Experiment to Turn Light Into Matter

Scientists have worked out an easy way of turning light into matter, a process thought to be impossible when first proposed 80 years ago.

The proposed experiment, reported in the journal Nature photonics, would recreate events that occurred in the first 100 seconds of the big bang, as well as in cosmic rays and gamma ray bursts.

In 1934, scientists Gregory Breit and John Wheeler suggested light can be converted into matter by smashing two photons together to create an electron and its antimatter counterpart, a positron.

Breit and Wheeler's calculations were correct, but they never expected anyone to physically demonstrate their prediction.

"The Breit-Wheeler process is one of the simplest interactions of light and matter and one of the purest demonstrations of E=mc2," said the study's lead author Oliver Pike of Imperial College London.

"However, Breit-Wheeler pair production has never been observed. The experimental design we propose can be carried out with relative ease and with existing technology."

Just add gold

The photon collider would convert light directly into matter by using an extremely powerful high intensity laser to fire electrons at almost the speed of light into a slab of gold. This created a beam of photons a billion times more energetic than visible light.

The next step involves firing a separate high energy laser onto the surface of a tiny gold cylinder called a vacuum hohlraum (German for hollow cavity), to create a thermal radiation field of photons.

The researchers would then direct the photon beam from the gold slab through the center of the hohlraum, causing the photons from the two sources to collide and create electrons and positrons, which could be detected as they beamed out of the device.

Matter was first created out of pure energy in 1997 at the Stanford Linear Accelerator Center when a powerful electron beam was fired into a laser beam of photons.

Occasionally an electron collided with a photon pushing it into other photons with enough force to produce an electron and a positron.

"There was not enough energy at Stanford to observe the Breit-Wheeler process, instead a much more complex process was observed -- high-energy photons interacted with multiple low-energy photons in a strong laser field," said Pike.

"In our work, there are no massive particles present. Our scheme would therefore represent the first proof-of-principle of a pure photon-photon collider."

Easier way

Associate Professor Martin Sevior, an experimental particle physicist at the University of Melbourne, agrees.

"This new method won't require such high energy electron beams as those used by Stanford," said Sevior, who was not involved in the research.

"The Stanford experiment used the world's most intense and highest energy electron beam. This new system will work with a much lower energy electron beam, and it has a much greater photon yield for the same amount of energy."

Read more at Discovery News