Re-Visiting SPEAR After 25 Years (Presentation material)

Abstract

The SPEAR machine was completed in 1972. It consists of a single ring about 80 meters in diameter and started its very productive life as a positron-electron collider circulating beams up to 4 GeV. Synchrotron radiation research began almost immediately parasitically, then as half the program in the 1980s, and then became the whole program in 1991. The original network surveys used optical theodolites and invar tapes to place ring monuments in their ideal positions at constant offsets from the lines of ring quadrupoles. Optical tooling techniques were used to reference the monuments and survey offset targets on fixtures attached to the magnets. For more than 20 years neither the monuments nor magnets were restored to their ideal positions; the obvious discrepancies were simply ''feathered''. In 1992 SLC technology was used for the first time to re-measure the network and map the magnets. The discovery of many multiple-millimeter problems spurred planning for a 1995 global re-alignment. In 1995, all storage ring magnets and beamlines were mapped and moved. The band of displacements from ideal was reduced from about +/- 5mm to +/- 0.5mm. Upon start-up, beam stored without correctors