Seth Neddermeyer

Seth Henry Neddermeyer was born in Richmond, Michigan, on September 16, 1907. He attended Olivet College, a small college that his mother, older sister, and uncle had also attended, for two years before his family moved to California. He transferred to Stanford University, from which received his Bachelor of Arts (AB) degree in 1929. under the supervision of Carl D. Anderson. He confirmed the theory espoused by Niels Bohr for this process. He also noted large radiative energy losses of electrons in lead, in agreement with the theory propounded by Hans Bethe and Walter Heitler. That year, Neddermeyer and Anderson discovered the muon, using cloud chamber measurements of cosmic rays. Their discovery predated Hideki Yukawa's 1935 theory of mesons that postulated the particle as mediating the nuclear force. Anderson and Neddermeyer collaborated with Millikan in high altitude studies of cosmic rays, which confirmed Robert Oppenheimer's theory that the air showers produced in the atmosphere by cosmic rays contained electrons. They also obtained the first evidence that gamma rays can generate positrons. ==Manhattan Project work==

In early 1941, with World War II raging in Europe but the United States not yet a belligerent, Neddermeyer joined a team led by Charles C. Lauritsen and William A. Fowler at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, and then at the National Bureau of Standards in Washington, D.C., that worked on the photoelectric proximity fuze. Although implosion was suggested by Richard Tolman as early as 1942 and discussed in the introductory lectures given to Los Alamos scientists by Robert Serber, Neddermeyer was one of the first to urge its full development. ==Later years==

In 1946, after World War II ended, Neddermeyer left Los Alamos to become an associate professor at the University of Washington, where he would spend the rest of his career. In due course he became a full professor. He resumed his studies of cosmic rays using a cloud chamber and a new device that he invented to measure the speed of charged particles known as a "chronotron". He was particularly interested in the properties of the muon, and conducted experiments with muons at SLAC. He participated in the DUMAND Project, for which he helped design large-scale underwater neutrino detectors. ==In popular culture==

Neddermeyer is portrayed by Colin Bennett in the 1980 BBC series Oppenheimer, by Joe D'Angerio in Fat Man and Little Boy, and by Devon Bostick in the Christopher Nolan-directed film Oppenheimer (2023). ==Notes==