Presentation is loading. Please wait.

Presentation is loading. Please wait.

Zheng-Tian Lu Physics Division, Argonne National Laboratory Department of Physics, University of Chicago Supported by Department of Energy, Office of Nuclear.

Similar presentations


Presentation on theme: "Zheng-Tian Lu Physics Division, Argonne National Laboratory Department of Physics, University of Chicago Supported by Department of Energy, Office of Nuclear."— Presentation transcript:

1 Zheng-Tian Lu Physics Division, Argonne National Laboratory Department of Physics, University of Chicago Supported by Department of Energy, Office of Nuclear Physics National Science Foundation, Earth Science Division JLab FEL – Opportunity for a New Generation of Ultrasensitive Trace Analyzer of Noble Gas Isotopes

2 Nobel Gas Tracers Half-lifeAtmospheric isotopic abundance Sources 85 Kr10.8 yr2x Nuclear fuel reprocessing 39 Ar269 yr8x Cosmic-ray induced reaction 81 Kr229,000 yr6x Cosmic-ray induced reaction

3 Polar Ice as a natural archive temperature precipitation gas composition volcanic eruption solar variability... Number of 81 Kr atoms in 1 liter of : Air 20,000 Water 1,000 Ice 1, Kr, 82 Kr Kr Cosmic p, n 81 Kr Radio-Krypton Dating ( 81 Kr (t 1/2 = 230kyr, I.A.= 6 x )

4 National Superconducting Cyclotron Laboratory Michigan State University Full stripping at high energy (~ 4 GeV) for isobar separation: 81 Kr 36+ vs. 81 Br 35+. Accelerator Mass Spectrometry of Kr-81 W. Kutschera et al., NIM B29, 241 (1994); P. Collon et al., NIM B123, 122 (1997) First 81 Kr dating: groundwater in GAB -- P. Collon et al., EPSL 182, 103 (2000)

5 Methods of Trace-Isotope Analysis at PPT Level Muller, Physics Today AMS ATTA LLC – Low Level Decay Counting Willard Libby, Science (1949) AMS – Accelerator Mass Spectrometry R. A. Muller, Science (1977) Nelson et al., Science (1977) Bennett et al., Science (1977) ATTA – Atom Trap Trace Analysis Chen et al. Science (1999)

6 Neutral Atom Trap Sodium, NIST Laser Trapping and Cooling - a quick primer

7 "for development of methods to cool and trap atoms with laser light" Steve ChuClaude Cohen-Tannoudji William Phillips 1997 Nobel Physics Laureates

8 Discharge Source Transverse Cooling Beam Chopper 2D Focusing Zeeman Slower MOT CCD Camera Atom Trap Trace Analysis of Krypton 5p[5/2] 3 5s[3/2] 2 4p 6 Ground-level Metastable 40 sec 811 nm 10 eV electron collision

9 = 1600 counts = counts Single Atom Detection

10 Counting 81 Kr and 85 Kr

11 One Million Years of Nubian Aquifer Groundwater History Sturchio et al., Geophys. Res. Lett. (2004) Groundwater at six sites dated; Flow direction and speed measured; Source determined. Uweinat Uplift kyr kyr kyr kyr kyr

12 81 Kr Dating: From Dream to Practice Efficiency Water or Ice Sample Size (L) Groundwater Polar Ice LLC 1969 AMS 1997 ATTA ATTA ATTA ATTA-1: Chen et al., Science (1999) ATTA-2: Du et al., Geophys. Res. Lett. (2003) ATTA-3: Jiang et al., Phys. Rev. Lett. (2011) ATTA-4 JLab FEL Present Status of ATTA-3: Selectivity requirement: Done; Efficiency requirements: Practical, but far from perfection

13 Advantages over the existing RF discharge method: Improve efficiency Metastable production efficiency Collimate atomic beam Reduce sample loss and contamination ATTA-4 with JLab FEL Optical production of Kr* via two-photon excitation: 124 nm nm Young et al., J. Phys. B (2002) Ding et al. RSI (2007) 5s[3/2] 0 2 4p 6 Ground Metastable 5p[3/2] nm 5s[3/2] nm Proposal to determine two-photon excitation rate in Summer, 2011 Zheng-Tian Lu, William Williams (Argonne) Charles Sukenik, Grady White (ODU) Gwyn Williams, Michelle Shinn et al. (JLab)

14 Kevin Bailey Wei Jiang Zheng-Tian Lu Peter Mueller Tom OConnor Will Williams Argonne Atom Trappers ATTA Team

15 Collaborators Neil C. SturchioUniversity of Illinois at Chicago Andrew M. DavisUniversity of Chicago L. Young & R. DunfordChemistry Division, Argonne Shuiming HuUniversity of Science & Technology of China B. Mack KennedyLawrence Berkeley National Lab Roland PurtschertUniversity of Bern Charles SukenikOld Dominion University


Download ppt "Zheng-Tian Lu Physics Division, Argonne National Laboratory Department of Physics, University of Chicago Supported by Department of Energy, Office of Nuclear."

Similar presentations


Ads by Google