New Report: U.S. Should Begin Development of World’s Most Powerful Particle Collider

A new report from the National Academies of Sciences, Engineering, and Medicine presents an ambitious and comprehensive long-term vision for the field of particle physics to further our understanding of matter, energy, space, and time. In particular, it calls for the U.S. to begin a national research and development program aimed at building a muon particle collider within the next 40 years, and highlights the need to continue pursuing newer approaches to particle physics, including with sensitive underground arrays that can detect dark matter signatures, telescopes that provide cosmological data, and nuclear reactors to aid in neutrino research.

The U.S. is well positioned to continue leading in particle physics research and development over the coming decades, the report says – and it credits the nation’s current global standing to scientific collaboration, material resources, expert workforce, and long-standing sponsorship from federal agencies including the U.S. Department of Energy and the National Science Foundation. Staying at the scientific forefront will require sustained investments in research in general and funding for accelerator science and technology, advanced instrumentation, all aspects of computing, emerging technologies from other disciplines, and a healthy core particle physics research program.

“U.S. particle physics leadership is distinguished by both the breadth and depth of its program, from major participation in the Large Hadron Collider at CERN and the muon and neutrino programs hosted at Fermilab to ultra-sensitive underground experiments and multiple cosmic surveys,” said Michael Turner, a visiting professor at UCLA and Rauner Distinguished Service Professor Emeritus at the University of Chicago, and co-chair of the committee that wrote the report. “This unsurpassed program of particle physics research is enabled by a strong and unique partnership between our national laboratories, university researchers, and industry.”

World’s Most Powerful Particle Collider

The report calls for the U.S. to develop the world’s highest-energy elementary particle collider. The collider would, in an as-yet-untried scientific feat, accelerate muons — unstable elementary particles often characterized as the heavier cousins of electrons — to nearly the speed of light. A muon collider offers benefits for subatomic exploration that are not readily available from a proton collider of similar scale — it could have 10 times as much power as the Large Hadron Collider, despite being a much smaller size. Such a project would require extensive research and development that must begin now, along with international coordination and the construction of a demonstrator project to prove its practical feasibility.

Beyond Colliders

Colliders are and will remain essential to advancing particle physics, but more recent forays have diversified the field’s approaches for tackling its fundamental questions, through research into the cosmic microwave background of the universe, dark matter, neutrinos, gamma rays, and other areas of physics. The report says that the U.S. has the world’s leading program in non-collider particle physics, largely thanks to Department of Energy national laboratories with high-energy physics programs and their extensive partnerships with university programs. The U.S. should continue its support for these other research avenues due to their faster implementation times, scientific value, and the opportunities they provide to early-career scientists.

Basic research into particle physics has produced a great deal of long-term value, finding applications across other sciences as well as in society and the economy. Particle physics has benefited from progress in other fields, and in turn has served as a test bed and incubator for cutting-edge areas of science like exascale computing and AI and machine learning methodologies.

The field’s interconnections with other fields such as microelectronics, nuclear physics, astronomy, and quantum engineering continue to grow, creating compelling synergistic opportunities. The report says that the U.S. government should help advance all these fields and the domestic development of next-generation science and technologies by creating new partnerships across disciplines and previous funding boundaries.

International Partnerships

"The coming decades in particle physics promise deep exploration, expanding knowledge, and technological breakthroughs, benefiting science, the nation, and humanity,” said committee co-chair Maria Spiropulu, Shang-Yi Ch’en Professor of Physics at the California Institute of Technology. “The U.S. must sustain its leadership by capitalizing on these advances, which demands sustained investment in a highly skilled workforce, cultivation of the next generation of innovators, and the new instruments essential for progress. Crucially, the U.S. will strengthen its position by strategically investing in international partnerships that benefit our scientists and bolster our global project capabilities.”

Following on the successful discovery of the elusive Higgs boson, the report specifically urges the U.S. to participate in the development and building of a “Higgs factory.” The concept is currently under study as the Future Circular Collider at the European Organization for Nuclear Research (CERN). U.S. participation in this international effort would be beneficial both for the success of the effort and for the health of the field, the report says. The pursuit of this collider, which could produce millions of Higgs particles at a time, would help researchers determine whether it is an elementary particle or has a further substructure, pushing the boundaries of exploration at the subatomic level.

Workforce of the Future

Particle physics is marked by large projects such as the Future Circular Collider or muon collider with timescales measured in decades, so long-term sustainment of the field’s workforce is essential for progress. But the report finds that the current system for recruiting, training, and progressing the careers of students and postdoctoral particle physicists is under stress both from trends affecting the broader STEM workforce and more unique factors.

The field is facing looming workforce shortfalls in part because Ph.D.-level physics degree holders are increasingly in demand in other technical fields, and particle physics experts are valued by private industry for their ability to contribute to innovation. Reaching the field’s ambitious science goals will require the community to take greater levels of responsibility for recruiting, training, mentoring, and retaining students and the workforce, and the federal government should provide the means for it to do so, the report says.

The study — undertaken by the Committee on Elementary Particle Physics — was sponsored by the U.S. Department of Energy and the National Science Foundation.