The vacuum system must achieve sufficiently low pressures for acceptable beam lifetime and low CLEO background rates. It must be compatible with masks to control synchrotron radiation and shield against particle background. The inner surface should have sufficient conductivity and smoothness to minimize resistive and higher order mode RF losses. Adequate cooling must be provided to remove the heat deposited by electro-magnetic and synchrotron radiation processes. The chamber radius must be large enough to accommodate the full beam-stay-clear requirements. The central chamber should present a minimum of scattering material to the decay products from the interaction point.
The vacuum system is similar in concept to that planned for Phase 2 upgrade operation. The double-walled beryllium central pipe will handle the heat load expected in Phase 3 operation. The pipe in the permanent magnet and superconducting quads will be double walled with coolant circulating between the inner and outer skins. Pumping would be provided by a titanium sublimation or NEG pump located just beyond the superconducting quad.
Beam diagnostic instrumentation will be installed as part of the vacuum system (e.g., beam position monitors, luminosity monitors, beam loss detectors). These are not considered in detail in this study.