Luminosity Stability Issues for the TESLA Beam Delivery System (BDS)

Given the extremely small beam sizes required at the interaction point (IP) of the next generation of linear colliders, it has long been understood that particular attention must be made to component stability, in particularly with respect to ground motion and vibration. The beam deliver systems (BDS) contain some of the most tightest alignment tolerances of the entire machine. There have been many studies of the effects of ground motion and vibration in linear colliders both for TESLA and NLC/JLC (see for example [1,2]), and a recent review of stability issues for beam delivery systems can be found in [3]. In the TESLA conceptual design report (CDR) [4], studies of luminosity stability were made based on the so-called ATL ground motion model [5]. Since publication of the CDR, the TESLA BDS has undergone several major modifications: