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| School of Ocean and Earth Science and Technology . University of Hawai‘i at Mānoa | |||
W. M. Keck Cosmochemistry Laboratory
The W. M. Keck Cosmochemistry Laboratory, established in 2006, is a catalyst for interdisciplinary research into the origin of the solar system. The centerpiece of the laboratory is a state-of-the-art Cameca ims 1280 ion microprobe, the latest version of the Cameca large-geometry magnetic sector secondary ion mass spectrometer (SIMS). This instrument is capable of in situ measurements of chemical and isotopic compositions of many types of natural samples at a spatial resolution of tens of micrometers down to submicrometer scales. Our cosmochemistry research utilizes samples of meteorites, interplanetary dust particles (IDPs), and samples returned from NASA missions, such as the Apollo Moon missions, the Stardust mission to comet Wild 2, the Genesis Mission to capture solar wind, and future sample-return missions to asteroids, the Moon and eventually, Mars. The W. M. Keck Cosmochemistry Laboratory is open to researchers from around the world for collaborative research on cosmochemistry. Funding for the laboratory was provided by the W. M. Keck Foundation, NASA, and the University of Hawai'i. Our broad research themes: Presolar grains and comet dust, Mixing of reservoirs and processing of materials in the early solar system, Early solar system chronology by measuring decay products of short-lived radionuclides. Cameca ims 1280 ion microprobe [Click on the photos below for enlargements.]
See a listing of the features of the Cameca ims 1280 ion microprobe in our lab. We will upgrade this highly capable instrument with additional state-of-the-art technologies to address the unique challenges of research on early solar-system materials. We will add a secondary-electron detector to aid in locating tiny grains for analysis. The secondary-electron image in the ion microprobe can be directly correlated with the secondary-electron image from an SEM. To help precisely position the sample under the primary beam during automated analyses and to facilitate using sample locations determined by an automated system on the SEM, we will add optical encoders to the sample stage. The SCAPS Detector The University of Hawai'i Cameca ims 1280 has a new solid state imaging detector called SCAPS. A stacked CMOS-type active pixel sensor for charged particles, SCAPS was developed at the Tokyo Institute of Technology (Nagashima et al., 2001). Kazuhide Nagashima, a member of our research team, is a co-developer of this unique detector. The SCAPS detector will permit direct ion imaging of fine-grained samples and will permit identification of isotopically or chemically anomalous grains at a spatial resolution of a few tenths of a micron (Nagashima et al., 2004; Kobayashi et al., 2005). SCAPS is composed of a rectangular array of 608x576 independent micro-detectors or "pixels." When placed in the position where the channel plate normally sits, SCAPS can collect two-dimensional ion images. The SCAPS detector has sufficiently well understood and reproducible characteristics to permit quantitative isotope analysis in two dimensions using a stigmatic SIMS such as the Cameca 1280. SCAPS has several advantages over conventional systems, including two-dimensional detection, wide dynamic range, no insensitive period, direct detection of charged particles, constant ion sensitivities among nuclides, and a high degree of robustness. The SCAPS can measure high ion flux with an accuracy of within twice the statistical error and with a detection limit corresponding to 3 ions. While SCAPS is a prototype device with its own limitations, it provides a new way of producing abundance and isotope-ratio images of fine-grained samples. The Cameca 1270 equipped with SCAPS at the Tokyo Institute of Technology has demonstrated that high precision isotope ratio imaging at micro-scale under high MRP is possible (Yurimoto et al., 2003).
Origin of the Solar System We will use the Cameca ims 1280 and associated equipment to investigate the origin of the solar system. The research can be thought of as consisting of three basic types of investigations: 1) Studies of the raw materials that were the building blocks for the solar system, including presolar grains from meteorites, interplanetary dust particles, and comet samples returned by the Stardust mission. 2) Studies of the timing of events during the formation of the solar system. Chronology will be investigated through studies of short-lived radionuclides. 3) Studies of early solar system processes, which we will investigate through measurements of chemical compositions, trace-element abundances, isotopic fractionations, and the unique variations exhibited by oxygen isotopes. In addition to the laboratory work, our studies have strong interdisciplinary collaborations with the astronomers and astrophysicists at the Institute for Astronomy at the University of Hawai'i and around the world, and also with the University of Hawai'i Astrobiology Institute. The people responsible for the success of the W. M. Keck Cosmochemistry Laboratory:
References Conty C. (1990) SIMS VII, 831-834. Kobayashi S. et al. (2005) LPSC XXXVI, Abstract #1931. Nagashima K. et al. (2001) Surf. Interf. Anal. 31, 131-137. Nagashima K. et al. (2004) Nature 428, 921-923. Nguyen, A. and Zinner E. (2004) Science 303, 1496-1499. Yurimoto H. et al. (2003) Appl. Surf. Sci. 203-204, 793-797. Text and images courtesy G. R. Huss. For more information on the W. M. Keck Cosmochemistry Laboratory at HIGP contact Gary Huss, Kazuhide Nagashima or Sasha Krot. Listing of publications resulting from research carried out to date with our Cameca ims 1280 ion microprobe. For a general-audience overview of how the instrument works and its applications in cosmochemistry read the February, 2006 PSRD article "Ion Microprobe." We hosted the 6th Biennial Geochemical SIMS Workshop, November 2-4, 2011, and provide this link to the program (BGSW6). |
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