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In conventional beam based alignment (BBA) procedures, the relative alignmentof a quadrupole to a nearby beam position monitor is determined by finding abeam position in the quadrupole at which the closed orbit does not change whenthe quadrupole field is varied. The final focus magnets of the interactionregions (IR) of circular colliders often have some specialized properties thatmake it difficult to perform conventional beam based alignment procedures. Atthe HERA interaction points, for example, these properties are: (a) Thequadrupoles are quite strong and long. Therefore a thin lens approximation isquite imprecise. (b) The effects of angular magnet offsets become significant.(c) The possibilities to steer the beam are limited as long as the alignment isnot within specifications. (d) The beam orbit has design offsets and designangles with respect to the axis of the low-beta quadrupoles. (e) Oftenquadrupoles do not have a beam position monitor in their vicinity. Here wepresent a beam based alignment procedure that determines the relative offset ofthe closed orbit from a quadrupole center without requiring large orbit changesor monitors next to the quadrupole. Taking into account the alignment angleallows us to reduce the sensitivity to optical errors by one to two orders ofmagnitude. We also show how the BBA measurements of all IR quadrupoles can beused to determine the global position of the magnets. The sensitivity to errorsof this method is evaluated and its applicability to HERA is shown

Beam-based alignment of interaction region magnets