Burton Richter

From Far Rockaway to MIT

Burton Richter was born in Brooklyn, New York, on March 22, 1931, the elder child of Abraham Richter, a textile worker, and Fanny Richter, née Pollack. His family was Jewish, and he grew up in Far Rockaway, Queens, by the Atlantic shore. He went to Far Rockaway High School and then Mercersburg Academy in Pennsylvania.

In 1948 he entered the Massachusetts Institute of Technology, unsure whether to study chemistry or physics. His first year settled it in favour of physics, thanks in part to teachers like Francis Friedman, who opened his eyes to its beauty, and Francis Bitter, who gave him his first chance at serious experiments in MIT’s magnet laboratory. There he also had his first taste of the physics of electrons and positrons, working part-time on Martin Deutsch’s classic experiments on positronium.

Learning to build machines

As a graduate student at MIT from 1952, Richter made a short-lived isotope of mercury by bombarding gold in the MIT cyclotron, which he called a kind of reverse alchemy. He found himself more interested in the accelerator than in the experiment, spent six months at Brookhaven National Laboratory’s new proton accelerator to test his interest, and returned to do his doctorate at the MIT synchrotron, a small machine where students had to design their own apparatus and help maintain the accelerator. He received his PhD in 1956.

He then moved to Stanford’s High-Energy Physics Laboratory, where his first experiment showed that the theory of quantum electrodynamics held at distances as small as about a ten-trillionth of a centimetre. To probe even smaller distances, in 1957 he joined Gerard O’Neill of Princeton and two colleagues to build one of the first colliding-beam machines, in which two beams of particles circulate in storage rings and smash head-on. It took six years to make the beams behave. That device, he wrote, was the ancestor of all the colliding-beam storage rings that followed, and the technique became so productive that almost every high-energy accelerator since has been a collider.

When the Stanford-Princeton machine finally worked, in 1965, the experiment extended the validity of quantum electrodynamics to distances smaller than a hundred-trillionth of a centimetre. Even before it was running, Richter had begun to imagine a much more powerful electron-positron collider. Robert Hofstadter had mapped the structure of the proton by scattering electrons off it, and Richter realised that colliding beams of electrons and positrons could give a similar picture of short-lived particles that could never be made into a target.

SPEAR and the November Revolution

In 1963 Wolfgang Panofsky invited Richter to the new Stanford Linear Accelerator Center, SLAC, where he set up a group to design a high-energy electron-positron collider. Funding took years of struggle. Money finally came in 1970, and with David Ritson he built the Stanford Positron Electron Asymmetric Rings, SPEAR, together with a large magnetic detector. Experiments began in 1973.

In November 1974 Richter’s team saw a sharp, unexpected spike in the rate of collisions at a single energy, about 3.1 billion electron volts, the signature of a new and surprisingly long-lived particle. He named it psi. At the same moment, Samuel Ting’s team at Brookhaven found the same particle and called it J, and the two discoveries were announced together. The J/psi turned out to be made of a new kind of quark, the charm quark, and its partner antiquark.

The discovery forced a rapid rethinking of theory and became known as the November Revolution. It convinced physicists that quarks were real, physical objects rather than a bookkeeping device, and it confirmed key predictions of what became the Standard Model of particle physics. Richter and Ting shared the Nobel Prize in Physics in 1976.

Opening the door to X-ray science

One of Richter’s most far-reaching decisions had nothing to do with quarks. While SPEAR was being built, two Stanford professors, Sebastian Doniach and William Spicer, came to him with a proposal. Electrons racing around a storage ring give off intense X-rays, a nuisance to particle physicists, but those X-rays could be a million times brighter than anything an X-ray tube could produce. They wanted a port in the ring to let the beam out for experiments on materials.

Richter agreed and spent the extra money to cut the port. As he later wrote, the world was simpler then, and he just did it. The result was the first of the modern synchrotron radiation facilities, the Stanford Synchrotron Radiation Lightsource, and it became the prototype for many others around the world. Today SPEAR is dedicated entirely to X-ray science and serves about two thousand academic and industrial scientists, working on problems from drug design and environmental clean-up to electronics and medical imaging.

