do so. The CA modules have 4 cavities each, CB have 8 each, CC have 6 each, and the CD have 8 each.