Muon accelerators can now be a reality with this new breakthrough

Particle accelerators like the famous Large Hadron Collider (LHC) reveal the origin of matter and help us understand the universe’s makeup. Scientists use these giant machines to find answers related to elementary particles, dark matter, energy, antimatter, etc.

Inside a particle accelerator , charged particles like protons or electrons are made to move at very high speeds. These fast-moving particles are then directed to collide with targets or with each other. By studying the results of these collisions, scientists can learn about the basic building blocks of matter and the forces that hold them together.

However, there are several challenges with particle accelerators. For instance, they are very expensive to build and require a large space for their operations.

Interestingly, physicists have known for some time that using muons (elementary particles similar to the electron but with a much greater mass) instead of ions, protons, and electrons can make particle accelerators better, cheaper, and smaller.

But the challenge with this approach has been identifying a practical way to use muons as a beam within a particle accelerator. Finally, a new study by MICE collaboration researchers reveals a way to achieve this.

Overcoming a key challenge, they have discovered a method to increase the density and location of muons in a beam, making them easier to control and collide in a particle accelerator.

Notably, the MICE (Muon Ionization Cooling Experiment) collaboration is an international scientific project focused on developing the ionization cooling technique for muons.

Cooling muon beams makes them easy to handle

Although muons are heavy particles, they are highly unstable and decay into electrons and neutrinos within 2.2 microseconds of their origin.

This makes it difficult to keep them together in an accelerator long enough to form a concentrated beam and undergo collision. Additionally, their short lifespan means they need to be gathered and accelerated quickly before they decay.

During their previous study, the authors learned to arrange muons in the form of a beam using materials that reduced the energy of the muons. They also employed a magnetic lens to focus and keep the muons in the central region of the beam.

This time, they studied the shape of the beam and discovered that cooling a muon beam decreases the space it occupies. Plus, it also enables the muons to move in a well-aligned manner. “The phase-space volume of the muon beam can be decreased through ionization cooling,” the study authors note.

They also conducted an experiment using a small prototype accelerator, showing the formation and cooling of a high-brightness muon beam. “The clear positive result shown by our new analysis gives us the confidence to go ahead with larger prototype accelerators that put the technique into practice,” said Ken Long, one of the study authors and a MICE scientist.

Advantages of a muon accelerator

The MICE collaboration comprises hundreds of scientists, all working together to turn muon accelerators (particle accelerators that use muons) from a theoretical concept into reality.

This is because, compared to conventional particle accelerators, muon accelerators offer several advantages. For instance, “if built, a future muon collider could provide 10 times the discovery reach of CERN’s Large Hadron Collider even after its substantial upgrade,” according to the Fermilab at the US Department of Energy.

Currently, the LHC ’s circumference measures around 17 miles (27 km), and it will be expanded to approximately 56 miles (90 km). With a muon collider, scientists can conduct high-energy collisions in a smaller space at lower costs.

“A muon collider would be more compact and therefore cheaper, reaching effective energies as high as those proposed by the 90km proton collider in a much smaller space,” the study authors added.

However, currently, no operational muon accelerator exists. The current study solves one of the key challenges with the realization of this technology, but the researchers still need to do a lot of work.

The next goal of the MICE team is to develop an effective cooling system for future muon accelerators.

The study is published in the journal Nature Physics .