The 2-mile electron microscope

9 September 1998

On September 9, 1967 the 2-mile (about 3 km) long linear accelerator, or linac, at the Stanford Linear Accelerator Center (SLAC) in California was officially dedicated. According to the SLAC archives, in a message by telegram, the US President Lyndon Johnson said "this magnificent machine has begun its working life…on time, within budget estimates and with even higher energy than design." The machine initially accelerated electrons to energies of 20 GeV (gigaelectron volts), but now after several upgrades it accelerates both electrons and their antimatter equivalents positrons, to energies of 50 GeV. Over the years, the machine has brought three Nobel Prizes to the laboratory, one of its first major achievements being to demonstrate the reality of a new layer of matter - the quarks - within the more familiar protons and neutrons of the atomic nucleus.

Credit: SLAC

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