Hugh C. Paxton

Hugh Campbell Paxton (April 29, 1909 – December 25, 2003) was an American nuclear physicist and a pioneer in the field of nuclear criticality safety. A doctoral student of Nobel laureate Ernest Lawrence, Paxton's early work on the energy spectra of radioisotopes provided the technical foundation for the early medical applications of the cyclotron. He spent nearly 30 years as the leader of the Critical Assemblies Group at Los Alamos National Laboratory (LANL), where he became a leading authority on fast critical experiments.

Early life and education Paxton was born in Los Angeles on April 29, 1909, His younger brother Norman L. Paxton was a naval aviator and recipient of the Navy Cross. After working at Bell Telephone Laboratories, he completed his PhD at the University of California, Berkeley in 1937.

His dissertation, The Beta-ray Spectrum of P, provided the first precise measurements of the energy distribution of electrons emitted by radioactive Phosphorus-32. Shortly after graduation, he married Jean Nellis Thomson.

Career Manhattan Project In 1941, Paxton co-authored the textbook Matter, Energy and Radiation with John R. Dunning. During World War II, he conducted cyclotron research at the Collège de France in Paris until the German occupation. He subsequently supported the Manhattan Project at Columbia University, Oak Ridge, Tennessee, and Philadelphia.

Los Alamos National Laboratory Paxton joined the Los Alamos Scientific Laboratory in late 1948, serving as leader of the Critical Assemblies Group at the Pajarito Site (TA-18) until 1975. His work involved the experimental determination of critical mass for nuclear weapons and reactors. He oversaw the operation of the **Topsy**, **Lady Godiva**, and **Jezebel** assemblies.

Selected publications