Proposed experiment would create matter from light

Collider would convert photons into electrons and positrons

A proposed experiment may soon transform particles of light into matter.

Oliver Pike, a plasma physicist at Imperial College London, typically works on nuclear fusion — a process that converts matter into energy and not vice versa. But he and his colleagues laid out plans for a device that would use a key piece of fusion equipment to convert light, a form of energy, into particles with mass. It would do so by smashing photons together to create electrons and their antimatter counterparts, positrons. Physicists have never observed this process in the lab.

Detailed May 18 in Nature Photonics, the design relies on a hohlraum, a small metal cylinder that holds hydrogen fuel in laser fusion experiments (SN: 4/20/13, p. 26). Heating a hohlraum with a laser produces a dense field of X-ray photons inside. Pike’s team estimates that passing a jet of high-energy gamma-ray photons through the laser-excited hohlraum would make enough photons collide to produce up to 100,000 pairs of electrons and positrons.

The experiment requires two powerful lasers and vacuum conditions, so it can’t be done in just any lab. But Pike says several scientists are interested in trying it out. He hopes someone will start colliding photons within a year.

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