James S. McDonnell Distinguished Professor of Physics, Emeritus
Val L. Fitch, who spent all his professional life in Princeton, died in Princeton NJ February 2, 2015, one month shy of his 92nd birthday. He was born in Nebraska on March 10, 1923 on a cattle ranch about 40 miles southeast of Wounded Knee, that his father, Fred Fitch, had acquired just 20 years after the massacre. As Val wrote, “The Sioux were very much a part of our environment, and my father, while not fluent spoke their language. They recognized his friendly interest on their behalf by making him an honorary chief, naming him ‘Eagle Star.’ The sheer physical labor for my parents was immense -- it has been observed that ranching is hell for women and horses.” Soon after Val’s birth the family moved to nearby Gordon, where Val loved to work in his basement “laboratory,” with a separate fuse box to prevent blackouts in the rest of the house. Graduating from Gordon HS in 1940 as valedictorian, he followed his older siblings to Chadron State College until drafted in March 1943.
During his basic training Val was selected for the Army Specialized Training program (AST) at Carnegie Tech, and then for the Manhattan Project as the only recruit chosen out of 1,200. He was sent to Los Alamos, where he observed that “the most accomplished experimentalists were also the ones who knew most about electronics, and electronic techniques were the first I learned. But mainly I learned not just to consider using existing apparatus but to allow the mind to wander freely and invent new ways of doing the job.” Given responsibilities far beyond his formal status, under British physicist Ernest Titterton’s supervision Val designed and built the apparatus to trigger the detonation of the first bomb on July 16, 1945 at Alamogordo, New Mexico. After the explosion he encountered a guard who had not been told what to expect: “He was absolutely pale and a look of incredible alarm was on his face. I simply said what was on my mind, ‘The war will soon be over.’ ”
At Titterton’s suggestion, Val studied electrical engineering at McGill University, graduating in 1948. He entered Columbia University to work with James Rainwater, who handed him a paper by Princeton’s John Wheeler on determining nuclear radii via X rays from captured muons, and said it might make a good thesis topic. Val “took it and ran,” building scintillation counters, trigger circuits, sodium iodide photon detectors, and a pioneering multichannel analyzer. “Every piece of electronics was home-designed and constructed. Nothing was available commercially.” The results were auspicious. Wheeler had calculated for lead that nuclei X-rays would peak at 4.5 MeV, but instead Val and Rainwater found a peak at 6.02 MeV – implying that nuclei were about twice as dense and far smaller than previously measured. In May 1953 Val and Rainwater shared the front page of the NY Times with Hillary’s ascent of Everest, the issue of Newsweek with Elizabeth II’s coronation, and won a pithy headline in the NY Daily News: “A Bad Day for Fission, the Nucleus is Just a Shrimp.”
Recruited by Wheeler to Princeton in 1954, Val embarked on a pioneering series of experiments in the burgeoning field of high energy physics – in particular the weak interactions and the marvelously rich physics of the K mesons. At that time it was thought that all the laws of physics are the same under three discrete symmetry transformations: reversal of charges (charge conjugation C), reﬂection of spatial coordinates (parity transformation P) and/or time inversion (T). Furthermore, the fundamental symmetry of nature, expressed by the CPT theorem, requires all of the laws of physics to be the same under simultaneous C, P, and T transformations.
Using the new Brookhaven Cosmotron, Val found that two “K-meson-like” charged particles of same mass, but opposite parity (P) as evidenced by their different decays, had lifetimes equal within a few percent. This measurement motivated the historic proposal in 1956 by Lee and Yang of the Institute for Advanced Study that parity (P) was not conserved in weak interactions.
His key innovation, the velocity-selecting Cherenkov counter, cleanly separated Kmesons from protons and pions in the beam. Appropriately named the Fitch counter, it has been a workhorse ever since.
