Applications of

Accelerator Mass Spectrometry

Walter KutscheraVienna Environmental Research Accelerator (VERA)

Faculty of Physics – Isotope Research and Nuclear PhysicsUniversity of Vienna, Austria

Yerevan Physics Institute, Armenia18 October 2013

Applications of Accelerator Mass Spectrometry (AMS)are based on the measurement of long-lived radionuclidesby counting atoms rather than the radioactive decays.

This allows one to measure radionuclide concentrations in the range from 10-12 to 10-16.

1981

7 radionuclides

10Be, 14C, 26Al, 32Si, 36Cl, 41Ca, 59Ni

2008

+ 17 more

The World of Radionuclides The World of Radionuclides (W.K. Nucl. Instr. Meth B 50 (1990) 252-261)(W.K. Nucl. Instr. Meth B 50 (1990) 252-261)

~140 radionuclides with T1/2 > 1 yr

1996

+9 more

1981

7 radionuclides

10Be, 14C, 26Al, 32Si, 36Cl, 41Ca, 59Ni

2008

+ 17 more

The World of Radionuclides The World of Radionuclides (W.K. Nucl. Instr. Meth B 50 (1990) 252-261)(W.K. Nucl. Instr. Meth B 50 (1990) 252-261)

~140 radionuclides with T1/2 > 1 yr

1996

+9 more

2013

+22more

total of

55

radionuclides

Accelerator Mass Spectrometry (AMS) for “all“ isotopes: 10Be, 14C, 26Al, 36Cl, 41Ca, 55Fe, 129I, 182Hf, 210Pb, 210Bi, 236U, 293-244Pu, SHE, (H2)–, (43Ca19F4)– –, PIXE-ART, Nucl. reactions: 6,7Li

Negative-Ion Sources

Negative- Ion Mass Spectro-meter(keV)

Positive-Ion MassSpectro-Meter(MeV)

Stripping and Molecule Dissociation

Detector area

1996: 1st operation 2001: 1st upgrade2007: 2nd upgrade

3 MV, 200 m2

500 kV, 30 m2

200 kV, 7 m2

The minaturisation ofAMS facilitiesM. Suter, H.-A. Synal et al., ETH/PSI Zürich

Figure from W.K., Int. J. Mass Spectrom. 242 (2005) 145

Bio-MICADAS (Mini Carbon Dating System)Vitalea Science, Davis CA, USA

2.5 m

3.0 m

Progress in carbon sample size and precision

Method Sample mass Precision Age uncertainty (g carbon) (% of 14C/12C) (years)

Beta counting 1 – 5 0.2 16(1950)

AMS (0.1 – 1)x10-3 0.3 25(1980)

AMS (2 – 5)x10-6 1 82 (2) (2010)

The seven domains of the environment

Atmosphere(cosmic-ray interaction, trace gases)

Biosphere (plants, animal,humans)

Hydrosphere (oceans, lakes, rivers, groundwater)

Cryosphere (polar ice sheets, glaciers)

Lithosphere(rocks, soil, sediments)

Cosmosphere(meteorites, lunar material)

Technosphere(man-made materials and radionuclides)

Overview of research areas and the corresponding radionuclides, which are used with AMS in the seven domains of our environment at large

(underlined radionuclides are man-made, [ ] means not yet feasible at natural abundance)

Domain Research area Radionuclide

Atmosphere Production of radionuclides by cosmic-ray interaction 10Be, 14C, 26Al, 32Si, 36Cl, 39Ar, 81Kr, 129I

Chemistry and dynamics of CO,CO2, CH4 14C, 14C Mixing of stratospheric and tropospheric air 14C, 10Be

Releases from nuclear industry 14C, 99Tc, 129I

Fossil fuel effect, ‘dead‘ CO2 14C

Bomb peak from nuclear weapons testing 14C

Biosphere Radiocarbon dating in archaeology and other fields 14C

Radiocarbon calibration (tree rings, corals,sediments,…) 14C

Development of radiocalcium dating of bones 41Ca

Bomb peak dating (forensic medicin, human DNA) 14C

Microdosing for drug developent in the pharma industry 14C

In vivo tracer studies in plants, animals, humans 14C, 26Al, 41Ca

Hydrosphere Dating of groundwater (important freshwater source) 14C, 36Cl, 39Ar, 81Kr, 129I

Global ocean currents 14C, 14C, 39Ar, 99Tc, 129I, 231Pa, 236U

Plaleoclimatic studies in lake and ocean sediments 14C

Cryosphere Paleoclimatic studies in polar ice sheets 10Be, 14C, 26Al, 36Cl, [81Kr]

Paleoclimatic studies in glaciers 14C, 32Si

Tracing solar variability in time (Greenland ice cores) 10Be, 14C, 36Cl

Bomb peak record in recent ice 36Cl, 41Ca, 129I

Domain Research area Radionuclide

Lithosphere Exposure dating of rocks (deglaciation, geomorphology) 10Be, 14C, 26Al, 32Si, 36Cl, 53Mn,

