In-situ K- Ar dating using LIBS in the VUV range
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In-situ K-Ar dating using LIBS in the VUV range Shingo Kameda 1 , Yuichiro Cho 2 , Yasuhito Sekine 2 , Seiji Sugita 2 1 Rikkyo University, 2 The University of Tokyo 1
description
In-situ K- Ar dating using LIBS in the VUV range. Shingo Kameda 1 , Yuichiro Cho 2 , Yasuhito Sekine 2 , Seiji Sugita 2 1 Rikkyo University, 2 The University of Tokyo. K – Ar dating. 40 Ca. Ca. Ca. β ~90%. 40 K. 40 K/K ~10 -4. 40 Ar. Half-life ~1.8 By. EC ~10%. Rock: - PowerPoint PPT Presentation
Transcript of In-situ K- Ar dating using LIBS in the VUV range
In-situ K-Ar dating using LIBS in the VUV range
Shingo Kameda1, Yuichiro Cho2, Yasuhito Sekine2, Seiji Sugita2
1 Rikkyo University, 2 The University of Tokyo
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K–Ar dating
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40K
40Ca
40Ar
β ~90%
EC ~10%
Half-life~1.8 By• Rock:
– Ar degassing occurs before solidifiedThe dominant source of 40Ar is 40K decay.– Ca is abundant Difficulty to estimate the amount
of 40K originated Ca.
Ca Ca40K/K ~10-4
K–Ar dating
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• Ice:– K has a high solubility in water– Ar degassing also occurs before frozen. The dominant source of 40Ar in ice should be also 40K decay.
・ Possibility of K-Ar dating on Europa [Swindle et al., 2005]
Europa’s surface: tens of My. Ganymede’s surface: hundreds of My.
LIBS: Laser Induced Breakdown Spectroscopy
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• Optical elemental analysis technique– Ablation: a high intensity pulse laser
Pulse laser Ablation
LIBS: Laser Induced Breakdown Spectroscopy
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• Optical elemental analysis technique– Ablation: a high intensity pulse laser– Plasma emission spectroscopy:
spectrometer
SpectrometerPlasma emission
K-Ar dating using LIBS (MSL/ChemCam)
6MSL/Chemcam NASA
K• LIBS in UV-Vis-IR range• K emission lines: 767nm, 770nm
K-Ar dating using LIBS (MSL)
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K• LIBS in UV-Vis-IR range• K emission lines: 767nm, 770nm
Ar ・ Vacuum chamber and mass spectrometerMeasuring the mass of the sample and the amount of outgassing Ar with heating.
Pulse Laser
Spectrometer
target
K-Ar dating using LIBS (MSL)
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K• LIBS in UV-Vis-IR range• K emission lines: 767nm, 770nm
Ar• Vacuum chamber, mass spectrometer,…Measuring the mass of the sample and the amount of outgassing Ar with heating.
VacuumChamberPulse Laser
Spectrometer
Q Mass
armrobotic
target
Determination of quantity of Ar using LIBS
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New idea to observe Ar emission line.Ar emission lines: 104.8nm and 106.7nm・ Vacuum chamber is not necessary on the airless body. Less mass
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Pulse Laser
Spectrometer VacuumChamber Q Mass
armrobotic
Determination of quantity of Ar using LIBS
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New idea to observe Ar emission line.Ar emission lines: 104.8nm and 106.7nm・ Vacuum chamber is not necessary on the airless body. Less mass・ Remote Sensing (1m TBC)
No experiment for Ar in rocks yet. (LIBS experiment for Ar atmosphere was performed.)
Pulse Laser
Spectrometer
target
Determination of quantity of Ar using LIBS
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Nd:YAG Sample
Grating
MCP with Phosphor
• K-feldspar(Age and composition are unknown..)
Ar Lamp
Rikkyo Univ.
Preliminary result
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• K-feldspar
• Still in preparation.←Spectrum of Ar Lamp • FWHM is 0.3 nm.• Preliminary result
102 104 106 108 1100
1000
2000
3000
4000
5000
Inte
nsity
, AD
U
Wavelength, nm
0.31nm
Toroidal grating4800gr/mm
Banpass filter for K~767nm
Detector
MCP+multi anordOr
MCP+Phosphor+CCD
100mm
25mm
62.5mm
Blue: Ar 106.7 nm Pink: He 58.4 nmRed: 0-order25mm x 25mm x 62.5mm < 105 g w/o Pulse Laser
Optical Design
Ganymede Lander & Orbiter (JUICE)
Lander: In-situ K-Ar Absolute ageOne point
JUICE: Crater-countGlobal MapRelative age
ComplementaryNASA
Another activity on LIBSSELENE-2 (Lunar Rover, ‘Pre’-Project)
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• ChemCam-like LIBS is too big (9-11kg) to install on the gimbal on the mast unit of the SELENE-2 rover.Install LIB-S2 on the body to reduce the total mass. (Fiber becomes unnecessary.)3.5 kg
• Closer to the ground Distance range can be reduced.
Optical design of Telescope
16• FOV: φ10mm Spectral range: 360-1064nm
Interface point (Optics)SpainDr. F. Rull
Movement
FranceDr. O. GanaultDr. S. Maurice
Install Visible LD in Japan on the base plate.Align Laser & Spectrograph with Vis. LD in France & Spain.Fix them on the B/P. 17
• Movable telescope• Automatic focus adjustment
Specification• Distance: 1.0 – 1.5 m• Spectral range: 360 – 1064 nm• Laser intensity: ~10 mJ/pulse
(Nd:KGW, almost the same as ChemCam)• Laser spot diameter: < 300 um• FOV: φ10mm at the target plane• Spatial resolution of
the imager: 30um/pix• Scanning gap: ~300um• Mass: 3.52kg• Power: 7W(max)• 3 movement systems:#1 wide-range vertical movement,#2 short-range horizontal scanning,#3 focus adjustment 18
