Laser blasting antimatter into existence

November 5, 2018, American Physical Society
Radiation emitted by highly-relativistic electrons. Some electrons lose 80 percent of their energy in a single emission. This gamma-ray beam is very narrow: if you would point it to a wall of a house on the other side of the street, it would make a spot smaller than your fingertip. Credit: Marija Vranic, Instituto Superior Técnico, University of Lisbon.

Antimatter is an exotic material that vaporizes when it contacts regular matter. If you hit an antimatter baseball with a bat made of regular matter, it would explode in a burst of light. It is rare to find antimatter on Earth, but it is believed to exist in the furthest reaches of the universe. Amazingly, antimatter can be created out of thin air—scientists can create blasts of matter and antimatter simultaneously using light that is extremely energetic.

How do scientists make ? When electrons, negatively charged , move back and forth they give off light. If they move very fast, they give off a lot of light. A great way to make them move back and forth is to blast them with powerful laser pulses. The electrons become almost as fast as light, and they generate beams of gamma-rays (Figure 1). Gamma-rays are like X-rays, such as those at doctor's offices or airport security lines, but are much smaller and have even more energy. The light beam is very sharp, about the thickness of a sewing needle even a few feet away from its source.

When gamma-rays made by electrons run into each other, they can create matter-antimatter pairs—an electron and a positron. Now, scientists have developed a new trick to create these matter-antimatter pairs even more efficiently.

"We developed an 'optical trap' which keeps the from moving too far after they emit gamma-rays," said Marija Vranic from the University of Lisbon, who will be presenting her work at the American Physical Society Division of Plasma Physics meeting in Portland, Ore. "They get trapped where they can be hit again by the powerful laser pulses. This generates more gamma-rays, which creates even more pairs of particles."

This process repeats, and the number of pairs grows very fast in what is called a "cascade." The process continues until the particles that have been created are very dense (Figure 2).

An optical trap for matter-antimatter plasma. The trap is formed by 4 lasers, arranged in one plane, all going towards the same point. When the lasers overlap, they form a 2D wave, with electric fields shown in the figure. There is a tiny object in the center, a nanowire 100x thinner than a human hair. The electrons are stripped off the wire and accelerated close to the speed of light. They are trapped in the wave, so when they lose most of their energy by emitting light, they get re-accelerated. The photons produce electron-positron pairs, themselves trapped. This process can create a dense electron-positron plasma that eventually converts most of the available laser energy into gamma-rays. Credit: Marija Vranic, Instituto Superior Técnico, University of Lisbon

Cascades are thought to occur naturally in faraway corners of the universe. For example, rapidly rotating neutron stars called pulsars have extremely , a trillion times stronger than the magnetic fields on Earth, that can produce cascades.

Studying cascades in the laboratory could shed on mysteries related to astrophysical plasmas in extreme conditions. These beams can also have industrial and medical applications for non-invasive high-contrast imaging. Further research is necessary to make the sources cheaper and more efficient, so that they can become widely available.

Explore further: Antimatter plasma reveals secrets of deep space signals

Related Stories

Antimatter plasma reveals secrets of deep space signals

July 17, 2018

Mysterious radiation emitted from distant corners of the galaxy could finally be explained with efforts to recreate a unique state of matter that blinked into existence in the first moments after the Big Bang.

Scientists one step closer to mimicking gamma-ray bursts

May 27, 2015

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such as black holes ...

Recommended for you

Terahertz laser pulses amplify optical phonons in solids

November 15, 2018

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg/Germany presents evidence of the amplification of optical phonons ...

Bursting bubbles launch bacteria from water to air

November 15, 2018

Wherever there's water, there's bound to be bubbles floating at the surface. From standing puddles, lakes, and streams, to swimming pools, hot tubs, public fountains, and toilets, bubbles are ubiquitous, indoors and out.

Designer emulsions

November 15, 2018

ETH material researchers are developing a method with which they can coat droplets with controlled interfacial composition and coverage on demand in an emulsion in order to stabilise them. In doing so they are fulfilling ...

Quantum science turns social

November 15, 2018

Researchers in a lab at Aarhus University have developed a versatile remote gaming interface that allowed external experts as well as hundreds of citizen scientists all over the world to optimize a quantum gas experiment ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.