Val next turned to the neutral K mesons, in particular two neutral particle components, K1 and K2, having the same mass but opposite Charge-Parity (CP), as evidenced by their different allowed decay modes and lifetimes. The short-lived component K1 would quickly decay into two pions, leaving a “pure” K2 beam in which 2 pion decays were forbidden if CP is conserved. In 1958, one of us (James Cronin) joined Princeton and was conducting a Cosmotron experiment with a spectrometer based on optical spark chambers, which had order-of-magnitude better mass resolution than previous detectors. I n spring 1963 V al suggested to Cronin that they move his apparatus to the more powerful Alternating Gradie n t Syn c hrotron( A GS) to search for the forbidden decay of K2 into 2 pions. By July the experiment was already running, and by Christmas Fitch, Cronin, postdoc Ren é T url a y and graduate student James Christenson had found 45 10 K2 candidate events decaying into 2 pions . E ffortstofindotherexplanations were unsuccessful, establishing the discovery of CP violation and creating a sensation.
The CPT theorem requires that CP violation must be accompanied by a violation under the reversal of time (T). Subsequent experiments have confirmed this. The CP discovery alsohad consequences extending b e y ondparticlep h ysics, leading Andrei Sakharov to pose a scenario in 1967 that could explain the evolution from the Big Bang to a matter-dominated universe, a profound question unanswered to this day. (A much larger CPviolation is required for thise than the phenomenon discovered in1964.) For their work on CP and time reversal V al and Croninrec e i v edthe 1980 No b elPrize in Physics. Cronin reflects: “It was Val who suggested the use of my apparatus which made the discovery. I do not think I would ever have thought of this application. But it was good fortune that a suitable apparatus existed to reduce significantly the limit on K 2 decaying to two pions.”
Val left the study of K mesons in 1972, going first to Fermilab to search for C violation in proton-antiproton interactions, then to a cliff in Montana to search for short-distance gravitational forces. Though no signals were found, each case displayed Val’s technical creativity and trained outstanding students.
Val was often called upon for major service: Member of the President’s Science Advisory Committee from 1970 to 1973; chair of the Princeton physics department from 1976 to 1981; President of the American Physical Society in 1988 and 1989 – the only person since 1932 to serve two years. As physics chair, Val sent a budget request to the president that included a comment that is now legendary: “President Bowen, you can’t buy the world’s best physics department, but you have to pay for it,” recruited a remarkable set of new faculty, and even shoveled snow from the walk to make sure the staff would be safe in coming in to work.
When an APS panel came under vicious personal attack for a report criticizing the Strategic Defense Initiative (Star Wars), Val rose to the defense, dismissing the attackers’ technical claims as “errors in physics … extravagant assumptions … unproven technologies,” and their ad-hominem diatribes as “… a bizarre attack with no place in technical discussion.” Val and the report were completely vindicated.
Val was in the last “class” of professors who had to retire at age 70. The university would have made an exception for him if necessary, but for obvious reasons asked him to consider instead an appointment as “Lecturer with Rank of Professor.” Val graciously accepted, and continued in this role for 3 years. Retirement in 1993 didn’t stop Val’s work: He led an AGS experiment searching for 6-quark states, organized a major conference on Princeton’s 250th anniversary, and wrote historical articles on particle physics.
Val’s influence on physics was enormous: as a developer of experimental technique (for example, he was the first to use transistors in high energy experiments), as a researcher with his eye on the physics, and as a teacher and mentor to generations of students and colleagues. A member of the National Academy of Science and the American Philosophical Society, Val received numerous national honors, including the National Medal of Science, the Franklin Medal and the Lawrence Award. He was modest, self-effacing and true to his principles throughout his remarkable life. When asked why he is so reluctant to talk about himself, Val replied: “My mother always told me that if you do anything worth praise, let others praise you, don’t praise yourself.” To close friends and colleagues this “says it all.”
Val’s first wife Elise Cunningham, with whom he had sons John (deceased in 1987) and Alan, died in 1972. Quoting from his Lawrence acceptance speech in 1968: “Finally, …one doesn’t do significant explorations without a superb base camp – a comforting retreat. My wife, Elise, shares this honor in every respect.” In 1976 he married journalist Daisy Harper, who survives him. In their 39 years together Val and Daisy enjoyed warm connections with families and friends in the Princeton community and around the world, and looked forward to relaxing summers in Smith’s Cove, Nova Scotia.
We shall never forget Val Fitch, by any measure a most exceptional scientist and human being!
James W. Cronin Pierre A. Pirou é A. J. Stewart Smith
Mr. President: for the Committee I move that this Resolution be spread on the records of the Faculty; that a copy be sent to his wife, Daisy Fitch, his son Alan Fitch, and to the Archivist of the University.