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The Underground Panoramas of SLAC

The tunnel is prepped for the final breakthrough
by Brad Plummer
The tunneling breakthrough into the Far Experimental Hall (FEH) of the Linac Coherent Light Source (LCLS) on January 14th was the culmination of months of planning and excavation work. Having begun nearly a year ago, the FEH cavern is nearly complete, with only the pouring of the concrete slab floor remaining. Once the floor is poured, construction of the experimental hutches can begin.

The cavern, which measures 50 feet wide, 35 feet tall, and 230 feet long, was excavated in sectioned layers, starting from the top. Over the course of FEH excavation, as each bench was removed, tunneling subcontractor Tolga Togan of Affholder Incorporated documented the process with his camera to create this series of panoramas of the cavern and the road header at work.

Panorama
Working to finish the FEH top heading, which is the ceiling. The road header worked from top to bottom in layers to excavate the FEH. (Click on image for larger version.)

Panorama
Looking directly into the access tunnel, the FEH appears curved in this panorama. Each end is visible as the road header removes the next layer of earth. (Click on image for larger version.)

Panorama
Looking westward, with the access tunnel on the right, and the east end of the FEH out of frame. Removal of the second layer nears completion. (Click on image for larger version.)

Panorama
After removal of the last wall of earth (far left) one layer remains to reach the final floor of the FEH. (Click on image for larger version.)

Panorama
Excavation is now complete, and the site is prepped for the final breakthrough, which took place just after this shot. (Click on image for larger version.)
Questions? Comments? You can contact the author at bplummer@slac.stanford.edu.