Positive muons accelerated, ‘tamed’ for the first time using controlled beam

Scientists have been trying to accelerate muons for decades, but these elusive fundamental particles almost always undergo decay before reaching their full speed.

With a lifespan of only two microseconds (2 x 10 ^-6 sec) and an annoying habit of moving around in different directions, it becomes very challenging for scientists to accelerate muons even using a powerful beam.

“Muons are fiendishly difficult to accelerate because they only exist for around 2 microseconds before they decay into an electron and two types of neutrino. They also dart around in different directions at various speeds, making them difficult to tame into a narrow, high-intensity beam,” Shusei Kamioka, an expert in particle physics, said.

However, researchers from the Japan Proton Accelerator Research Complex (J-PARC) claim to have successfully accelerated muons for the first time .

The trick is to make antimuons from muoniums

Muons are almost the same as electrons, but they are 200 times heavier and undergo decay very quickly. In order to overcome these challenges and accelerate them, J-PARC researchers performed an interesting experiment.

They fired a highly controlled beam of antimuons (positively charged muons) into a spongy silica aerogel that works as a thermal insulator. The collision between antimuons and electrons in the aerogel led to the creation of muonium atoms (muonium is a short-lived particle made up of a muon and an electron).

Next, to eliminate the electrons from muonium atoms, the researchers used a laser beam. This again turned muoniums into antimuons, which were instantly frozen to keep them static.

When the researchers employed an electric field with energies ranging between 5.7 and 100 kiloelectronvolt (keV) to accelerate the stationary positive muons, the particles moved at four percent the speed of light (~12 million meter/second) — a feat that had never been achieved before.

This achievement marks a significant step towards the realization of muon colliders, which hold the potential to revolutionize particle physics research.

“We are developing the technology needed to accelerate muons to 94% of the speed of light, and hope to achieve this by 2028. That is our next milestone,” Kamioka said .

The significance of muon acceleration

Once muon acceleration becomes scalable, this could lead to the development of specialized particle accelerators called muon colliders.

These advanced research tools could facilitate the discovery of new particles , contribute to medical treatments, and enhance our understanding of natural phenomena that govern the universe.

“Besides building a future collider, physicists could use high-energy muon beams in experiments that could go beyond the standard model of particle physics, such as precisely measuring the muon’s mysterious magnetism — which is stronger than predicted by theory,” Kamiake explained.

The study is published on arXiv and is yet to be peer-reviewed.