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Washington University in St. Louis News & Information > Faculty Experts at Washington University in St. Louis >
Research professor of physics in Arts & Sciences
Expertise: Geochemistry, Geochronology, Nuclear Chemistry, Xenon, Krypton, solar wind, noble gases, Genesis Mission, natural nuclear reactor, Oklo, Origin of fission xenon Bio: Meshik is the lead author of a study in the Oct. 19, 2007, issue of Science on the analysis of solar wind noble gases (neon and argon) from NASA's Genesis Mission. Meshik and colleagues will next study the solar wind samples for xenon and krypton. Meshik also analyzed the isotopic structure of noble gases produced in fission in a sample from the only known natural nuclear chain reaction site in the world in Gabon, West Africa. Analyzing a fragment of Gabon-site rock that's less than one-eighth of an inch, Meshik calculated that the precise isotopic structure of xenon in the sample reveals an operation that worked like a geyser. The reactor, active 2 billion years ago, worked on a 30-minute reaction cycle, accompanied by a 2.5-hour dormant period, or cool-down. WUSTL Contact Information:
Education:
Additional Background: Research Interests The current research interests of Professor Meshik focus on applications of noble gas isotopes to physics, nuclear chemistry and geo- and cosmo-chemistry. His research utilizes isotope mass-spectrometry and various methods of extraction of these gases from solids. There are three very exciting directions in his research: Investigation of ancient natural nuclear reactors sheds light on the reactor self regulation mechanisms and details of its operation. This research may provide us with some clue to capturing fission products and to safe storage of modern nuclear wastes. Developing and analyzing the collector materials from NASA Genesis space mission to accurately determine the isotopic composition of noble gases from solar wind. This research required the development of a new UV-laser extraction technique and a new generation of multi-collector noble gas mass-spectrometers. Experimental investigation of electroweak interactions responsible for extremely slow nuclear processes, such as double beta, double positron and/or electron capture decays. The rate of these processes allows checking some theories in nuclear physics and setting the upper limit of the neutrino rest mass. Selected Publications: A. Meshik (2006) Natürliche Kernreaktoren. Spectrum Der Wissenschaft, June 2006, 85-90. A. P. Meshik, C. M. Hohenberg, O. V. Pravdivtseva (2004) Record of cycling operation of the natural nuclear reactor in the Oklo/Okelobondo area in Gabon. Physical Review Letters 93, No.18, 182302-1-182302-4 G. R. Huss, A. P. Meshik, J. B. Smith and C. M. Hohenberg (2003) Presolar Diamond, Silicon Carbide, and Graphite in Carbonaceous Chondrites: Implications for Thermal Processing in the Solar Nebula. Geochimica et Cosmochimica Acta, 67, No. 24, 4823-4848. A. P. Meshik, C. M. Hohenberg, O. V. Pravdivtseva and Ya. S. Kapusta (2001) Weak decay of 130Ba and 132Ba: Geochemical measurements. Physical Review C, 64, 035205-1 - 035205-6. A. P. Meshik, K. Kehm and C. M. Hohenberg (2000) Anomalous xenon in zone 13 Okelobondo. Geochimica et Cosmochimica Acta 64, No.9, 1651-1661. A. P. Meshik, H. J. Lippolt and Yu. M. Dymkov (2000) Xenon geochronology of Schwarzwald pitchblendes. Mineralium Deposita 35, 190-205. |
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 Diana Lutz Senior Science Editor dlutz@wustl.edu (314) 935-5272
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Revised: Thursday, Nov. 5, 2009 
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