Study of near-field vibration sources for the NLC linac components

The vibration stability requirements for the Next Linear Collider (NLC) are far more stringent than for the previous generation of colliders. To meet these goals, it is imperative that the effects of vibration on NLC linac components from near-field sources (e.g. compressors, high vacuum equipment, klystrons, modulators, pumps, fans, etc) be well understood. The civil construction method, whether cut-and-cover or parallel bored tunnels, can determine the proximity and possible isolation of noise sources. This paper presents a brief summary and analysis of recently completed and planned studies for characterization of near-field vibration sources under either construction method. The results of in-situ vibration measurements will also be included.