Nav: Home

Lawrence Livermore scientists 1 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 and gamma-ray bursts.

By performing experiments using three laser systems -- Titan at Lawrence Livermore, Omega-EP at the Laboratory for Laser Energetics, and Orion at Atomic Weapons Establishment (AWE) in the United Kingdom -- LLNL physicist Hui Chen and her colleagues created nearly a trillion positrons (also known as anti-matter particles). In previous experiments at the Titan laser in 2008, Chen's team had created billions of positrons.

Positrons, or "anti-electrons," are anti-particles with the same mass of an electron but with opposite charge. The generation of energetic electron-positron pairs is common in extreme astrophysical environments associated with the rapid collapse of stars and formation of black holes. These pairs eventually radiate their energy, producing extremely bright bursts of gamma rays. Gamma-ray bursts (GRBs) are the brightest electromagnetic events known to occur in the universe and can last from ten milliseconds to several minutes. The mechanism of how these GRBs are produced is still a mystery.

In the laboratory, jets of electron-positron pairs can be generated by shining intense laser light into a gold foil. The interaction produces high-energy radiation that will traverse the material and create electron-positron pairs as it interacts with the nucleus of the gold atoms. The ability to create a large number of positrons in a laboratory, by using energetic lasers, opens the door to several new avenues of antimatter research, including the understanding of the physics underlying extreme astrophysical phenomena such as black holes and gamma-ray bursts.

"The goal of our experiments was to understand how the flux of electron-positron pairs produced scales with laser energy," said Chen, who along with former Lawrence Fellow Frederico Fiuza (now at SLAC National Accelerator Laboratory) are the lead authors of an article are appearing in the May 18 edition of Physical Review Letters.

"We have identified the dominant physics associated with the scaling of positron yield with laser and target parameters, and we can now look at its implication for using it to study the physics relevant to gamma-ray bursts," Chen said. "The favorable scaling of electron-positron pairs with laser energy obtained in our experiments suggests that, at a laser intensity and pulse duration comparable to what is available, near-future 10 kilojoule class lasers would provide 100 times higher antimatter yield."

The team used these scaling results obtained experimentally together with first-principles simulations to model the interaction of two electron positron pairs for future laser parameters. "Our simulations show that with upcoming laser systems, we can study how these energetic pairs of matter-anti-matter convert their energy into radiation," Fiuza said. "Confirming these predictions in an experiment would be extremely exciting."

Antimatter research could reveal why more matter than antimatter survived the Big Bang at the start of the universe. There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely antimatter, and what might be possible if antimatter could be harnessed. Normal matter and antimatter are thought to have been in balance in the very early universe, but due to an "asymmetry" the anti-matter decayed or was annihilated, and today very little antimatter is seen.

In future work, the researchers plan to use the National Ignition Facility to conduct laser antimatter experiments to study the physics of relativistic pair shocks in gamma-ray bursts by creating even higher fluxes of electron-positron pairs.
-end-
The research was funded by LLNL's Laboratory Directed Research and Development program and the LLNL Lawrence Fellowship.

Chen and Fiuza were joined by Anthony Link, Andy Hazi, Matt Hill, David Hoarty, Steve James, Shaun Kerr, David Meyerhofer, Jason Myatt, Jaebum Park, Yasuhiko Sentoku and Jackson Williams from LLNL, AWE, University of Alberta, University of Rochester and University of Nevada, Reno.

Founded in 1952, Lawrence Livermore National Laboratory provides solutions to our nation's most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

DOE/Lawrence Livermore National Laboratory

Related Black Holes Articles:

Black holes sometimes behave like conventional quantum systems
A group of Skoltech researchers led by Professor Anatoly Dymarsky have studied the emergence of generalized thermal ensembles in quantum systems with additional symmetries.
Scientists may have discovered whole new class of black holes
New research shows that astronomers' search for black holes might have been missing an entire class of black holes that they didn't know existed.
Growing old together: A sharper look at black holes and their host galaxies
The 'special relationship' between supermassive black holes (SMBHs) and their hosts -- something astronomers and physicists have observed for quite a while -- can now be understood as a bond that begins early in a galaxy's formation and has a say in how both the galaxy and the SMBH at its center grow over time, according to a new study from Yale University.
Are black holes made of dark energy?
Two University of Hawaii at Manoa researchers have identified and corrected a subtle error that was made when applying Einstein's equations to model the growth of the universe.
Telescopes in space for even sharper images of black holes
Astronomers have just managed to take the first image of a black hole, and now the next challenge facing them is how to take even sharper images, so that Einstein's Theory of General Relativity can be tested.
Can entangled qubits be used to probe black holes?
Information escapes from black holes via Hawking radiation, so it should be possible to capture it and use it to reconstruct what fell in: if given time longer than the age of the universe.
How black holes power plasma jets
Cosmic robbery powers the jets streaming from a black hole, new simulations reveal.
The orderly chaos of black holes
During the formation of a black hole a bright burst of very energetic light in the form of gamma-rays is produced, these events are called gamma-ray bursts.
Mystery of coronae around supermassive black holes deepens
Researchers have used observations from the ALMA radio observatory to measure, for the first time, the strength of magnetic fields near two supermassive black holes at the centers of an important type of active galaxies.
Supermassive black holes and supercomputers
The universe's deep past is beyond the reach of even the mighty Hubble Space Telescope.
More Black Holes News and Black Holes Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.