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If you've ever heard the thunderous sound of a sonic boom, you've experienced the shock waves in the air created by an object traveling faster than the speed of sound. But what happens when an object travels faster than the speed of light? At Jefferson Laboratory, construction is underway to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) and the CEABF Large Acceptance Spectrometer (CLAS12) at Hall B. During the experiments, the accelerator will shoot electrons at speeds faster than the speed at which light travels in the same medium, creating shock waves that emit a blue light, known as Cherenkov light -- this light is equivalent to the sonic boom. By recording data from Cherenkov light, scientists will be able to map a nucleon's three-dimensional spin. The device will use 48 ellipsoidal mirrors assembled into one circular, 8-foot diameter mirror to capture this light. Pictured here is the web-like component that will support the mirrors in the accelerator itself. | Photo courtesy of Jefferson Laboratory.