Jesse DuMond

DuMond was born in France as a US citizen. He studied at Caltech, earning his bachelor's degree in 1916 with the construction of a calculating machine, a "harmonic analyzer". For his master's thesis he built a calculating machine for complex numbers. During World War I, he was employed (1917–1918) at General Electric as an electrical engineer, working on determining the distance of artillery via sound. In 1919–1920 he was at the Thomson-Houston Company in Paris, and 1920–21 at the National Bureau of Standards, where he worked on ballistics. Returning to graduate school at the California Institute of Technology, he in 1929 received his doctorate in physics. He spent the rest of his career at Caltech, originally at the invitation of Robert Millikan. From 1938 he was an Associate Professor and from 1946, a Professor. He retired in 1963.

DuMond became a Fellow of the American Physical Society in 1931. He was elected to the National Academy of Sciences in 1953.

Starting with his Ph.D. dissertation, DuMond became famous for investigating the line broadening in the Compton effect due to the speed distribution of the electrons in the atom. To this end, he developed a new type of X-ray spectrometer with several crystals and also had the original idea for X-ray spectrometers with curved crystal surfaces. Characteristically, he built his measuring equipment himself, often demonstrating great mechanical skill. Later he dealt with the precise determination of fundamental physical constants, such as Planck's constant and the electron charge. He found a discrepancy in the value of the electron charge between the value that Millikan had measured with his oil drop experiment and the value from X-ray diffraction experiments. Millikan then checked his old experiment and corrected its result. (The viscosity of the air affected the answer. Millikan assigned a student to measure it.) With E. Richard Cohen, DuMond published regular review reports on the status of the determination of the fundamental physical constants. DuMond also developed a gamma-ray spectrometer, finished only after World War II, with which he then pursued nuclear spectroscopy.

During the Second World War DuMond worked on rocket technology, the construction of an aerial camera, and the demagnetization of ships as a measure against magnetic mines.

DuMond was married twice and had three children from his first marriage. One daughter married Wolfgang Panofsky, who was DuMond's Ph.D. student.

• Jesse W. M. DuMond, The Autobiography of a Physicist: Volumes I, II and appendix, 1972.
• Biographical Memoirs of the National Academy of Sciences, Jesse DuMond
• American Institute of Physics, Jesse DuMond: Biography