Neutron dosimetry of Hiroshima bomb explosion 36Cl, 41Ca, 63Ni

Neutron flux monitor in in uranium minerals 236U

Paleoclimatic studies in loess 10Be, 14C

Tectonic plate subduction studies 10Be

Cosmosphere Cosmogenic nuclides in meteorites and lunar material 10Be,14C,26Al,36Cl,41Ca,53Mn,59Ni, 60Fe

Live supernova remnants in terrestrial material 26Al, 60Fe, 244Pu, [146Sm, 182Hf, 247Cm]

Stable trace isotopes in solar grains 194,195,196,198Pt

Geochemical solar neutrino detection [99Tc, 205Pb]

Search for superheavy elements in terrestrial material Eka-Th, Ds, Rg, Fl, Eka-Bi (A ~ 300)

Search for exotic particles in Nature free quarks, strange matter, …

Technosphere Half-life measurements of radionuclides 32Si,41Ca,44Ti,60Fe,79Se, 126Sn,146Sm

Depth profiling in fusion wall 3H

Possible fusion plasma thermometer 27Al(n,2n)26Al

Reaction studies for nuclear astrophysics 14N(n,p)14C, 26Mg(p,n)26Al, 40Ca(α,γ)44Ti, 54Fe(n,γ)55Fe

Reaction studies for fission reactors 209Bi(n,g)210mBi, 232Th(,n,3n)230Th, 232Th(n,3n)231Th(ß-)231Pa

Nuclear safeguards 146Sm, 149Sm, 151Sm, 233U, 236U, 237Np, 239, 240, 241, 242, 244Pu

A basic problem in 14C dating is

that an absolute age can only be obtained

from the measured 14C/12C ratio

if one knows the initial 14C/12C ratio

12 April 2007Age determinations by radiocarbon content: Checks with samples of known age

J. R. Arnold and W. F. Libby, Science 110 (1949) 678-680

14CO

14Ct = 14CO e-t

Dendrochronology: Establishing an absolute time scale from overlapping tree ring patterns(Figure from E.M. Wild and W.K., Spektrum der Wissenschaft, Dec. 2011, p.48)

12,000 10,000 7500 5000 2500 0 Years before present

Reference value: 14C/12C = 1.2x10-12

Variation of the 14C content in tree rings

of known ageFigure from P.J. Reimer et al., Radiocarbon 46

(2004) 1024

14C Dating and the Iceman “Ötzi“

Discovery of Ötzi

The European Alps

Italy

Austria

Germany

France

Switzerland

Slowenia

Slowakia

Czech Republic

Hans Kammerlander and Reinhold Messner, two famous mountaineers from South Tirol, view Ötzi on 21 September 1991, two days after his discovery

(Figure from W.K., W. Müller, Nucl. Instrum. Meth. B 204 (2003) 705)

Bow

14C dating of bone and tissuefrom the Iceman Ötzi at theAMS labs of Oxford and Zürich in 1992

Uncalibrated (radiocarbon) age:4550 ± 19 yr BP (before present)

Calibrated age range:5300 to 5050 BP

(Figure from W.K., W. Müller, Nucl. Instrum. Meth. B 40 (2003) 705)

14C dating at VERA of various materials found at theDiscovery site of the Iceman Ötzi, matching the date of the Iceman.

(Figure from W. K., W. Müller, Nucl. Instrum. Meth. B 204 (2003) 705)

14C dating at VERA of various materials found at the discovery site of the Iceman Ötzi, not matching the date of the Iceman.

(Figure from W. K., W. Müller, Nucl. Instrum. Meth. B 204 (2003) 705)

14N + n 14C + p

14CO2

Biosphäre(t1/2 = 5700 Jahre)

Simplified picture of the main ocean currents transporting heat around the globeIllustration by Wally Broecker from the Lamont Doherty Earth Observatory, Columbia University, New

York

The Ugly and the Beautiful:

14C Bomb Peak Dating of Human DNA

14N → 14C + p

Cosmic rays (p)

Atmosphere (N, O, Ar)

n

n

14CO2

O2

Plants + Oceans(14C)

Biosphere (14C)

14C production through cosmic rays and nuclear weapons testing

Natural 14C variations

14C Bomb Peak

Variation of the 14C content in atmospheric CO2 during the last 4000 Years [Spalding et al., Cell 122 (2005) 133]

Natural 14C level

NTBT 1963

14C decay (t1/2 = 5700 a)

Long-term observations of 14C in atmospheric CO2 in the northern and in the southern hemisphere

Levin and Hesshaimer, Univ. Heidelberg, Radiocarbon 42/1 (2000) 69

Retrospective Birth Dating of Cells in Humans

Kirsty L. Spalding et al.

Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm

Cell, Vol. 122 (15 July 2005) 133-143

14C in genomic DNA reflects the age of cells 

“Most molecules in a cell are in constant flux, with the unique exception of genomic DNA, which is not exchanged after a cell has

gone through its last division.

