The National Science Foundation's (NSF) Major Research Instrumentation program has awarded $500,000 to a research group in the McDonnell Center for the Space Sciences in Arts and Sciences to complete the purchase and installation of a NANOSIMS, a one-of-its-kind ion microprobe. When completed, the NANOSIMS will be the first instrument in the world that will allow researchers to analyze the isotopic composition of cosmic dust particles so small that they can't even be seen with an optical microscope.
The NSF grant complements $1.1 million already committed by NASA and $500,000 awarded by the McDonnell Center toward the purchase of the NANOSIMS, according to Robert M. Walker, Ph.D., McDonnell Professor of physics and director of the McDonnell Center. The grants have been awarded to the center's extraterrestrial materials group headed by Walker.
The NANOSIMS, which is being manufactured in Paris and will be ready for delivery to Compton Hall late next winter, represents a breakthrough in ion microprobe technology, according to Walker.
A typical ion microprobe, which is a powerful instrument used to measure the isotopes of interstellar material, can measure grains weighing as little as a millionth of a millionth of a gram. By studying the isotopic composition of these particles, researchers are gaining new information on nuclear and chemical processes in stars and on conditions during the formation of the solar system.
When the NANOSIMS is completed, however, researchers will be able to measure particles 10 times smaller than what is possible with any current ion microprobe, including the one now at the McDonnell Center. Walker said that most of the detailed astrophysical information available today has come from studies of the isotopic and elemental compositions of individual grains. The NANOSIMS will extend the study of such grains from a micrometer in size -- not visible to the naked eye -- to grains with a thousand times less volume, which is more characteristic of interstellar dust.
"This instrument will open up a whole new world, allowing the study of a much wider range of presolar materials present in primitive meteorites," Walker said.
During the past 10 years -- since "stardust" was recovered from meteorites for the first time -- Walker; Ernst Zinner, Ph.D., director of the McDonnell Center's Ion Microprobe Laboratory; Tom Bernatowicz, Ph.D., professor of physics; and other center members have played leading roles in analyzing these grains in the laboratory and interpreting the results. It generally is believed that these grains originated in stellar atmospheres and predate the solar system.
The NANOSIMS is based on a novel ion optics design by George Slodzian, a professor at the University of Paris. For more than a decade, Walker, Zinner and Frank J. Stadermann, Ph.D., senior research scientist in physics, have worked on Slodzian's prototype instrument in Paris, testing the basic capabilities of the ion optics and other features of the design.
In collaboration with researchers at the Max Planck Institut für Chemie in Mainz, Germany, the group defined modifications that will be incorporated into the new instrument for superior elemental and isotopic measurements. The Max Planck Institut will receive a NANOSIMS a year after the McDonnell Center's instrument arrives.
The NANOSIMS combines high sensitivity with a small incident ion beam. Isotopic studies of tiny subgrains within circumstellar grains will become possible for the first time with the new instrument, as will isotopic measurements of unusual glassy objects, possibly interstellar in origin, found in interplanetary dust particles. The NANOSIMS also should have a substantial impact on terrestrial geoscience, Walker added.
Many former students and post-doctoral researchers who have worked with the center's current ion microprobe are now in charge of other ion microprobe laboratories around the world. The McDonnell Center group has made it a practice to make instruments and expertise available to other researchers, both inside and outside Washington University.
To date, more than three dozen researchers from 24 different institutions in six countries have collaborated on various ion microprobe projects, making the current probe a de facto international experimental facility. The NANOSIMS also will be available to the general scientific and technical communities, making it an important national resource for the future.
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