August Carl Helmholz died of complications from pneumonia on 29 October 2003 at his home in Lafayette, California. Carl was a distinguished member of the University of California, Berkeley, physics community for more than 65 years.
Born on 24 May 1915 in Evanston, Illinois, Carl spent most of his early years in Rochester, Minnesota. He received his AB in physics from Harvard University in 1936. After a year of study at the Cavendish Laboratory, he began graduate studies at Berkeley and earned his PhD in 1940 under Edwin M. McMillan with a thesis entitled “The Energy and Spin Change in Nuclear Gamma Ray Transitions.”
From 1940 to 1946, Carl was an instructor and then an assistant professor in the Berkeley physics department and a physicist on the Manhattan Project. He became associate professor of physics in 1948 and professor in 1951. He served in a number of administrative positions, the most important of which was as chair of the physics department from 1955 to 1962.
Carl’s work on the Manhattan Project during World War II was in the magnetic separation of uranium isotopes. His PhD research in nuclear physics dealt with possible ways to determine the multipole order of various isomeric transitions. After the war, he continued his study of nuclear states produced by the bombardment of beams from Radiation Laboratory accelerators. That work culminated in 1949 with the publication, with Emilio Segrè, of what at the time was a definitive review of nuclear isomerism.
As with many of the nuclear physicists of the time, his interests naturally migrated to high-energy particle physics. While he continued isotope studies on the Berkeley campus, he worked with McMillan on the design and construction of the Berkeley 350-MeV electron synchrotron. A number of Berkeley students and visiting physicists used that accelerator to study both the production and properties of pions and muons. That effort, which was complementary to the work on the 184-inch cyclotron, was the beginning of accelerator-based research in particle physics. As accelerator energies increased, Carl turned his attention, with Berkeley colleague Burton J. Moyer, to the study of the pion–nucleon interaction. Results from their measurements were among the first signals of resonant behavior arising from the subatomic forces.
Carl was an excellent and popular classroom teacher; the names of his 54 PhD students read like a who’s who of the physicists of the last half of the 20th century. Students found his lectures to be extremely well organized and presented clearly and with humor. He was a very humane man and showed great respect for his students, who did not feel intimidated by him. Carl’s greatest scientific impact may well have been through the large number of his students who became distinguished researchers in their own right and then trained yet new generations of scientists. Carl also participated on numerous national committees dealing with education. With Moyer, he revised volume 1 of the Berkeley physics course.
Some of Carl’s most important contributions came during his chairmanship of Berkeley’s physics department. He succeeded Raymond T. Birge, who had held the post for 23 years. Given that Carl had been promoted to professor just four years earlier, the chairmanship was a challenging responsibility, especially because his distinguished predecessor continued to occupy an office adjacent to the chairman’s. Carl’s success over his seven years as chairman provides striking testimony to his diplomatic and administrative ability. The department grew from about 30 to 50 tenured faculty; the expansion was fueled by the rapid development of particle physics and the interest in space exploration. Not only in particle physics but in other emerging fields did many outstanding young physicists find a home among the Berkeley faculty. Carl deserves much credit for that.
Carl’s service to Berkeley also extended outside the physics department. He chaired many academic senate committees. After his retirement in 1980, he continued service on numerous committees of the senate and was a very active member of the committee on emeriti relations.
Carl will long be remembered at Berkeley and in the community of physicists for his scientific accomplishments, the enormous number of first-rate researchers who received PhDs under his supervision, and his superb contributions to the administrative affairs of the Berkeley campus. On a more personal level, we shall remember the kindness, generosity, hospitality, and warmth that Carl and his wife, Betty, unfailingly demonstrated throughout the years.
