LHC: A high energy, high luminosity muon-hadron collider at CERN
This paper presents the feasibility study and scientific potential of the LHC, a proposed high-energy, high-luminosity muon-hadron collider at CERN that repurposes LHC infrastructure to achieve center-of-mass energies up to 7.5 TeV and offers unique synergies with other major collider projects.
Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Deep in the heart of particle physics, scientists are constantly trying to build machines that can smash tiny particles together with enough force to reveal the fundamental rules of the universe. For decades, the most successful tool for this has been the collider, where beams of particles are accelerated to near the speed of light and then crashed into one another. The current champion of this field is the Large Hadron Collider at CERN, which smashes protons together to find new particles like the Higgs boson. However, to see even deeper into the fabric of reality, physicists need to collide different types of particles. Specifically, they are interested in smashing muons, which are heavy cousins of the electron, against protons. This specific combination offers a unique window into the structure of matter and the forces that hold it together, potentially revealing physics that current machines cannot see. The challenge has always been that muons are unstable and decay very quickly, making them incredibly difficult to capture, cool down, and accelerate to the high speeds required for a collision.
A new proposal, detailed in a recent study by a group of researchers known as HELP4CERN, outlines a bold plan to overcome these hurdles by building a muon-proton collider at CERN. The team suggests a machine they call LH𝜇C, which would reuse much of the existing infrastructure from a proposed electron-proton collider, the LHeC, to create a facility capable of smashing a beam of muons into a beam of protons. The plan involves taking a beam of protons, hitting a target to create pions, and then capturing the resulting muons. Instead of the traditional methods used to cool these particles, the proposal relies on a newer technique developed in Japan that uses a special type of glass-like material called aerogel to slow the muons down to a near standstill. Once cooled, these ultra-cold muons are accelerated to energies of one or two trillion electron volts and then injected into a storage ring where they collide with the seven-trillion-electron-volt proton beam circulating in the Large Hadron Collider. This setup would create a collision energy of up to 7.5 trillion electron volts, a level of power that would make it a factory for producing heavy particles like the top quark and the Higgs boson with unprecedented precision.
The researchers have mapped out exactly how this machine would work, from the source of the muons to the detectors that would record the results. The design envisions a system where the muons are accelerated in stages, using a novel type of accelerator that keeps the particles on a fixed path while increasing their speed, before they are transferred into a main ring that runs alongside the existing proton ring. When the beams finally meet, the collision would happen at a rate of four million times per second, with the potential to produce a staggering number of events for scientists to study. The paper suggests that even with a conservative estimate of how many muons can be produced, the machine would be powerful enough to explore a vast new territory of physics. It would allow scientists to probe the internal structure of protons with a level of detail that is currently impossible, looking for signs of new forces or particles that lie beyond our current understanding.
Beyond the collisions themselves, the project offers a surprising bonus. As the muons travel through the machine, they naturally decay into neutrinos, creating an incredibly intense and focused beam of these ghostly particles. This would provide Europe with a unique and powerful platform for neutrino science, allowing researchers to study these elusive particles in ways that are not possible with current technology. The study also addresses the practical challenges of building such a machine, including how to shield the detectors from the background noise caused by decaying muons and how to design a detector that can handle the unique conditions of a muon-proton collision. While the paper presents a detailed concept and shows that the physics goals are achievable, it acknowledges that the technology for producing and accelerating the muons is still being developed and tested. The proposal serves as a roadmap, demonstrating that with the right combination of existing technology and new innovations, a high-energy muon-proton collider could become a reality, opening a new chapter in our understanding of the universe.
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