Experimental calibration of VUV ring optics

The individual quadrupole gradients, undulator focusing, beam position monitor (BPM) gains, and orbit steering magnet calibrations in the NSLS VUV Ring were determined by analyzing the measured orbit response matrix with the computer code LOCO (Linear Optics from Closed Orbits). The measured orbit response matrix is the change in orbit at the BPMs with changes in steering magnet excitation. The analysis showed beta function distortions of ±35% and ±25% horizontally and vertically. The design periodicity of the optics was restored by adjusting the quadrupole gradients to restore the periodicity of the response matrix. This lead to an increase of about 18 percent in the beam lifetime at 500 mA with a slight (3 and 7 percent) decrease in both the horizontal and vertical electron emittances as determined from the beam sizes measured using a synchrotron light monitor