Setting the stage: MAP scientists lay out plans for a future muon collider

The Muon Accelerator Program collaboration met at Fermilab in June to explore the staging possibilities for a future muon collider. Photo: Reidar Hahn

The future of Fermilab’s campus may rely on the interactions not only of particles, but also of frontiers: the Energy and Intensity frontiers.

This is the idea behind the Muon Accelerator Program, a collaboration designed to study the possibility of a future neutrino factory and muon collider. The MAP collaboration met at Fermilab in June to, among other things, kick off its Muon Accelerator Staging Study, headed by Jean-Pierre Delahaye of SLAC National Accelerator Laboratory. Also at the meeting were Steve Brice and Dmitri Denisov, who in March were officially named Intensity Frontier program scientist and Energy Frontier program scientist, respectively.

“The reach of MAP is unique in that it can support world-class physics on both the Energy and Intensity frontiers,” said Mark Palmer, director of MAP. “The purpose of this meeting is to develop that vision and support that effort.”

The completion of MAP’s ultimate end goal—a multi-TeV muon collider—is likely more than 20 years into the future. But instead of proposing a 20-year, multi-billion-dollar project, the team is considering a series of staged facilities that could be built with smaller amounts of time and money. Each stage would produce good physics on its own while contributing to the development of the whole.

“The staged approach is more realistic to get resources, and at the same time it helps to develop, test and validate gradually the technology necessary for the next stages, thus allowing an informed decision before embarking upon each subsequent stage,” Delahaye said.

As particles travel around an accelerator ring, they emit synchrotron radiation—the lighter the particle, the more radiation it emits. A linear collider solves the radiation problem but is far less efficient than a ring. Colliding muons in a ring solves both problems: Because muons are far heavier than, say, electrons, they can travel in a ring without producing significant amounts of synchrotron radiation.

“The hope is that MAP would at various times give us world-leading machines both on the Intensity Frontier with a neutrino factory and then on the Energy Frontier with a new colliding machine, a muon collider,” Brice said.

The proposed first experiment in the process is called nuSTORM, a low-intensity muon storage ring that would support a high-precision, short-baseline neutrino oscillation experiment using muon beams. MAP scientists advocate the use of nuSTORM as a platform for the development of advanced muon accelerator technology. Advised by the Fermilab Physics Advisory Committee, the laboratory director accepted the proposal for nuSTORM in late June.

This experiment could then be followed by a long-baseline neutrino factory, NuMAX, which would be driven by the Project X Phase 2 negatively-charged-hydrogen ion linac and point toward the Sanford Underground Research Facility in Lead, SD. The infrastructure implemented for this facility could then serve as a foundation for the next collider operating at Fermilab.

Laura Dattaro