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

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