From SLAC: “SLAC’s Electron Hub Gets New ‘Metro Map’ for World’s Most Powerful X-Ray Laser”


July 5, 2017
Manuel Gnida

A reconfiguration of SLAC’s historic Beam Switch Yard will include electron transport lines needed for LCLS-II, a major upgrade to the Linac Coherent Light Source (LCLS) X-ray laser. (Greg Stewart/SLAC National Accelerator Laboratory)

The central hub for powerful electron beams at the Department of Energy’s SLAC National Accelerator Laboratory is getting a makeover to prepare for the installation of LCLS-II – a major upgrade to the Linac Coherent Light Source (LCLS), the world’s first hard X-ray free-electron laser. LCLS-II will deliver the most powerful X-rays ever made in a lab, with beams that are 10,000 times brighter than before, opening up unprecedented research opportunities in chemistry, materials science, biology and energy research.

Central portion of the BSY before (left) and after the Reconfiguration Project. (Scott DeBarger/SLAC National Accelerator Laboratory)

A Monumental Clean-up Operation

To clear the path for LCLS-II, crews first had to remove all unnecessary materials from the BSY – a monumental task considering SLAC’s rich history in accelerator science and the legacy material it created.

“When experiments end, most of the old equipment is typically left in place,” says SLAC’s Mark Woodley, an optics designer involved in the BSY Reconfiguration Project. “Only the things that are in the way of new experiments are taken out.”

In its early days in the 1960s, the linac delivered electron beams to three experimental stations. There was one line going straight into the lab’s research yard. Today this line continues to the LCLS undulator. Pulsed magnets in the BSY could divert the beam into End Stations A and B via two beamlines that branched off the central line.

In 1980, two more branches were added to feed electrons and positrons, the antiparticle siblings of electrons, into the two storage rings of the PEP accelerator (PEP-II from 1999). In 1987, another two branches were needed to deliver beams to the two arms of the Stanford Linear Collider (SLC).

Most of the old materials left behind in the BSY by these experiments have now been cleared – a job that took 300 employees and subcontractors almost 24,000 hours of work in the period from December 2016 to May 2017. They removed 325 cubic yards, or about 24 tons, of material – enough to fill eight sea-land shipping containers – and more than 300,000 feet of cables.

“Considering the monumental task we had ahead of us, it’s truly impressive how well this project went,” DeBarger says. “It involved many people from inside and outside the lab, and every single one of them was absolutely needed.”

Building the Future of X-ray Science

After clearing out the BSY, members of the Reconfiguration Project installed a new beamline that runs from the copper linac to the current LCLS undulator. In parallel, the system to extract electrons for the End Station A line was put in place by another project team.

“We also installed the very first LCLS-II beam pipe at the end of a ‘muon shield’ that is constructed of 5- and 10-ton steel blocks and shields the beam transport hall downstream of the BSY, allowing access while beams are tuned in the BSY,” says Dean Hanquist, control account manager on Chan’s team.

“In the end, we had to make sure that everything works properly again for LCLS, which has now resumed its experimental program,” says BSY Area Physicist Tonee Smith. “For example, all of the magnets used in the beamline to focus the electron beam and make small corrections to it were refurbished, and we had to remeasure and test them.”

The remaining beamlines and junctions will be installed during a yearlong LCLS downtime, which will start in the summer of 2018. Once completed, the new BSY “metro system” will be ready to transport electron trains to the new X-ray laser facility, where they will power groundbreaking X-ray science for years to come.

Crew members gather at the conclusion of the BSY Reconfiguration Project. (Dawn Harmer/SLAC National Accelerator Laboratory)

For questions or comments, contact the SLAC Office of Communications at

The interior of the east portion of the Beam Switch Yard (BSY) showing three “tracks” that electrons accelerated in SLAC’s linear accelerator can be directed into. All of the beams for LCLS and LCLS-II are sent through the central tunnel. In early 2017, as part of the LCLS-II project, the steel Muon Shield was reconfigured to permit installation of a new beamline that will transport beams to a new Soft X-Ray Undulator. (Chris Smith/SLAC National Accelerator Laboratory)

Workers install the shield pipe that will position and protect the LCLS-II vacuum chamber within the Muon Shield. (Chris Smith/SLAC National Accelerator Laboratory)

Surveyors Bryan Rutledge and Francis Gaudreault measure the position of the LCLS beamline prior to its disassembly. (Chris Smith/SLAC National Accelerator Laboratory)

Mechanical Engineer Alev Ibrahimov, left, and Transport Systems CAM Dean Hanquist inspect the LCLS-II installation location in Sector 30. (Dawn Harmer/SLAC National Accelerator Laboratory)

Rigger Scot Johnson positions a movable hoist. (Chris Smith/SLAC National Accelerator Laboratory)

A crane removes the D-10 Tune-up Dump. This dump has five apertures, visible at the end of the device, which over the years allowed beams to head to various downstream experimental areas including LCLS, End Station A, End Station B and SPEAR. (Chris Smith/SLAC National Accelerator Laboratory)

See the full article here .

Please help promote STEM in your local schools.


Stem Education Coalition

SLAC Campus
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.