Smaller accelerators continue the search for dark matter

Nature : In the wake of the null results from the Large Hadron Collider (LHC) at CERN, some physicists are turning from larger, more powerful particle accelerators to smaller, less expensive ones. At the Thomas Jefferson National Accelerator Facility in Virginia, a continuous dense beam of electrons races around a track, as opposed to the series of higher-energy pulsed beams typically used in many accelerators, including the LHC. Amid the cascade of short-lived particles created when the beam crashes into a thin tungsten target, researchers are hoping to detect evidence of such rare particles as heavy, or dark, photons. Discovery of dark photons could be a first step toward understanding the dark matter that is thought to make up 85% of the matter in the universe. Although experiments like the one at Jefferson Lab are considered a long shot, “it could be that these much smaller, faster, cheaper, upstart, high-intensity, low-energy experiments might actually dig up evidence for new physics before the big monsters,” says Nima Arkani-Hamed, a theorist at the Institute for Advanced Study in Princeton, New Jersey.