About this Member
Charles Hohenberg has been a Professor of Physics at Washington University for 45 years. He received his BS in Physics from Princeton in 1962 and his PhD from the University of California, Berkeley, in 1967. He is an experimental physicist who designs and builds his own equipment, utilizing the sensitivity of noble gas mass spectrometry in a number of different fields. During the course of his research he developed new high-precision ion-counting noble gas mass
spectrometer systems, and the associated ultra-low-blank auxiliary systems, capable of measuring noble gas isotope ratios at the thousand atom level. Studying the abundances of now extinct 129 I and 244 Pu, he developed early self-consistent models for galactic nucleosynthesis. Through a large, multi-year effort, he developed 129 I into a refined I-Xe dating method suitable for delineating early Solar System evolution with a resolution of 100,000 years or less. Necessary in his work was development of pulsed and CW laser systems for the extraction of noble gases from individual micron-sized grains. The precision of I-Xe dating and laser excision allows determination of cooling rates of iron meteorites. He discovered the first hard evidence for an early active (T-Tauri) sun by observing quantities of spallation-produced 21 Ne in individual meteoritic olivine grains which contained cosmogenic 21 Ne far in excess of that due to contemporary sources of energetic particles (solar and galactic cosmic rays and secondaries). Measured decay half-lives by the accumulation of heavy noble gas daughter products, including the longest half-life ever experimentally measured (8.0 x 10 24 years for 128 Te, measured in 2 billion year old native Te). He refined the 81 Kr-Kr exposure age dating method and established the ages of many prominent lunar features (Tyco, North Ray crater and South Ray crater to precisions of a few percent), and studied meteorite exposure ages and lunar surface dynamics by the same method. He investigated the ancient natural spontaneous chain reactions in old uranium deposits Oklo (Gabon), a natural reactor) deposits. Recent work for the Stardust Mission led to the documentation of “anomalous adsorption” of heavy noble gases, a new mechanism for incorporation of heavy noble gases onto 2-D surfaces involving chemical rather than Van der Waals bonds. As a member of the Genesis and Stardust mission science teams, much recent activity has been in construction of multiple multiplier noble gas mass spectrometers in house, and collaborative design efforts with two commercial manufacturers: Nu-Instruments and GV Instruments. Results from the Genesis Mission has led to the highest precision determination of Kr and Xe isotope ratios in the solar wind, by inference the Sun, the starting composition of the solar system. He has been fully supported by NASA for all of his research activities.
Dr. Hohenberg remained at Berkeley for two and a half years after receiving his PhD in 1967 to study the Apollo 11 samples. He then joined the Washington University Physics Department as an Assistant Professor in 1970, becoming Full Professor in 1978, where he was an active researcher for all Apollo Missions. However, he but spent much of his time studying noble gases in meteorites, the best preserved samples of the early solar system, where I-Xe dating has helped understand its early evolution. He has published approximately 320 reviewed publications, produced a dozen PhD physicists many are actively pursuing their own exciting work (5 university faculty, 4 national laboratories).
Dr. Hohenberg is married to Victoria Marshall Hohenberg, the father of 4 children, and lives in St. Louis Missouri.