The DOE's SLAC linear accelerator, or "linac," stretches in a straight line for two miles across the hills of Stanford University in Menlo Park, California. The building shown in the photo -- known as the "klystron gallery" because it houses machines called klystrons that power the accelerator -- is the longest modern building in the world. The particle accelerator itself is a copper tube roughly 20 feet below ground and has been used to accelerate electrons and positrons for over 50 years of world-leading scientific experiments. | Photo courtesy of SLAC National Accelerator Laboratory.

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