Design considerations for beam tube penetration of a liquid argon collider detector

At the D-Zero collider detector, the Tevatron beam must pass through the massive end iron and liquid-argon end calorimeter in order for proton/anti-proton collisions to occur within the central tracking chamber. The authors discuss the brazed beryllium (low atomic mass) beam tube through central tracking and the necessary magnetic shielding of the beam tube through the end calorimeter cryostat and end iron. Vacuum system issues, including custom ion pumps, low-profile all-metal valves, reduction of outgassing within the beam tube, and anticipated pressure distribution, are presented. The requirement of access to the central tracking by rolling back the liquid-argon-filled end calorimeter cryostat is addressed with flexible bellows, integral heaters, and force sensors to protect the beam tube. Installation, collider roll-in, and interface to low-beta quadrupole magnet details are also presented. Implications for SSC (Superconducting Super Collider) configuration within the collider facilities are evident.<>