x-ray tomographic studies of stardust samples: a track and individual particles a. tsuchiyama 1, k....
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X-ray tomographic studies of Stardust samplX-ray tomographic studies of Stardust samples: a track and individual particleses: a track and individual particles
A. Tsuchiyama1, K. Uesugi2, T. Nakano3, T. Okazaki1,T. Nakamura4, A. Takeuchi2, Y. Suzuki2, and M. Zolensky
1 Department of Earth and Space Science, Osaka Univ.2 SPring-8/JASRI, 3 GSJ/AIST
4 Department of Earth and Planetary Sciences, Kyushu Univ., 5 JSC/NASA
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Two types of tomographic studiesTwo types of tomographic studiesat BL47XU/SPring-8at BL47XU/SPring-8
1.1. 3-D structures of 3-D structures of impact tracks impact tracks SUBTEAM: Bulk-compositionSUBTEAM: Bulk-composition Projection tomography (high resolution) Resolution: 0.5 or 0.195 m/pixel Samples: 4 tracks* in keystones with XRF (T. Nakamura)
2. 3-D structures of individual particlesindividual particles SUBTEAM: Mineralogy-Petrology Imaging tomography (ultra-high resolution) Resolution: 0.0425 m/pixel Samples: 4 particles removed from 2 tracks* with XRD at BL17/PF (T. Nakamura)
* Different tacks
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3D structures of impact tracks3D structures of impact tracks
Projection tomographyProjection tomography (0.5 or 0.195 m/pixel)Samples: 4 tracks (C2126,2,68,0; 32,0; 67,0; 47,0)Photon energy: 10 keVNo. of projection: 15003-D image: 2000x2000 matrix, 1312 slices
XRFPhoton energy 15 keVBeam size: 40x40 to 400x260 m
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ProcedureProcedure(1)(1) Optical microscopyOptical microscopy(2)(2) RadiographyRadiography Whole 2-D image of keystone
(3) XRFXRF Coarse mode: cover whole track Fine mode: individual particles
(4) TomographyTomography Coarse mode: cover whole track Fine mode: details of a track
Sample: C2126,2,68,0
Radiography (7.090 keV: tile image)
Optical microscopy
XRFTomography
(vertical slice: 5 tiles)
Tomography(CT slice)
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CT slice images (CT slice images (C2126,2,68,0)C2126,2,68,0)
particle
particleradial crack
condensed aerogel
4a/0564
main trackcondensed aerogel
subtrack-5(terminal particle)
subtrack-1
subtrack-3
4b/1008
Dark space: track hole with radial cracksradial cracksBright wall: condensed aerogelcondensed aerogel (melted?) with very fine particles?White: captured particles particles
Track is bifurcated into mainmain and sub-trackssub-tracks..Particles are present along tracks and radial cracks as well as the
main track terminal.
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CT images parallel to the track (C2126,2,68,0)
C2126,2,68,0 CT images nearly parallel to the track
Many particles are present along the mainmain and subtrack-subtrack-11.
slice 229slice 219 slice 239
main track
subtrack-1
main track
main track
radial crack
terminal particle
main track
bifurcation
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Track: Bird’s eye view (Track: Bird’s eye view (C2126,2,68,0C2126,2,68,0))
GrayGray: track hole and radial cracksBlueBlue: condensed aerogelRedRed: captured particlesTrack is bifurcated into 5 or 6. MainMain and subtrackssubtracks have terminal particles, respectively.Many particles are present along the bifurcated tracks.
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Track size Track size vsvs. XRF data (. XRF data (C2126,2,68,0C2126,2,68,0))
volume (m3)
mode(%)
track 7.788E+06 78.75
particles 3.155E+04 0.32
condensed aerogel
2.070E+06 20.93
total 9.889E+06 100.00
diameter (m)
entrance 79.9x60.5
length (m)
main track 2484
subtrack-1 1672
subtrack-2 1353
subtrack-3 1107
subtrack-4 1027
subtrack-5(?) 756
Whole Fe mass: 6.66x10-11 g XRF dataXRF dataEstimated mass (whole grain): 7.6x10-10 g
Fe mass/track volumeFe mass/track volume: 8.56x10-6 g/cm3
Estimated whole mass/track volume: 9.7x10-5 g/cm3
if density=1 g/cm3 : 0.01 vol.%
If track volume is proportional to mass, we mayevaluate volatile/solid ratiovolatile/solid ratio among different tracks. track volume ↔ kinetic E = 1/2mv2 (v∼const.)
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a
b
c
d
e
f
Track bulb: Bird’s eye view (Track bulb: Bird’s eye view (C2126,2,68,0C2126,2,68,0))
U-shaped radial crackU-shaped radial crack (main: arrow-aarrow-a and sub: arrow-barrow-b)
Crack along the central axis of the U-shaped crack: arrow-carrow-c
Subtrack-4 grows from the central crack: arrow-darrow-d (each subtracksubtrack seem to grow from a crackgrow from a crack)
Wavy radial crack: arrow-earrow-e
Some particles are in radial cracks: arrow-farrow-f
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3D structures of individual particles3D structures of individual particlesImaging tomographyImaging tomography (0.0425 m/pixel)Samples: 4 particles (C2004.1.44.3, C2054.0.35.6; .5,; .4)Photon energy: 8 keVNo. of projection: 36003-D image: 2000x2000 matrix, 1312 slices
XRDBL17/Photon Factory, Japan
The results are presented by T.NakamuraThe results are presented by T.Nakamura
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ConclusionsConclusions
• Whole dust particleWhole dust particle less fragile particlesless fragile particles + fragile aggregate of fine particlesfragile aggregate of fine particles ← 3-D structure of track ← 3-D structures of individual particles less fragile particles: crystalline fragile aggregate: amorphous-rich (mixture with aerogel)
• Not easy to reconstruct whole dust particle texture completely by tomography alone
• Fe mass/track volumeFe mass/track volume → whole dust particle/track volueme: ~ 0.01 vol.% → may estimate volatile/solid ratios of whole dusts particles among tracks
• Crystalline particles evidence of melting?evidence of melting? (SEM/EBSD or TEM study required) fractured surface