Final Days for Final Focus Test Beam
Image: A bird’s eye view of the Research Yard shows the Final Focus Test Beam (shaded), which will be removed to make way for the Beam Transport Hall (dashed lines) of the Linac Coherent Light Source.
The Final Focus Test Beam enters its final days this winter. Starting April 10, SLAC will turn off beam to the facility and begin its removal to make way for construction of the Beam Transport Hall for the Linac Coherent Light Source.
The 200-meter beamline runs from the Beam Switch Yard at the end of the two-mile linac out into the Research Yard. About 100 meters of the beamline are underground, and the remainder is visible as a long concrete building in the Research Yard.
The FFTB was originally built to demonstrate technology for focusing and measuring sub-micron electron beams suitable for a future linear collider. Thanks to its small beam emittance and ultra-short electron bunches, it became a microcosm of SLAC, hosting experiments in astrophysics, photon science and cutting-edge accelerator research. Experimenters are currently logging as much beam time as possible before the facility shuts down.
Come 7 a.m. on April 10, phase one of the removal project begins. The Accelerator Systems Division will secure the facility for component removal, with an emphasis on preserving as many components as possible. Carefully considering safety issues, crews will work systematically to identify components and then disconnect electrical, water, and protection systems for the FFTB with minimal interference to ongoing linac operations. Researchers will come in during phase one to remove their experimental equipment.
Phase two will begin May 1 under the direction of the LCLS Construction Directorate. A professional rigging subcontractor will remove all remaining items. That includes about 3,000 tons of concrete shielding—some individual pieces 60-feet long and 38 tons—support structures and up to 250 magnets. All the magnets will be reused at LCLS or other lab facilities.
In early to mid July, the Research Yard will be turned over to the LCLS Construction Manager General Contractor to begin construction in that area. The LCLS Beam Transport Hall will carry electrons from the linac, through the Research Yard, to the underground Undulator Hall, where ultrafast x-rays will be generated. The BTH will be 218 meters long and 27 feet wide.
-- Heather Rock Woods