Antimatter had long been considered the stuff of science fiction until it was produced in many experiments at CERN, as well as other particle accelerator colliders. Now, a team of researchers from Kyoto University in Japan has just discovered antimatter can be created into thin air, and all it takes is a lightning strike.
The gist of their experiment, featured yesterday (November 22) in the journal Nature, is that when a lightning bolt strikes, it can produce nuclear reactions, resulting in matter-antimatter annihilation.
The researchers, led by Teruaki Enoto, a physicist at the university’s Hakubi Center for Advanced Research and Department of Astronomy, based their work on the already proven theory that thunderclouds and lightning can produce an afterglow of gamma radiation.
With this in mind, they had the idea that these gamma rays might react in some way with the environmental elements in the atmosphere. And so, they set about testing their hypothesis.
“Lightning and thunderclouds are natural particle accelerators,” the scientists explain in their paper, showing that gamma rays emitted by lightning can react with molecules in the air.
This reaction, especially when it involves “very energetic gamma ray flashes,” can generate radioisotopes and even positrons, the antimatter equivalent of electrons, their study found.
“We have this idea that antimatter is something that only exists in science fiction. Who knew that it could be passing right above our heads on a stormy day?”
To verify their theory, the team started working on a series of small gamma-ray detectors as early as 2015. Once the detectors had been built, the researchers placed them in different areas along Japan’s western coast — which, Enoto says, is the perfect place to observe powerful lightning and thunderstorms.
Through a crowdfunding campaign, the team was able to gather more than enough funds to build additional detectors, which they set up along the northwest coast of Honshu, Japan’s largest island. All there was left to do next was waiting for a stroke of luck and, naturally, of lightning.
Luck finally struck at the beginning of this year, when four gamma-ray detectors installed in the city of Kashiwazaki, north-central Niigata Prefecture, picked-up a large gamma-ray spike during a lightning storm on February 6.
The surge of gamma rays was recorded immediately after a lightning strike a few hundred meters away, reports Phys.org.
According to Gizmodo, it was a pair of lightning strikes that triggered the four detectors, set up between 0.5 and 1.7 kilometers away (around a third of a mile to a mile).
The team analyzed the data and the energies of the emitted particles. What they uncovered was that the gamma rays created by lightning produced nuclear fission, knocking out neutrons from nitrogen molecules in the air.
The detectors identified three distinct bursts of gamma rays, each with a different duration. While the first burst lasted less than a millisecond, the second one was, in fact, a gamma-ray afterglow, which faded after several dozens of milliseconds.
“We could tell that the first burst was from the lightning strike. Through our analysis and calculations, we eventually determined the origins of the second and third emissions as well,” Enoto said in a statement.
The team points out the gamma-ray afterglow was produced by lightning reacting with atmospheric nitrogen. The gamma rays generated by lightning are powerful enough to kick a neutron off of nitrogen atoms, the researchers explain. This neutron is then reabsorbed by particles in the atmosphere, resulting in a gamma-ray afterglow.
Lastly, the third burst was a prolonged gamma ray line, which lasted about one minute, at an energy of 0.511 megaelectronvolts (MeV). This kind of energy signature would normally be seen from positrons and electrons after a nuclear reaction, notes ScienceAlert.
A nitrogen nucleus has 14 neutrons. When gamma rays take one of those neutrons away, the result is nitrogen-13, an unstable, radioactive isotope, shows LiveScience. The unstable nitrogen atoms break down and release positrons, which then collide with electrons in annihilation events releasing gamma rays, explains Enoto’s team.
Leonid Babich, an experimental physicist from the Russian Federal Nuclear Centre, agrees with Enoto’s findings. In a commentary on the recent study, also published in Nature, Babich describes the gamma-ray afterglow detected by Enoto’s team as “a conclusive indication of electron–positron annihilation.”
In his opinion, their study “represents unequivocal evidence that photonuclear reactions can be triggered by thunderstorms.”
However, just because Enoto proved lightning can generate radioactive particles in the sky, there’s no reason to panic. The physicist says there’s no cause for alarm, considering these radioactive isotopes “are short-lived, spatially restricted,” and produced in “a relatively small amount.”
“I think there is no health risk from this phenomenon,” Enoto clarifies in another statement.
[Featured Image by Tamas Kadar/Shutterstock]