Design and commissioning of the D0 vertical nondispersive overpass in the Fermilab Main Ring

A vertical overpass in the Fermilab Main Ring around a future D0 proton-antiproton collision detector was designed and built to raise the initial luminosity for collider physics. The overpass provides a better dispersion match between the Main Ring and the Tevatron, and in the Main Ring substantially lowers the vertical beam size arising from momentum spread. This has also improved the overall efficiency and beam intensity of the Main Ring. Vertical dispersion was measured before and after completing the overpass. A high degree of correspondence was obtained between the predicted and measured values of vertical dispersion around the whole Main Ring. The Main Ring performance improved considerably with respect to beam intensity (which was raised from 1.2×10¹² to 1.8×10¹² protons per batch) as well as with respect to the Main Ring overall efficiency (which was raised from 85% up to 93%)