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Tim Elam Senior Principal Physicist wtelam@apl.washington.edu Phone 206-685-3092 |
Research Interests
X-ray Spectroscopy
Biosketch
Dr. Tim Elam's main research interest is X-ray spectroscopy. He has worked in the areas of X-ray absorption, emission, fluorescence, and non-resonant inelastic scattering. His present efforts focus on using X-ray fluorescence in difficult environments. He has built several downhole X-ray fluorescence spectrometers to measure heavy metal contaminants in soils and sediments and to make in-situ measurements of diffusion of stable isotopes of nuclear waste elements through native rock without radioactivity. He is now the Chief Spectroscopist for the Planetary Instrument for X-ray Lithochemistry (PIXL) on the Perseverance rover and the hardware lead for the APL-UW Ice Diver.
He is past Chair of the Denver X-ray Conference and was the American Institute of Physics Congressional Science Fellow for 1991. He has more than 100 publications in refereed scientific journals and holds 5 patents.
Education
B.S. Physics, Mississippi State University, 1973
M.S. Physics, University of Maryland, 1977
Ph.D. Physics, University of Maryland, 1979
Projects
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Borehole X-Ray Fluorescence Spectrometer (XRFS) The XRFS was built by APL-UW under a NASA contract from the Langley Research Center; it is designed to be deployed down a pre-drilled hole for exploration and elemental analysis of subsurface planetary regolith. |
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Videos
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PIXL Blasts Off for Mars PIXL is an X-ray spectrometer integrated into the Perseverance rover that began its journey on July 30th. After landing in early 2021, PIXL will measure the microstructure of rocks in search of fossils and evidence of ancient Martian microbial life. |
15 Sep 2020
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PIXL on Mars 2020 Mission PIXL is the Planetary Instrument for X-Ray Lithochemistry. APL-UW's Tim Elam, the mission's 'chief spectroscopist', is collaborating with a NASA team that integrated a micro X-ray fluorescence instrument on the rover Perseverance that landed on Mars in February 2020. |
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24 Feb 2016
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PIXL's purpose is to measure the microstructure of rocks in search of fossils -- biosignatures of life forms preserved in the rocks. PIXL will tell scientists the composition of materials and their structure -- that is, how the elements are arranged. It's this map of elemental spatial distribution that's critical for finding biosignatures. |
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Ice Diver: A Thermal Ice Penetrator Ice Diver is a thermal melt probe system for extensive, low-cost sensor deployment to the bed of the Greenland Ice Sheet, where it will measure water pressure in subglacial hydrological networks. |
23 May 2013
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Publications |
2000-present and while at APL-UW |
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A statistical approach to removing diffraction from X-ray fluorescence spectra Orenstein, B.J., D.T. Flannery, L.W. Casey, W.T. Elam, C.M. Heirwegh, M.W.M. Jones, "A statistical approach to removing diffraction from X-ray fluorescence spectra," Spectrochim. Acta, Part B, 200, doi:10.1016/j.sab.2022.106603, 2023. |
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1 Feb 2023 ![]() |
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Diffraction peaks can lead to inaccurate elemental abundances in X-ray fluorescence maps. However, manually removing diffraction peaks is laborious while existing automated methods unnecessarily remove significant volumes of fluorescence data. Here we propose a new automated method to remove diffraction from multiple-detector spectra based on a statistical threshold. This method eliminates only the diffraction peaks from the spectra, retaining more of the fluorescence data and increasing the information content available for diffraction-free elemental quantification and mapping. By retaining the majority of the fluorescence data, the proposed method does not require an increase in dwell times or additional data to be collected to compensate for the removed fluorescence data. This method is therefore particularly valuable in instances where measurement time and data volumes are highly restricted, such as for instruments on planetary exploration missions like the Planetary Instrument for X-ray Lithochemistry on NASA's Mars 2020 mission Perseverance Rover. |
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The focused beam X-ray fluorescence elemental quantification software package PIQUANT Heirwegh, C.M., W.T. Elam, L.P. O'Neil, K.P. Sinclair, and A. Das, "The focused beam X-ray fluorescence elemental quantification software package PIQUANT," Spectrochim. Acta, Part B, 196, doi:10.1016/j.sab.2022.106520, 2022. |
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1 Oct 2022 ![]() |
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Adoption of a robust X-ray fluorescence spectroscopy quantification and spectrum fitting routine calls for careful consideration on the inner workings and databases incorporated in its architecture. For analysis of micro-XRF data returned from the Planetary Instrument for X-ray Lithochemistry (PIXL), integrated on the Mars 2020 Perseverance rover, the University of Washington and the National Aeronautics and Space Administration (NASA) have invested in the production of an in-house micro-XRF software package, PIQUANT, capable of supporting quantitative elemental analysis of whole rock and geological materials. The PIQUANT software uses an iterative fundamental parameters physics-based model to convert X-ray peak intensity into elemental concentration, and has minimal reliance on calibration using standards. It also incorporates polycapillary optic transmission correction to account for photon passage in the X-ray optic of micro-XRF systems. This work introduces the key features of PIQUANT's architecture, its databases, models, assumptions and summarizes features available as part of the analysis products it generates. A working example of a quantification process available with this software is presented within. |
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An olivine cumulate outcrop on the floor of Jezero crater, Mars Liu, Y., and 71 others including W.T. Elam and K. Sinclair, "An olivine cumulate outcrop on the floor of Jezero crater, Mars," Science, 377, 1513-1519, doi:10.1126/science.abo2756, 2022. |
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25 Aug 2022 ![]() |
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The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We find that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some Martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multi-stage cooling of a thick magma body. |
In The News
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UW physics professor helps design instrument on Mars Perseverance rover KIRO Radio, MyNorthwest Staff University of Washington professor and physicist Tim Elam explained on KIRO Nights that he is part of a team that designed an instrument to create chemical images of rocks on Mars. Elam says he’s been working on his portion of this project for more than eight years, from the original proposal for the instrument to now having hardware on the way to Mars. |
18 Feb 2021
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How the pandemic is changing the protocol for NASA's Mars landing and how to watch it happen GeekWire, Alan Boyle Because of the yearlong COVID-19 pandemic, the hundreds of scientists and engineers behind the Perseverance rover mission have had to work almost exclusively from home. On the big day, only a minimal crew of ground controllers will be on duty at NASA’s Jet Propulsion Laboratory in Pasadena, CA. APL-UW Physicist Tim Elam, too, will be watching from home on February 18th. |
17 Feb 2021
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NASA's Mars Perseverance rover mission serves as ultimate test for working from home (planet) GeekWire, Alan Boyle Tim Elam is an expert on X-ray fluorescence at UW’s Applied Physics Laboratory. So when scientists and engineers were brought onto the team for Perseverance’s Planetary Instrument for X-ray Lithochemistry, or PIXL, Elam was a natural addition. |
29 Jul 2020
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