Burton Richter, a Nobel Prize–winning particle physicist who also exercised significant influence in scientific policy, died on 18 July, the laboratory announced yesterday. He was 87 years old. In 1974, Richter’s key scientific discovery laid a cornerstone for physicists’ standard model of fundamental particles and forces. In later years, he played an important role in U.S. science policy, including a restructuring of the Department of Energy that elevated its scientific efforts.
“The thing about Burt is that he never went out and said, ‘This is what I did,’” says Michael Lubell, a physicist at City College of New York and a former lobbyist with the American Physical Society (APS) in Washington, D.C. “He was content with the outcome.”
Richter won nearly instant scientific fame in 1974 when he and his team at the Stanford Linear Accelerator Center (now SLAC National Accelerator Laboratory) in Menlo Park, California, smashed together high-energy electrons and positrons to produce a new particle which they dubbed the ψ. The discovery was key because the ψ turned out to be made of a particle called the charm quark and its antimatter partner. At essentially the same time, a team at Brookhaven National Laboratory in Upton, New York, discovered the same particle, which they called the J. The particle is still called the J/ψ.
The discovery significantly expanded scientists’ understanding of particles called quarks, which had been discovered at SLAC only a few years earlier. Physicists knew that two more familiar particles—protons and neutrons—were made of trios of quarks. Two types of quarks, up quarks and down quarks, combine to make protons and neutrons. Researchers also knew of a third type, the strange quark. The discovery of the ψ confirmed a prediction of a fourth type of quark. But far more important, it clinched the case for a particular theory, known as the GIM mechanism, of how the different types of quarks come in pairs and how they interact through the so-called weak nuclear force. Until then, ideas of what quarks were and how they behaved were all over the map, says Gordon Kane, a theorist at the University of Michigan in Ann Arbor. “This is the importance of the J/ψ,” he says. “You went from n ideas, most of them half-baked, to one idea, the right one.”
The SLAC and Brookhaven results simultaneously confirmed each other. “It was a revolutionary moment, everybody was excited,” says Sheldon Glashow, a theorist at Boston University and one of the inventors of the GIM mechanism. For the J/ψ discovery, Richter and Samuel Ting of the Massachusetts Institute of Technology in Cambridge shared the Nobel Prize in Physics in 1976. Physicists now know that there are six types of quarks in three pairs that interact as the GIM mechanism predicts.
In addition to his signature discovery, Richter was renowned for his expertise in building particle accelerators. He designed the Stanford Positron-Electron Accelerator Ring (SPEAR), the collider that his team used to discover the J/ψ. Richter was also very open to ideas from other fields, says Arthur Bienenstock, a solid-state physicist retired from Stanford University in Palo Alto, California. For example, he says, Richter was open to the simultaneous use of the x-rays generated by SPEAR to do experiments in solid state physics and materials sciences. SPEAR would eventually become an x-ray source known as the Stanford Synchrotron Radiation Lightsource (SSRL), the world’s first synchrotron-radiation facility for users from the wider scientific community, which Bienenstock directed from 1978 to 1997.
In later years, Richter’s interest spread into nuclear power, energy technology, and climate change. Policymakers in Washington, D.C., took his advice seriously, Lubell says. For example, when Lubell was at APS, he and Richter urged Congress and the White House to reorganize the Department of Energy to create a separate undersecretary for science instead of having just one undersecretary for the entire department. The effort came to a head in 2005, Lubell recalls, when he and Richter went to see then–Secretary of Energy Samuel Bodman. “Bodman listened intently and said, ‘You’re right, we’re going to do it this way,’” Lubell says. In 2005 Congress passed an act that established the position.
Richter was also one of a handful of scientists who in 2008 helped the then-incoming Barack Obama administration identify $20 billion worth of “shovel-ready” research projects across scientific disciplines that it would fund from the economic stimulus package called the American Recovery and Reinvestment Act that Congress approved in 2009 to ameliorate the sudden crash of the economy.
Richter was tough, but always friendly and principled, others say. Bienenstock recalls that he and Richter regularly clashed over sharing SLAC’s signature linac to feed SSRL, which was originally an independent national laboratory, and SLAC’s particle physics experiments. But when the two labs were formally merged, in 1992, Bienenstock says, Richter was fully supportive of SSRL and the two became good friends. “He was gracious in a profound way,” Bienenstock says.
Glashow agrees. In 2016, he taught a course for a dozen freshman on energy issues and climate change and decided to assign Richter’s 2010 book Beyond Smoke and Mirrors: Climate Change and Energy in the 21st Century. When Glashow told Richter, Richter sent him 12 copies of the book, personally inscribed to each student.