Haiyan Gao, vice chancellor for academic affairs at Duke Kunshan University and Henry Newson Professor of Physics at Duke University, participated in a recent study led by the National Academies of Sciences, Engineering, and Medicine which explores the significance of building an electron ion collider (EIC) in the United States.
The EIC, a very large-scale particle accelerator, would not only be significant to advancing understanding of the atomic nuclei that make up all visible matter in the universe, but also have far-reaching benefits to the United States’ science- and technology-driven economy, the report concluded.
The National Academies are private, nonprofit institutions based in the United States that provide expert advice on some of the most pressing challenges facing the United States and the world. At the request of the U.S. Department of Energy, the academies organized a committee, including physicists from Duke University, Massachusetts Institute of Technology, University of California, Berkeley, and other higher education and Research institutions, to examine the scientific importance of an EIC, as well as the international implications of building an EIC in the United States.
As one of the 15 members on the committee, Gao worked on this study for more than a year and contributed to the final report, especially with regard to the three-dimensional structure of the nucleon and the international context of U.S. JLab-12, China EicC planning and the Hadron Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC).
Gao noted that there are two frontiers in nuclear and particle physics, namely the high-energy frontier and the intensity frontier. The former aims at producing ever greater energy while the latter seeks to attain ever greater precision. The two approaches are complementary and both should be pursued vigorously, she said.
“Science is all about discovery and sometimes a null result can itself be a discovery,” she said. “The pursuit of either the intensity or high-energy frontier often leads to technological breakthroughs and innovations which can be applied to benefit society at large.”
According to the report, the proposed EIC would allow scientists to investigate where the tiny particles quarks and gluons are distributed inside protons and neutrons, how they move, and how they interact together.
Crucial questions that an EIC would answer include the origin of the mass of proton, the origin of spin of neutrons and protons – a fundamental property that makes magnetic resonance imaging (MRI) possible, how gluons hold nuclei together, and whether emergent forms of matter made of dense gluons exist.
The EIC would be the most advanced particle collider of its type ever built. Possible plans for electron-ion colliders are also under discussion in China and Europe, but none of them is at as advanced a stage, and will fully address the same scientific questions as the one proposed for construction in the United States and considered by the US National Academy Panel.
Along with advancing nuclear science, the report said that an EIC would also benefit other areas of scientific research such as astrophysics, as well as accelerator physics, and theoretical and computational modeling. Moreover, it would have a significant role in advancing the technologies that would result from the construction and operating of an EIC.
“It would be significant for the U.S. for many reasons, including scientific discovery, technological innovation, and talent cultivation,” Gao said.
Different from other scientific fields that flourish in multiple research institutes worldwide, the development of high-energy nuclear and particle physics depends on large-scale scientific facilities.
In the past decades, Europe, the United States, China and Japan have built their own colliders. Even though colliding objects, or center-of-mass energies are different, they all contribute to exploring the fundamental structure of matter, deepen our understanding of the universe and could potentially power the technologies of tomorrow.
As an example, the Large Hadron Collider (LHC), the world's largest and most powerful particle collider, was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008. By colliding protons and reconstruction of final-state particles, CERN announced the discovery of the long sought-after Higgs boson - the so-called God particle – responsible for why elementary particles have mass in 2012. The discovery led to a Nobel Prize a year later.
Inspired by the CERN’s success in confirming the existence of the Higgs boson, physicists from China, Japan and Europe have proposed their own next-generation colliders.
The Chinese Academy of Sciences’ Institute of High Energy Physics, the driving force behind China’s collider project, completed the initial conceptual design for a super-giant particle collider in June, 2016 and will wait until 2020 for the chance to land a significant injection of State funds.