James W. Cronin, Nobel laureate and pioneering physicist, 1931-2016

James W. Cronin, a pioneering scientist who shared the Nobel Prize in physics in 1980 for his groundbreaking work on the laws governing matter and antimatter and their role in the universe, died Aug. 25 in Saint Paul, Minn. He was 84.

Cronin, SM’53, PhD’55, spent much of his career at the University of Chicago, first as a student and then a professor. A University Professor Emeritus of Physics and Astronomy & Astrophysics, he was remembered this week as a mentor, collaborator and visionary.

“He inspired us all to reach further into the unknown with deep intuition, solid scientific backing and poetic vision,” said Angela Olinto, the Homer J. Livingston Distinguished Service Professor in Astronomy and Astrophysics. “He accepted his many recognitions and accolades with so much humility that he encouraged many generations to follow his vision.”

Edward “Rocky” Kolb, dean of the Physical Sciences Division and the Arthur Holly Compton Distinguished Service Professor in Astronomy and Astrophysics, described Cronin as “a person of real honesty and integrity who was a mentor and friend to so many people.”

“Just like in basketball, there are good players in science, but the greatest players are the ones who make the people around them better. Jim was that great player,” Kolb said.

Cronin’s research that resulted in the Nobel Prize came in 1964 while he was working with Val Fitch at the Brookhaven National Laboratory. The two scientists, who were Princeton University professors at the time, observed the first example of nature’s preference for matter over antimatter. Without the phenomenon, which physicists refer to as charge-parity violation, no matter would exist in the universe.

Cronin and Fitch studied the short-lived subatomic particles that appeared after the collision of accelerated protons and the nucleus of an atom. They observed indirect charge-parity violation, which is the unbalanced mixing of neutral subatomic kaon particles with their charged antiparticles. Called the Fitch-Cronin effect, the finding showed that some physical laws are violated when the direction of time is reversed. It also lent support for the big bang theory of the universe’s origin.

Cronin later in his career shifted his focus, becoming co-leader of the Pierre Auger Project. The $50 million international collaboration of 250 scientists across 16 nations focused on the mysterious sources of rare but extremely powerful cosmic rays that periodically bombard Earth. The project led to the creation of the Auger Observatory, which consists of a vast array of cosmic-ray detectors in Argentina.

“It was 25 years ago since Jim and I first conceived the idea of what became the Auger Collaboration. It was definitely a great partnership as we drummed up financial and scientific support for the collaboration,” said Alan Watson, emeritus professor of physics at the University of Leeds and a fellow of the Royal Society.

The collaboration has made definitive measurements on the energy spectrum of cosmic rays, on the patterns of their arrival directions, and on their mass compositions. It also has conducted particle physics research, measuring phenomena that far exceed the energies of the Large Hadron Collider.

“It’s been an outstanding success, and it’s still going strong,” Watson said.

Drawing inspiration from Fermi

Cronin was born on Sept. 29, 1931, in Chicago, while his father was a graduate student in classical languages and literatures at the University of Chicago. The younger Cronin received a bachelor’s from Southern Methodist University in 1951 before returning to the University of Chicago as a National Science Foundation Fellow to earn his master’s and doctoral degrees.

Cronin met his first wife, Annette Martin, while both were students at the University. She died in 2005, and Cronin married Carol McDonald (nee Champlin) in late 2006.

Cronin began his scientific career at Brookhaven before becoming a member of the physics faculty at Princeton in 1958. In 1971, he joined the University of Chicago, where he was appointed the University Professor of Physics. He became University Professor Emeritus of Physics and Astronomy & Astrophysics in 1997.

Cronin shared a birthdate with Prof. Enrico Fermi, who earned the Nobel Prize in Physics in 1938. Cronin, who knew Fermi from his graduate school days at UChicago, organized a symposium in 2001 to mark the 100th anniversary of Fermi’s birth, and was editor of the resulting book, Fermi Remembered. It included contributions from seven Nobel Prize recipients and many other scientists who studied under or worked with Fermi at UChicago.

“What’s significant about Fermi is if you look through his career, he never just did the same thing. He kept moving on to new scientific challenges,” Cronin once said of Fermi. The same statement also could be applied to Cronin and his research shift from high-energy physics to ultra-high-energy cosmic rays.

Cronin’s honors include the University of Chicago Alumni Medal (2013), an honorary doctoral degree from the Karlsruhe Institute of Technology in Germany (2013), election as a foreign member of the Royal Society of London (2007), Distinguished Graduate Award of SMU’s Dedman College (2004), Legion d’honneur of France (2001), National Medal of Science (1999), University of Chicago’s Quantrell Award for Excellence in Undergraduate Teaching (1994), Laureate of Lincoln Academy of Illinois (1981), Ernest Lawrence Memorial Award for outstanding contributions in the field of atomic energy (1977), John Price Wetherill Medal of the Franklin Institute (1975) and the Research Corporation Award (1968).

In 1990 Cronin delivered the Ryerson Lecture, which provides an opportunity each year for a distinguished faculty member to address the UChicago community on significant aspects of his or her research.

He was a member of the National Academy of Sciences, American Academy of Arts and Sciences, American Physical Society, American Philosophical Society, Accademia Nazionale dei Lincei of Italy, Mexican Academy of Sciences and the Russian Academy of Sciences. Cronin also had received honorary doctorates from l’Université Pierre et Marie Curie, University of Leeds, Université de Franche Conte, Novo Gorica Polytechnique of Slovenia, University of Nebraska and the University of Santiago de Compostela and the Colorado School of Mines. Cronin served as international chair of the College de France in 1999-2000.

Cronin is survived by his wife, Carol; daughter, Emily Grothe; son, Daniel Cronin; and six grandchildren: James, Cathryn, Caroline, Meredith, Alex and Marlo. A daughter, Cathryn Cranston, died in 2011.

Arrangements for a memorial service are pending.