Linear Tuning and Estimates for the Initial Beam Based Alignment Requirements for the TESLA Beam Delivery System (BDS)

The Beam Delivery System (BDS) of the proposed TESLA linear collider contains some of the tightest magnet alignment tolerances of the entire machine. In [1], luminosity stability issues were covered in some detail, with specific emphasis on ground motion and magnet vibration. It was shown that ground motion effects and fast magnet vibration leads to relatively high values of both linear and second-order dispersion at the interaction point (IP). In this note, we estimate the related effects of the residual dispersion left after performing beam-based alignment of the magnets. Specifically, we want to estimate an RMS alignment goal which will need to be attained with beam-based techniques in order to achieve the required 5 nm vertical beam size at the IP.