Sept. 28, 1995

current issue
archive / search

    Virtual journey to Earth's center: simulated planet core


    Keck Foundation gives $2 million for Advanced Photon Source laboratory The University is establishing a laboratory for high-pressure science at Argonne National Laboratory's Advanced Photon Source, thanks to a $2 million grant from the W.M. Keck Foundation of Los Angeles. The APS, when it is completed in 1996, will be the world's most brilliant source of Xrays.

    The new laboratory will enable scientists to simulate the pressures and temperatures of the earth's mantle and core. Scientists will use the APS's narrow, bright Xray beam to examine the geophysical processes that shape the earth and learn more about the forces that produce earthquakes deep within it.

    The new laboratory will be the cornerstone of the GeoSoilEnviroCARS sector of the APS, one of three sectors being developed by the Consortium for Advanced Radiation Sources (CARS). The 140-member consortium -- a collaboration with Northern Illinois University, Southern Illinois University and a large group of scientists from across the United States -- is managed by Chicago. The other two sectors are BioCARS, which is dedicated to studies in structural biology, and ChemMatCARS, which will be used for research in chemistry and materials science.

    GeoSoilEnviroCARS will develop a general-purpose national user facility for synchrotron research in the earth sciences. The facilities in the high pressure laboratory will enable scientists to use a diamond anvil cell -- capable of squeezing a sample to pressures exceeding those found at the center of the earth -- to probe the behavior of material in the earth's mantle and core. The diamond anvil cell will also enable astrophysicists to examine what happens to hydrogen under conditions that prevail deep within Jupiter's solid hydrogen core.

    "The APS will make these experiments entirely possible -- I wouldn't say routine, but entirely doable," said Dion Heinz, Associate Professor in Geophysical Sciences and a member of the team designing the scientific instruments for the high pressure laboratory. "The incredible brightness of the APS synchrotron radiation will enable us to get detailed information about the structure and temperature of heated materials under high pressure, which is impossible using current technology."

    Heinz said these techniques will allow scientists for the first time to X-ray high-pressure samples that have been heated to thousands of degrees, simulating the temperatures and pressures found deep within the earth.

    Another high-pressure device, a large-volume press, will allow scientists to study much larger samples than the anvil cell -- although at lower pressures -- and its precise temperature control will give them details of phase transitions, which have important implications for such processes as deep earthquakes within the earth.

    "The APS will let us produce much smaller and more intense X-ray beams than we've been able to produce in the past," said CARS Associate Director Mark Rivers, Senior Research Associate in Geophysical Sciences. "These very intense beams will dramatically increase the range of pressures and temperatures over which precise mineral structures can be determined, greatly expanding our understanding of processes deep within the earth."

    GeoSoilEnviroCARS has received additional funding from the National Science Foundation, the State of Illinois, the Department of Energy and the U.S. Department of Agriculture. The APS generated its first X-rays in March, and the first experiments are expected to begin late in the summer of 1996.