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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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Avoiding slush for hot-point drilling of glacier boreholes Hills, B.H., D.P. Winebrenner, W.T. Elam, and P.M.S. Kintner, "Avoiding slush for hot-point drilling of glacier boreholes," Ann. Glaciol., 62, 166-170, doi:10.1017/aog.2020.70, 2021. |
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1 Apr 2021 ![]() |
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Water-filled boreholes in cold ice refreeze in hours to days, and prior attempts to keep them open with antifreeze resulted in a plug of slush effectively freezing the hole even faster. Thus, antifreeze as a method to stabilize hot-water boreholes has largely been abandoned. In the hot-point drilling case, no external water is added to the hole during drilling, so earlier antifreeze injection is possible while the drill continues melting downward. Here, we use a cylindrical Stefan model to explore slush formation within the parameter space representative of hot-point drilling. We find that earlier injection timing creates an opportunity to avoid slush entirely by injecting sufficient antifreeze to dissolve the hole past the drilled radius. As in the case of hot-water drilling, the alternative is to force mixing in the hole after antifreeze injection to ensure that ice refreezes onto the borehole wall instead of within the solution as slush. |
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In-situ X-ray fluorescence to investigate iodide diffusion in opalinus clay: Demonstration of a novel experimental approach Jaquenoud, M., and 9 others including W.T. Elam, "In-situ X-ray fluorescence to investigate iodide diffusion in opalinus clay: Demonstration of a novel experimental approach," Chemosphere, 269, doi:10.1016/j.chemosphere.2020.128674, 2021. |
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1 Apr 2021 ![]() |
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During the last two decades, the Mont Terri rock laboratory has hosted an extensive experimental research campaign focusing on improving our understanding of radionuclide transport within Opalinus Clay. The latest diffusion experiment, the Diffusion and Retention experiment B (DR-B) has been designed based on an entirely different concept compared to all predecessor experiments. With its novel experimental methodology, which uses in-situ X-ray fluorescence (XRF) to monitor the progress of an iodide plume within the Opalinus Clay, this experiment enables large-scale and long-term data acquisition and provides an alternative method for the validation of previously acquired radionuclide transport parameters. |
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Optimized Compton fitting and modeling for light element determination in micro-X-ray fluorescence map datasets O'Neil, L.P., D.C. Catling, and W.T. Elam, "Optimized Compton fitting and modeling for light element determination in micro-X-ray fluorescence map datasets," Nucl. Instrum. Methods Phys. Res., Sect. B, 436, 173-178, doi:10.1016/j.nimb.2018.09.023, 2018. |
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1 Dec 2018 ![]() |
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The Planetary Instrument for X-ray Lithochemistry (PIXL) is an X-ray fluorescence instrument scheduled to fly to Mars on NASA's 2020 rover (Allwood et al., 2015). It will be capable of quantifying elements with atomic number of at least 11 using X-ray fluorescence (XRF), but the detector window blocks fluorescence from lighter elements. Important elements otherwise invisible include carbon, oxygen, and nitrogen, which can make up anions in minerals of scientific interest. X-rays scattered by all elements can be detected, so the ratio of Compton to Rayleigh scatter may be measured and used to infer the presence of elements for which there is no detectable fluorescence. We have refined a fundamental parameters model to predict the Compton/Rayleigh ratio for any given composition that can be compared to an experimentally measured ratio. We compare with a published Monte Carlo model (Schoonjans et al., 2012) and to experimental values for a set of seven materials. Compton/Rayleigh ratios predicted by the model are in good, though imperfect, agreement with experimental measurements. A procedure for consistently computing the Compton/Rayleigh ratio from a noisy spectrum has also been developed using a variation on a common background removal method and peak fitting. |
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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Inventions
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Thermal Ice Melt Probe Including Water Jetting and Clean Sampling Record of Invention Number: 49014 |
Disclosure
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13 Jul 2020
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PIQUANT X-ray Fluorescence Quantification Software Record of Invention Number: 48292 |
Disclosure
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27 Mar 2018
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In-Situ Elemental Analyzer Using Wavelength Dispersive X-ray Fluorescence Record of Invention Number: 48011 Tim Elam, Gerald Seidler |
Disclosure
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28 Mar 2017
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