Leading SLAC

After a sabbatical at CERN in 1975 and 1976, during which he worked out the scaling laws for electron-positron storage rings and produced a first design for CERN’s 27-kilometre LEP collider, Richter turned to a new kind of machine, the linear collider, in which beams from straight accelerators are focused to a tiny spot and fired at each other. He led the conversion of SLAC’s two-mile accelerator into the SLAC Linear Collider, built from 1983 to 1987, the first machine of its kind.

He served as SLAC’s technical director from 1982 and as director from 1984 to 1999. Under his leadership the synchrotron radiation programme became part of the laboratory, work began on an X-ray free-electron laser based on linear collider technology, and SLAC moved into astrophysics through the GLAST gamma-ray space telescope. He insisted that a laboratory must keep renewing itself, warning that starving the future to feed the present leads to stagnation. He was also president of the American Physical Society in 1994.

A machine for the whole world

The insight behind the linear collider came from Richter’s work at CERN. He showed that the size and cost of circular electron colliders grow with the square of their energy, so a machine ten times more powerful than LEP would be unaffordable. At a 1978 workshop he discovered that Alexander Skrinsky of Novosibirsk and Maury Tigner of Cornell had been thinking along the same lines, and together with others present they derived the key equations for designing linear colliders. In the SLAC Linear Collider the beams had to be squeezed to a radius of no more than two microns at the collision point, about a thousand times smaller in area than in a storage ring. By the time it was switched off, it was colliding beams twenty times smaller in area than its design.

Richter believed that the next great collider should be built by the whole world rather than by one region. In the late 1970s he and Guy von Dardel tried, without success, to turn LEP into an inter-regional project. Later, with Bjørn Wiik of Germany’s DESY laboratory and Hirotaka Sugawara of Japan’s KEK, he started a collaboration aimed at a global linear collider, an idea that by 2005 had become a consensus among particle physicists. He was also a member of the JASON group of scientists who advise the U.S. government, and in 2008 he joined other scientists in urging emergency funding for American research.

Energy and climate

After stepping down as director, Richter devoted more and more of his time to energy, the environment and sustainability. Meeting the energy needs of the developing world without causing an ecological disaster, he wrote, would require a marriage of science and technology with good international policy. He wrote Beyond Smoke and Mirrors: Climate Change and Energy in the 21st Century, published in 2010, to explain the science and the policy choices to general readers.

He served on many advisory bodies, including as a senior fellow of the California Council on Science and Technology from 1999, where he was a leading member of a team that studied how California could meet its goals for cutting greenhouse gas emissions by 2050, and lead author of its report on nuclear power. He was a strong advocate of nuclear energy as a low-carbon source and criticised Germany’s decision to shut its reactors. His National Medal of Science, awarded for 2012, honoured both his pioneering work on electron accelerators and his contributions to energy policy, and in 2012 he shared the Enrico Fermi Award.

Jewish roots and family

Richter grew up in a Jewish working-class family in New York, the son of a textile worker, one of many children of that world who reached the top of American science through public schools and scholarships. He did not write publicly about religious practice, and his own autobiography focuses on his work. The Jewish Virtual Library lists him among Jewish Nobel laureates in physics.

In 1960 he married Laurose Becker; they had two children, Elizabeth, born in 1961, and Matthew, born in 1963. Colleagues described him as forceful, driven and visionary; SLAC’s later director Chi-Chang Kao noted that he was unusual in being both a particle physicist and an accelerator physicist.

Legacy

Burton Richter died at Stanford on July 18, 2018, at the age of 87. His legacy is threefold. As a physicist he helped prove that quarks are real and gave the Standard Model one of its pillars. As a builder he helped invent the colliding-beam technique on which modern particle physics depends and pioneered the linear collider. And by opening a hole in his collider for X-rays, he helped create the synchrotron light sources that thousands of biologists, chemists, engineers and medical researchers now rely on, while in his final decades he used his authority to urge the world toward cleaner energy.

Sources & further reading

Burton Richter, Biographical, NobelPrize.org · Burton Richter, Wikipedia · Nobel laureate Burton Richter dies, Physics World · CCST Senior Fellow Burton Richter, Nobel Laureate, Dies, California Council on Science and Technology · Stanford Synchrotron Radiation Lightsource, Wikipedia · Burton Richter, Jewish Virtual Library · Researched from the sources above and checked against them. Spotted an error? Tell us.

A life of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.