Linac Coherent Light Source
More Magnetic Milestones in the MMF

The first LCLS undulator to be mounted to its girder, undergoing coordinate measurement
by Brad Plummer
Last week, undulator work in SLAC's Magnetic Measurement Facility (MMF) for the Linac Coherent Light Source (LCLS) entered a new chapter as workers for the first time mated an undulator with the girder to which it will eventually be mounted in the Undulator Hall (UH). This marks a further step toward the beginning of installation, scheduled to begin in the next few months as work on the UH nears completion.

As one would expect of a machine as complex as the LCLS, pairing an undulator and girder is a bit more complicated that simply tightening a few bolts. Each undulator weighs 1,800 pounds, and the girders weigh 2,600 pounds—but despite that degree of heft, the interface between the two must be precise down to 20 microns, or one-fifth the width of a human hair. Verifying the precision machining of the girders, which will be mounted permanently to their stands in the UH, is critical to ensuring the undulators may be swapped as needed without having to dismantle the beam pipe. The beam pipe itself will also be secured to the undulator girders.

"We're working very hard to certify the undulators conform to the optimal design specifications, and this is one more step toward completing that job," said Metrology Department team leader Eric Lundahl. "It's exciting to see the LCLS moving forward."
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