A negatively charged hydrogen ion accelerates down a linac to nearly a billion electron volts—90% of the speed of light—and punches through graphite foil that strips off the ion’s two orbiting electrons. The resulting proton enters a ring where it and other protons are stored and accumulated into pulses that are fired at 60 Hz toward a vessel of liquid mercury. In a process known as spallation, the protons collide with atomic nuclei in the heavy metal and knock out short, intense pulses of neutrons. Those neutrons are then guided through as many as 24 beamlines to the myriad instruments and detectors used for experiments.
That’s the vision behind the Spallation Neutron Source (SNS), a $1.4 billion facility nearing completion at Oak Ridge National Laboratory (ORNL). Currently in its testing phase, the facility is expected to produce the most intense pulsed neutron beams in the world, with each pulse yielding...
