Val Logsdon Fitch (March 10, 1923 – February 5, 2015) was an American nuclear physicist who, with co-researcher James Cronin, was awarded the 1980 Nobel Prize in Physics for a 1964 experiment using the Alternating Gradient Synchrotron at Brookhaven National Laboratory that proved that certain subatomic reactions do not adhere to fundamental symmetry principles.

Born on a cattle ranch near Merriman, Nebraska, Fitch was drafted into the U.S. Army during World War II, and worked on the Manhattan Project at the Los Alamos Laboratory in New Mexico.

There he met many of the greats of physics including Niels Bohr, James Chadwick, Enrico Fermi, Isidor Isaac Rabi, Bruno Rossi, Emilio Segrè, Edward Teller and Richard C. Tolman, in some cases attending physics courses taught by them.

He worked in the group headed by Ernest Titterton, a member of the British Mission, and became well-acquainted with the techniques of experimental physics.

He participated in the drop testing of mock atomic bombs that was conducted at Wendover Army Air Field and the Naval Auxiliary Air Station Salton Sea, and worked at the Trinity site, where he witnessed the Trinity nuclear test on July 16, 1945.

Robert Bacher, the head of the physics division at Los Alamos, offered him a graduate assistantship at Cornell University, but first he needed to complete his undergraduate degree.

[1][2] Fitch designed and built an experiment to measure the gamma rays emitted from mu-mesic atoms.

Columbia had recently commissioned a cyclotron at the Nevis Laboratories that could produce muons; Robert Hofstadter had developed the thallium-activated sodium iodide gamma ray detector; and wartime advances in electronics yielded advances in components such as new phototubes needed to bring it all together.

Initially nothing was found, but Rainwater suggested expanding the search beyond the energy range predicted by Wheeler on the basis of the then-accepted size of the radius of the atomic nucleus as around 1.4 × 10−15 m. When this was done, they found what they had been looking for, discovering in the process that the nucleus was closer to 1.2 × 10−15 m.[1][2] He completed his PhD in 1954, writing his thesis on "Studies of X-rays from mu-mesonic atoms".

Cronin had built a new kind of detector, a spark chamber spectrometer, and Fitch realized that it would be perfect for experiments with K mesons (now known as kaons), which Yale University physicist Robert Adair had suggested had interesting properties worth investigating.

Along with two colleagues, James Christenson and René Turlay, they set up their experiment on the Alternating Gradient Synchrotron at Brookhaven.

[10][13][14] The importance of this result was not immediately appreciated; but as evidence of the Big Bang accumulated, Andrei Sakharov realized in 1967 that it explained why the universe is largely made of matter and not antimatter.

[18][19] In 1981, Fitch became a founding member of the World Cultural Council[20] and received the Golden Plate Award of the American Academy of Achievement.