Particle colliders that could reach collision energies much higher than existing facilities, such as the Large Hadron Collider, could be a step closer to being possible, according to research published in Nature. The study reports improvements to the delivery of a beam of muons — fundamental particles like electrons but with higher masses. The all-important collision energies that can be reached scale with mass, so muon colliders are expected to be smaller — and hence potentially less costly — than current colliders.
Fundamental particles, such as electrons and muons, are ideal for probing the structure of matter because they do not have substructures, which means that they carry the full energy of the beam in particle collision experiments. Muons are 207 times more massive than electrons, which could allow collisions at greater energies than are achievable with current accelerators. However, muon beams cannot yet be prepared with the properties needed to implement such collision experiments.
Chris Rogers and colleagues overcome some of the challenges associated with producing the high-brightness muon beams needed for high-energy collision experiments by realizing ionization cooling of muons. This achievement helps to reduce excess movement in the wrong direction, and could help to produce a muon beam of high enough quality to enable the search for phenomena beyond the reach of existing colliders. In an accompanying News & Views article, Robert Ryne suggests that these results represent a milestone on the road to muon colliders, but notes that much work is still needed before such facilities could be realized.
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