Presentation on theme: "In-situ K-Ar dating using LIBS in the VUV range"— Presentation transcript:
1In-situ K-Ar dating using LIBS in the VUV range Shingo Kameda1, Yuichiro Cho2,Yasuhito Sekine2, Seiji Sugita21 Rikkyo University, 2 The University of Tokyo
2K–Ar dating Rock: Ar degassing occurs before solidified 40CaCaCaβ ~90%40K40K/K ~10-440ArHalf-life~1.8 ByEC ~10%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.
3K–Ar datingIce:K has a high solubility in waterAr 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.
4LIBS: Laser Induced Breakdown Spectroscopy Optical elemental analysis techniqueAblation: a high intensity pulse laserPulse laserAblation
5LIBS: Laser Induced Breakdown Spectroscopy Optical elemental analysis techniqueAblation: a high intensity pulse laserPlasma emission spectroscopy: spectrometerSpectrometerPlasma emission
6K-Ar dating using LIBS (MSL/ChemCam) LIBS in UV-Vis-IR rangeK emission lines: 767nm, 770nmMSL/Chemcam NASA
7K-Ar dating using LIBS (MSL) LIBS in UV-Vis-IR rangeK emission lines: 767nm, 770nmAr・Vacuum chamber and mass spectrometerMeasuring the mass of the sample and the amount of outgassing Ar with heating.targetSpectrometerPulse Laser
8K-Ar dating using LIBS (MSL) LIBS in UV-Vis-IR rangeK emission lines: 767nm, 770nmArVacuum chamber, mass spectrometer,…Measuring the mass of the sample and the amount of outgassing Ar with heating.roboticarmSpectrometerVacuumChamberQ MassPulse Laser
9Determination of quantity of Ar using LIBS 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 massrobotictargetarmSpectrometerVacuumChamberQ MassPulse Laser
10Determination of quantity of Ar using LIBS 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.)targetSpectrometerPulse Laser
11Determination of quantity of Ar using LIBS MCP with PhosphorGratingSampleNd:YAGK-feldspar(Age and composition are unknown..)Ar LampRikkyo Univ.
12Preliminary result K-feldspar Still in preparation. ←Spectrum of Ar LampFWHM is 0.3 nm.Preliminary resultK-feldspar
13Optical Design 25mm x 25mm x 62.5mm < 105 g w/o Pulse Laser Toroidal grating4800gr/mmBanpass filter for K~767nm62.5mm100mmDetectorMCP+multi anordOrMCP+Phosphor+CCD25mmBlue: Ar nm Pink: He 58.4 nmRed: 0-order25mm x 25mm x 62.5mm < 105 g w/o Pulse Laser
15Another activity on LIBS SELENE-2 (Lunar Rover, ‘Pre’-Project) 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 kgCloser to the ground Distance range can be reduced.
16Optical design of Telescope FOV: φ10mm Spectral range: nm
17Interface point (Optics) Spain Dr. F. RullFranceDr. O. GanaultDr. S. MauriceInstall Visible LD in Japan on the base plate.Align Laser & Spectrograph with Vis. LD in France & Spain.Fix them on the B/P.MovementMovable telescopeAutomatic focus adjustment
18Specification 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 umFOV: φ10mm at the target planeSpatial resolution ofthe imager: 30um/pixScanning gap: ~300umMass: 3.52kgPower: 7W(max)3 movement systems:#1 wide-range vertical movement,#2 short-range horizontal scanning,#3 focus adjustment