Rf Cavity Vacuum Interlock System

conductivity. Production of cryomodules, the fundamental building block of the machine, has started. A cryomodule consists of four sets of pairs of 1497 MHs, 5 cell niobium cavi- ties contained in separate helium vessels and mounted in a cryostat with ap,propriate end caps for helium supply and return. Beam vacuum of the cavities, the connecting beam piping, the waveguides, and the cryostat insulating vacuum are crucial to the performance of the machine. The design and initial experience of the vacuum systems for the first 2 l/4 cryomodules that makeup the 45 MEV injector will be discussed.