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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.

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Presentation on theme: "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."— Presentation transcript:

1 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

2 K–Ar dating 2 40 K 40 C a 40 Ar β ~90% EC ~10% Half-life ~1.8 By Rock: –Ar degassing occurs before solidified The dominant source of 40 Ar is 40 K decay. –Ca is abundant Difficulty to estimate the amount of 40 K originated Ca. Ca 40 K/K ~10 -4

3 K–Ar dating 3 Ice: –K has a high solubility in water –Ar degassing also occurs before frozen. The dominant source of 40 Ar in ice should be also 40 K decay. Possibility of K-Ar dating on Europa [Swindle et al., 2005] Europas surface: tens of My. Ganymedes surface: hundreds of My.

4 LIBS: Laser Induced Breakdown Spectroscopy 4 Optical elemental analysis technique –Ablation: a high intensity pulse laser Pulse laser Ablation

5 LIBS: Laser Induced Breakdown Spectroscopy 5 Optical elemental analysis technique –Ablation: a high intensity pulse laser –Plasma emission spectroscopy: spectrometer Spectrometer Plasma emission

6 K-Ar dating using LIBS (MSL/ChemCam) 6 MSL/Chemcam NASA K LIBS in UV-Vis-IR range K emission lines: 767nm, 770nm

7 K-Ar dating using LIBS (MSL) 7 K LIBS in UV-Vis-IR range K emission lines: 767nm, 770nm Ar Vacuum chamber and mass spectrometer Measuring the mass of the sample and the amount of outgassing Ar with heating. Pulse Laser Spectrometer target

8 K-Ar dating using LIBS (MSL) 8 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. Vacuum Chamber Pulse Laser Spectrometer Q Mass arm robotic

9 target Determination of quantity of Ar using LIBS 9 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 Pulse Laser Spectrometer Vacuum Chamber Q Mass arm robotic

10 Determination of quantity of Ar using LIBS 10 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

11 Determination of quantity of Ar using LIBS 11 Nd:YAG Sample Grating MCP with Phosphor K-feldspar (Age and composition are unknown..) Ar Lamp Rikkyo Univ.

12 Preliminary result 12 K-feldspar Still in preparation. Spectrum of Ar Lamp FWHM is 0.3 nm. Preliminary result

13 Toroidal grating 4800gr/mm Banpass filter for K ~767nm Detector MCP+multi anord Or MCP+Phosphor+CCD 100mm 25mm 62.5mm Blue: Ar 106.7 nm Pink: He 58.4 nm Red: 0-order 25mm x 25mm x 62.5mm < 105 g w/o Pulse Laser Optical Design

14 Ganymede Lander & Orbiter (JUICE) Lander: In-situ K-Ar Absolute age One point JUICE: Crater-count Global Map Relative age Complementary NASA

15 Another activity on LIBS SELENE-2 (Lunar Rover, Pre-Project) 15 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.

16 Optical design of Telescope 16 FOV: φ10mm Spectral range: 360-1064nm

17 Interface point (Optics) Spain Dr. F. Rull Movement France Dr. O. Ganault Dr. 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

18 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


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