The Final Focus Test Beam (FFTB) 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 (BTH) for the Linac Coherent
Light Source (LCLS).
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 are underground, and the remainder is visible as a long concrete
A birdís 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.
(Image courtesy of Heather Rock Woods)
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 are 60-feet long and weigh 38 tons),
support structures and up to 250 magnets. All the magnets will be reused
or other Lab facilities.
In early to mid-July, the LCLS Construction Manager General
Contractor will begin construction in that area. The BTH 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