Superman was cheated. X-ray vision isn’t where it’s at. If yesterday’s writers of comic books knew what we know today, the Man of Steel would have shot muons from his eyes to see through walls of stone.
Firing up the world’s most powerful laser at Romania’s Extreme Light Infrastructure Nuclear Physics (ELI-NP), a team of physicists generated a beam of high-energy particles called muons to image an object through meters of concrete.
As grainy and lacking in detail as they are, the “pictures” – presented in a paper available on the preprint website arXiv – represent a landmark advance in imaging technology that has applications in everything from security to mining.
Muons are electrons on steroids. These heavyweights are commonly generated when high-speed protons zoom through space and smash into atoms in our upper atmosphere, forcing them to cough up pairs of quarks called pions.
Pions quickly decay into muons, which themselves exist for a blink before decaying into their lighter-mass cousin (and some neutrinos).
Though their lives are short, muons that rain down from above survive just long enough to reach the surface. Thanks largely to their beefy mass, they easily pierce the ground, slipping through dense layers of rock and penetrating far deeper than even the most powerful of X-rays.
Archeologists and engineers have exploited these cosmic showers for decades, using muon-shine to search for signs of hollows within pyramids or mineral deposits deep underground.
Anyone who needs a muograph in a hurry or needs side-on images is out of luck. Muons strike the surface at a rather limited range of angles at a paltry rate of around one every square centimeter per second.
One way to artificially generate muons over practical distances is to use powerful lasers to rapidly accelerate electrons on waves of electromagnetism and smash them into a wall.
Last year, physicists in China, the US, and the UK used surfing electrons to produce muons, proving the technology was feasible.
Another international collaboration led by researchers from Lawrence Livermore National Laboratory and Colorado State University used the same method to create a flash of particles that imaged lead weights inside a truck. Just how many of those particles were muons isn’t clear, leaving the official “first pics” open to some debate.
The ELI-NP’s 10 petawatt laser is no flashlight. For a brief moment, its beam contains thousands of times the power of every power grid on the planet. That flash whips electrons along on waves until they collide with a lead barricade.
To sift out as many non-muon particles as possible, researchers developed a unique novel filter made of polyethylene sheets wrapped around paraffin blocks. From there, the beam of relatively pure muons was permitted to radiate through a two-meter (six-foot) wall of concrete and into an array of detectors inside a van parked on the other side.
After capturing the shadow of a pile of lead blocks, the team called it a win and claimed to have the first official muongraph produced artificially with a laser.
It’s no Polaroid, but with some development, the principles may one day be used to develop a smaller, transportable system that could look through the iron hulls of rockets or shipping transport, cores of rocky mountains, or the stone foundations of ancient structures with the ease of any superhero.
This research can be found on the preprint server, arXiv.
Source: Phys.org
