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Zheng-Tian LuPhysics Division, Argonne National LaboratoryDepartment of Physics, University of Chicago
Supported byDepartment of Energy, Office of Nuclear Physics
National Science Foundation, Earth Science Division
JLab FEL – Opportunity for a New Generation of JLab FEL – Opportunity for a New Generation of
Ultrasensitive Trace Analyzer of Noble Gas Ultrasensitive Trace Analyzer of Noble Gas
IsotopesIsotopes
Nobel Gas TracersNobel Gas Tracers
Half-life
Atmospheric isotopic abundance
Sources
85Kr 10.8 yr 2x10-11 Nuclear fuel reprocessing39Ar 269 yr 8x10-16 Cosmic-ray induced
reaction81Kr 229,000
yr
6x10-13 Cosmic-ray induced reaction
• 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
83Kr, 82Kr...
81Kr
Cosmicp, n
81Kr
Radio-Krypton DatingRadio-Krypton Dating81Kr ((t1/2 = 230kyr, I.A.= 6 x 10-13)
National Superconducting Cyclotron Laboratory
Michigan State University
Full stripping at high energy (~ 4 GeV) for isobar separation: 81Kr36+ vs. 81Br35+.
Accelerator Mass Spectrometry of Kr-81Accelerator Mass Spectrometry of Kr-81W. Kutschera et al., NIM B29, 241 (1994); P. Collon et al., NIM B123, 122 (1997)
First 81Kr dating: groundwater in GAB-- P. Collon et al., EPSL 182, 103 (2000)
Methods of Trace-Isotope Analysis at PPT LevelMethods 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)
Neutral Atom TrapSodium, NIST
Laser Trapping and Cooling - a quick primer
"for development of methods to cool and trap atoms with laser light"
Steve Chu ClaudeCohen-Tannoudji
William Phillips
1997 Nobel Physics Laureates
Discharge
Source
TransverseCooling
BeamChopper
2DFocusing
ZeemanSlower
MOT
CCDCamera
Atom Trap Trace Analysis of KryptonAtom Trap Trace Analysis of Krypton
5p[5/2]3
5s[3/2]2
4p6Ground-level
Metastable 40 sec
811 nm
10 eVelectron collision
0.0 0.5 1.0 1.5 2.0 2.5
0
5
10
15
20
25
Background
One Atom 81Kr
Photon S
cattering R
ate (
kH
z)
Time (sec)
<Single atom signal> = 1600 counts<Background> = 340 30 counts
0 1 2 3 4 5
0
5
10
15
2081
Kr
Photo
n S
catt
. R
ate
(kH
z)
Time (min.)
0 5 10 15 20 25
0
5
10
15
20
25
One Atom
Background
83Kr
Flu
orescence (
kH
z)
Time (sec)
Single Atom DetectionSingle Atom Detection
-1000 -800 -600 -400 -200 0 2000.0
0.1
0.2
0.3
84Kr
81Kr85Kr
86Kr82Kr
78Kr
80Kr83Kr
T
rap F
luo. (arb. unit)
0.0
0.2
0.4
0.6
0.8
1.0
83Kr
Trap F
luo.(
arb. units)
-150 -120 -90 -60 -30 0 30 60 90
05
101520253035
(0.5 hrs.)
85Kr
81Kr (3 hrs.)
Atom
Counts
Frequency Offset (MHz)
Counting Counting 8181Kr and Kr and 8585KrKr
One Million Years of Nubian Aquifer Groundwater One Million Years of Nubian Aquifer Groundwater HistoryHistory
Sturchio et al., Geophys. Res. Lett. (2004)
• Groundwater at six sites dated;• Flow direction and speed measured;• Source determined.
Uweinat Uplift
33344 kyr
21242 kyr
39146 kyr
48845 kyr
67875 kyr
0.60.21.0 Myr
8181Kr Dating: From Dream to Kr Dating: From Dream to PracticePractice
10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1Efficiency
107 106 105 104 103 102 10 1
Water or IceSample Size (L)
Groundwater
Polar Ice
LLC1969
AMS1997
ATTA-11999
ATTA-22003
ATTA-32011
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-4JLab FEL
Present Status of ATTA-3:
• Selectivity requirement: Done;
• Efficiency requirements: Practical, but far from perfection
Advantages over the existing RF discharge method:•Improve efficiency
• Metastable production efficiency• Collimate atomic beam
•Reduce sample loss and contamination
ATTA-4 with JLab FELATTA-4 with JLab FEL
Optical production of Kr* via two-photon excitation: 124 nm + 819 nm
Young et al., J. Phys. B (2002)Ding et al. RSI (2007) 5s[3/2]0
2
4p6
Ground
Metastable
5p[3/2]2
124 nm
5s[3/2]01
819 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)
Kevin BaileyWei Jiang
Zheng-Tian LuPeter MuellerTom O’ConnorWill Williams
Argonne Atom Argonne Atom TrappersTrappers
ATTA TeamATTA Team
CollaboratorsCollaborators
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