TACC Stampede, Lonestar supercomputers help discover gamma ray creation from lasers
Ever play with a magnifying lens as a kid? Imagine a lens as big as the Earth. Now focus sunlight down to a pencil tip. That still wouldn’t be good enough for what some Texas scientists have in mind. They want to make light even 500 times more intense. And they say it could open the door to the most powerful radiation in the universe: gamma rays.
Comic book readers might know about gamma rays. The Incredible Hulk was transformed from mild scientist into wild superhero by gamma rays from a nuclear explosion. The real gamma rays form in nature from radioactive decay of the atomic nucleus. Besides hazardous materials, you’d have to look in exotic places like near a black hole or closer to home at lightning in the upper atmosphere to find natural forces capable of making gamma rays.
Scientists have found that gamma rays, like the Hulk, can do heroic things too — if they can be controlled. Hospitals now eradicate cancer tumors using a ‘gamma ray knife’ with surgical precision. The rays can also image brain activity. And gamma rays are used to quickly scan cargo containers for terrorist materials. But it’s near impossible to make gamma rays with non-radioactive materials. To do that today one needs a colossal atom smasher like at CERN or SLAC. No one has been able to make a gamma ray beam from lasers. But it can be done, say scientists at The University of Texas (UT) at Austin.
Supercomputers might have helped unlock a new way to make controlled beams of gamma rays from a laser that fits on a table-top, according to research physicist Alex Arefiev, who has a dual appointment at the Institute for Fusion Studies and at the Center for High Energy Density Science at UT Austin. Arefiev co-authored the study, “Enhanced multi-MeV photon emission by a laser-driven electron beam in a self-generated magnetic field,” published May 2016 in the journal Physical Review Letters.
“One of the key results that we found is that a laser pulse can be efficiently converted into a beam of very energetic photons,” Arefiev said. “They are more than one million times more energetic than the photons in the laser pulse. Until recently, there hasn’t been a method for producing a beam of such energetic photons. So the proposed regime can be groundbreaking for a number of applications and also for fundamental science studies.”