The vertical alignment of the DO overpass in the Fermilab Main Ring

The DO overpass was recently reconfigured in order to reduce the vertical dispersion in the Main Ring. The relationship between the global arrangement of the Main Ring quadrupoles and the placement of the quads in the overpass is described. There are various options that could have been adopted in dealing with the observed pattern: the pattern (and the closed orbit) could be kept the same while moving the quadrupoles several feet, the distribution could be smoothed, or the quads could be moved as though they had been on the global plane. The last option was chosen and an attempt to fix the closed orbit by moving quadrupoles outside the overpass was made. These corrections were applied using a modified version of DSCREWF; the surveyors were given elevation numbers which had already been corrected. The effect of these moves could be modeled using a conventional quadrupole move program.<>