In a groundbreaking event in physics in 1974, American physicist Burton Richter found the particle that confirmed the existence of what was known as the charm quark. It was the missing piece needed to adopt a new theory of the structure and composition of matter at its most fundamental level. (Department of Energy)

Burton Richter, an American physicist who shared the 1976 Nobel Prize for discovering a subatomic particle, the curiously named “charm quark,” that became a foundation stone of the modern understanding of matter at its deepest levels, died July 18 in Palo Alto, Calif. He was 87.

His death was announced by Stanford University, where he was a longtime professor. Other details were not immediately available.

In addition to serving as director of a major Department of Energy laboratory, Dr. Richter also became known in his later years for other contributions to academic and public life. Along with exerting influence in government on science matters, he published a book on climate change.

At Stanford, by first designing and financing, then building and finally using a high-energy particle accelerator and an advanced particle detector, Dr. Richter made a discovery that startled science.

On Nov. 10, 1974, in a groundbreaking discovery in physics, he found the particle that confirmed the existence of what was known as the charm quark. It was the missing piece needed to adopt a new theory of the structure and composition of matter at its most fundamental level.

His discovery, and the reassessments that it prompted, became known as the “November Revolution,” recalling the “October Revolution” in Russia that changed 20th-century history.

Dr. Richter receives the Nobel Prize from the king of Sweden in 1976 for his co-discovery. (Nobel Foundation/Courtesy of the SLAC National Accelerator Laboratory, Archives and History Office)

At the same time that Dr. Richter made his breakthrough, physicist Samuel C.C. Ting of the Massachusetts Institute of Technology made a similar discovery. Dr. Richter called his particle, known to physicists as a meson, by the Greek letter “psi”; Ting’s particle was dubbed “J.” Together, they were known as the J/psi meson.

“The suddenness of the discovery coupled with the totally unexpected properties of the particle are what make it so exciting,” Dr. Richter and Dr. Ting jointly wrote in 1974. “It is not like the particles we know and must have some new kinds of structure.”

Each scientist had found the first experimental traces of a sort of physicist’s grail: the eagerly sought charm quark. In particular, they had found a particle composed of a charm quark bound together with an anticharm quark.

“It’s something that everybody hopes they’re going to do,” Dr. Richter later said, “and I was a lucky one because it happened.”

Dr. Richter and Dr. Ting shared the 1976 Nobel Prize for Physics.

“It was clear from day one that J/psi was a major discovery,” physicist Tom Appelquist said in 1974. “It almost completely reoriented the theoretical community. Everyone wanted to think about it.”

Before their discovery, science had come to accept the existence of three of the “quarks” that were considered to be the underlying constituents of the particles once viewed as the basic building blocks of matter. Other scientists had proposed that a fourth quark must exist, but it was not confirmed until Dr. Richter’s and Ting’s discovery of the charm quark. It was adopted as part of the Standard Model of particle physics, describing how subatomic particles interact.

The name “quark” had no particular scientific significance. It was chosen, with a degree of whimsy from a line in James Joyce’s “Finnegans Wake”: “Three quarks for Muster Mark!” In the same way, the term “charm” in the charm quark speaks not of any particular attribute of the particle, but is one more expression of whimsy.

“What lots of people have been trying to do ever since is find what’s beyond the current Standard Model,” Dr. Richter said in 2014. “So far, it has stood impervious to all attacks.”

Burton Richter was born in New York City on March 22, 1931. His father was a textile worker; his mother, a homemaker.

Blackouts imposed early in World War II made it possible to see the Milky Way and fostered Dr. Richter’s interest in science.

He attended the private Mercersburg Academy in Pennsylvania before entering MIT. In addition to being president of the chess club, he participated in wrestling, tennis and football.

At MIT, he received a bachelor’s degree in 1952 and a doctorate in 1956. He then went to Stanford, where he became a full professor in 1967.

In 2010, Dr. Richter published “Beyond Smoke and Mirrors: Climate Change and Energy in the 21st Century,” a book seeking to explain the facts of climate change to nonscientists.

Dr. Richter directed the Department of Energy’s SLAC National Accelerator Laboratory at Stanford from 1984 to 1999. He received the nation’s highest scientific honor, the National Medal of Science, in 2014.

He was a member of the National Academy of Sciences, a fellow of the American Academy of Arts and Sciences and the American Association for the Advancement of Science, and former president of the International Union of Pure and Applied Physics and the American Physical Society. He was also a member of JASON, an independent group of scientists who advise the U.S. government.

Survivors include his wife of 58 years, the former Laurose Becker of Palo Alto; two children, Elizabeth Richter of Columbia, Md., and Matthew Richter, of Woodside, Calif.; and two granddaughters.

Lynn Carroll, a family friend, recalled being taken to meet Richter and his wife for the first time. She said they were described to her this way: “Burton knows everything about high-energy physics, and Laurose knows everything about everything else.”