The level of 14C integrated into genomic DNA should thus reflect the level in the atmosphere at any given point, and we hypothesized that

determination of 14C levels in genomic DNA could be used to

retrospectively establish the birth date of cells in the human body.”  

K.L. Spalding et al., Cell 122 (15 July 2005) 133-143

Some facts about human DNA and 14C(A physicist’s view)

Basic composition of DNA: Macromolecule with 3x109 basepairs

Chem. sum formula per bp: C20H23N7O13P2 and C19H22N8O13P2

Molecular weight: ~630 daltons per base pair, total ~1.9x1012 Da

Mass of DNA per cell: 2 DNA per cell = 2 x 3 pg = 6 pg

Mass of carbon (40 wt% C): 2.4 pg

Totel length of DNA per cell: 2 x 3x109 x (0.34 nm) = 2 m

C atoms of DNA per cell: 2 x 3x109 x (20 C) = 1.2x1011 C atoms14C/12C: 1.2x10-12 

DNA of 10 cells: ~1 14C atom

15 million cells: 1.5 million 14C atoms

C from DNA of 15 million cells: ~36 µg C

Total 14C detection efficiency: ~2% ~ 30,000 14C atoms detected  

Birth

14C dates from DNA extracted from the respective cellsSpalding et al., Cell 122 (2005) 133

Cortical neurons and non-neuronal cells have different renewel ratesSpalding et al., Cell 122 (2005) 133

birth

birthbirth

birth

birth

Determination of the age of neocortical neuronsBhardwaj et al., PNAS 103 (2006) 12564

The human olfactory bulb project

Jakob LieblVERA, Vienna

Kirsty SpaldingKarolinska,Stockholm

Peter Steier VERA, Vienna

Olaf BergmannKarolinska, Stockholm

The technical challenge for the olfactory bulb projectOnly 2 to 5 µg carbon from DNA extracted from olfactory bulb cells were available. This is almost

thousand times less than for standard 14C dating (~1 mg C). Therefore 14C AMS for µg-carbon samples had to be developed at VERA. The key task was the reduction of carbon background in

every step from human sample taking to the 14C measurement.

Turnover of non-neuronal cells

Limited production of neuronal cells after birth

Bergman et al., The Age of Olfactory Bulb Neurons in Humans, Neuron 74 (2012) 634-639

Δ1

4C

(‰

)

Evidence for neurogenesis in the hippocampus (memory, learning, emotion) of adult humans from 14C measurements in neuronal DNA of 57 individuals

Kirsty L. Spalding et al., Cell 153 (2013) 1219-1227

Birt

h da

te o

f ind

ivid

ual

The search for superheavy nuclides in Nature

Island of superheavy elements (SHE)

Gregory N. Flerov (1913-1990)

 Early History of Superheavy Elements (SHE)  In the late 1960s, shell model corrections of the liquid drop model led to a region of

stability for superheavy elements: Myers & Swiatecky, Nilsson, Strutinsky, Nix, Möller, ....

Sea of instabilty

Upper end of the chart of Nuclides (Stoyer, Nature 442 (2006) 876

SuperheavyElements?

34 s

11 s

2.6 s

0.06s

14N + n 14C + p

14CO2

Biosphäre(t1/2 = 5700 Jahre)

Extension of the periodic table of elements beyond element 103 by Glenn Seaborg (1969)

How to search for superheavy elements in nature

Modified picture from: M. Stoyer, Nature 442

(2006) 876.

292Eka-ThSearch for SHE nuclides in Nature

Positive evidence from ICP-SF-MS:Marinov et al., Jerusalem, 2007, 2009, 2010

Upper limits from AMS:Lachner et al., Munich, 2008

Dellinger et al., VERA, 2010, 2011Ludwig et al., Munich 2012

Search for SHE nuclides in Nature

Positive evidence from ICP-SF-MS:Marinov et al., Jerusalem, 2007, 2009, 2010

Upper limits from AMS:Lachner et al., Munich, 2008

Dellinger et al., VERA, 2010, 2011Ludwig et al., Munich 2012

< 5 × 10-13

< 6 × 10-14

< 7 × 10-16

< 2 × 10-15

< 4 × 10-15

< 3 × 10-16

(1-10) × 10-10

~ 1 × 10-12

211,213,217,218Th: (1-10) x 10-11, <8 x 10-15211,213,217,218Th: (1-10) x 10-11, <8 x 10-15

Conclusion

Accelerator Mass Spectromtry in general

• AMS is one of the most powerfull analytical tools to study our environment at large.

14C bomb peak dating of human DNA

• This method shows great promise to study neurogenesis in the human brain.

• Other parts of the human body have been studied as well (e.g.heart, fat cells).

Search for superheavy nuclides in Nature

• Is the absence of evidence, evidence of absence?

• Answers to this question can only be approached by improved measurements and improved theoretical predictions (e.g. nuclear astrophysics, atomic physics, chemistry, half-lives)