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Zheng-Tian Lu Physics Division, Argonne National Laboratory

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Presentation on theme: "Zheng-Tian Lu Physics Division, Argonne National Laboratory"— Presentation transcript:

1 JLab FEL – Opportunity for a New Generation of Ultrasensitive Trace Analyzer of Noble Gas Isotopes
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

2 Atmospheric isotopic abundance
Nobel Gas Tracers Half-life Atmospheric isotopic abundance Sources 85Kr 10.8 yr 2x10-11 Nuclear fuel reprocessing 39Ar 269 yr 8x10-16 Cosmic-ray induced reaction 81Kr 229,000 yr 6x10-13 2

3 Radio-Krypton Dating 81Kr (t1/2 = 230kyr, I.A.= 6 x 10-13) Cosmic p, n
83Kr, 82Kr... 81Kr Cosmic p, n 81Kr (t1/2 = 230kyr, I.A.= 6 x 10-13) Polar Ice as a natural archive temperature precipitation gas composition volcanic eruption solar variability... Number of 81Kr atoms in 1 liter of : Air  20,000 Water  1,000 Ice  1,000

4 Accelerator Mass Spectrometry of Kr-81
W. Kutschera et al., NIM B29, 241 (1994); P. Collon et al., NIM B123, 122 (1997) Full stripping at high energy (~ 4 GeV) for isobar separation: 81Kr36+ vs. 81Br35+. National Superconducting Cyclotron Laboratory Michigan State University First 81Kr dating: groundwater in GAB -- P. Collon et al., EPSL 182, 103 (2000)

5 Methods of Trace-Isotope Analysis at PPT Level
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) AMS Muller, Physics Today ATTA

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

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

8 Atom Trap Trace Analysis of Krypton
Ground-level Metastable t » 40 sec 811 nm 10 eV electron collision Discharge Source Transverse Cooling Beam Chopper 2D Focusing Zeeman Slower MOT CCD Camera

9 Single Atom Detection <Single atom signal> = 1600 counts
<Background> = 340  30 counts

10 Counting 81Kr and 85Kr

11 One Million Years of Nubian Aquifer Groundwater History
Groundwater at six sites dated; Flow direction and speed measured; Source determined. 333±44 kyr 212±42 kyr 391±46 kyr 488±45 kyr 678±75 kyr Uweinat Uplift Sturchio et al., Geophys. Res. Lett. (2004)

12 81Kr Dating: From Dream to Practice
Polar Ice Groundwater 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1 Efficiency 107 106 105 104 103 102 10 Water or Ice Sample Size (L) LLC 1969 ATTA-1 1999 AMS 1997 ATTA-2 2003 ATTA-3 2011 ATTA-4 JLab FEL Present Status of ATTA-3: Selectivity requirement: Done; Efficiency requirements: Practical, but far from perfection 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)

13 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]02 4p6 Ground Metastable 5p[3/2]2 124 nm 5s[3/2]01 819 nm Advantages over the existing RF discharge method: Improve efficiency Metastable production efficiency Collimate atomic beam Reduce sample loss and contamination 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 ATTA Team Argonne Atom Trappers
Kevin Bailey Wei Jiang Zheng-Tian Lu Peter Mueller Tom O’Connor Will Williams Argonne Atom Trappers 14

15 Collaborators Neil C. Sturchio University of Illinois at Chicago
Andrew M. Davis University of Chicago L. Young & R. Dunford Chemistry Division, Argonne Shuiming Hu University of Science & Technology of China B. Mack Kennedy Lawrence Berkeley National Lab Roland Purtschert University of Bern Charles Sukenik Old Dominion University

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