Series of Lectures at Kyoto University, Professor Ide’sLaboratory Supervised and Chaired By Professor Soey SieLaboratory Supervised and Chaired By Professor Soey SieDuring his Visit to Kyoto University 2003

2003年 京都大学井手研究室で行われた加速器質量分2003年、京都大学井手研究室で行われた加速器質量分

析の記録。加速器質量分析は、文化財研究における年代測定 様々な分野での超微量元素分析にきわめて重要な

Harnessing AMS

測定、様々な分野での超微量元素分析にきわめて重要な分析手法である。

g

AMS: 25 years of a revolutionary form ofAMS: 25 years of a revolutionary form of mass spectrometry

Series of Lectures In Kyoto University, Professor Ide’s LaboratorySupervised and Chaired By Professor Soey Sie During his visit to p y y gKyoto University 20042004年、京都大学井手研究室で行われた加速器質量分析の記

H i AMS

録。加速器質量分析は、文化財研究における年代測定、様々な分野での超微量元素う分析にきわめて重要な分析手法である。

Harnessing AMS

AMS: 25 years of a revolutionary form of mass spectrometrymass spectrometry

Soey SieSoey SieIIC-Kyoto University and CSIRO, Sydney

Harnessing AMSHarnessing AMS

AMS- Accelerator Mass Spectrometry has progressedAMS Accelerator Mass Spectrometry has progressed beyond experimentation, and has produced novel and unique results in many areas of applications. It is now

timely to extend the applications beyond research institutions and develop applications of benefit to

much wider sections of the communitymuch wider sections of the community.

The lecture series aims:

Review the state-of-the-art of AMS:Cosmogenic Radiocarbon AMSCosmogenic Radiocarbon AMS

Other Cosmogenic Isotopes AMSHeavy Isotopes AMSy p

Non-cosmogenic Isotopes AMSBiomedical Application: Future of AMS?

Speakers:Prof T Nakamura (Nagoya)Prof. T. Nakamura (Nagoya)Prof. K. Kobayashi (Tokyo)Prof. M. Nakamura (Kyoto)( y )

Prof. A. Ide-Ektessabi (Kyoto)

This lecture outline:

Brief background history of AMSPrinciple of AMSPrinciple of AMS

Some technical aspectsCosmogenic Radionuclidesg

Radiocarbon AMSExamples of applications

f S?Biomedical Application: Future of AMS?

Historical PerspectiveHistorical Perspective

1977: McMaster University (Nelson et al.) and U. Rochester (Purser, Gove, Litherland) groups demonstrated the detection of radiocarbon directly by accelerating the ions to MeV energies in a tandem electrostatic accelerator.

Acceleration to MeV energies enabled detection of the isotope clear of interfering molecules (12CH2

13CH)clear of interfering molecules ( CH2, CH)

The tandem accelerator method gained more following because of the relative ease of method and being more versatile: 10Be 36Clthe relative ease of method and being more versatile: 10Be, 36Cl.

Key features of AMS:Ult hi h iti it 10 15 b d iti it IUltra high sensitivity : 10-15 abundance sensitivity. In conventional mass spectrometry, it is not feasible to detect better than 10-6 due to practical limitations of mass resolution.The sensitivity reduces the amount of sample material required for the analysis.

Principles of AMS:

negative ion production by sputtering using Cs+ ions. Possible g p y p g gisobaric suppression. First stage analysis: electric (E/q) and magnetic analysis (m/q), q=1.ions accelerated to MeV energies in a tandem electrostatic gaccelerator.Negative ions are stripped of electrons and converted to positive ions. This leads to destruction of molecular ions.lack of molecular interference: lower mass resolution required, more efficiency. 2nd magnetic (m/q) and electrostatic analysis(E/q).Detection of ions at MeV energies enables further isobaric interferences resolution exploiting the stopping power (dE/dx) dependence on atomic number Z and mass number A.

double mass spectrometry: low energy/high energy.electric and magnetic analyses increase sensitivity.abundance sensitivity: 10-15 achievable.

Accelerator Mass SpectrometryAccelerator Mass Spectrometry

lLow Energy High Energy

sample

acceleratorinjectormagnet

analysingmagnet

mass spectrometer mass spectrometer

samplemagnet

negative stripper canal

gm/q analysis

Cs gun

gsecondaryions

electrostaticanalyserE/q analysis

molecular ions

sample

Cs+ beamq y

molecular ionsdestruction in the

stripper canalelectrostaticl sample

iondetectormolecular atomic

analyser

molecularnegative ions

atomicpositive ions

Secondary Ion Beam Mass Spectrum (C)Secondary Ion Beam Mass Spectrum (C)

10 112 C- 13 C- 1·10 -2 Magnetic analysis of cesium

10 -2

10 -1

10 0 12 CH- 3·10 -2

13 CH- 3·10 -4

12 CH2- 3·10 -4

14 NH-

13

Magnetic analysis of cesium sputtered C- ions.Each mass peak has a long “tail” d t th t l

10 -5

10 -4

10 -313 CH2

- due to the natural energy distribution in the sputtering process.

8

10 -7

10 -6

10

Ion

Curre

nt “tails” prevent simple mass spectrometry from achieving high sensitivity. Electric analysis helps

“tail”

10 -10

10 -9

10 -8 sensitivity. Electric analysis helps to reduce the tail.Each peak has severe molecular interferences

10 -13

10 -12

10 -11

Contemporary 14 C

19000 Years

interferences.Selective ion production e.g. 14N-

yield is very small, there is no 10 -14

1514131211

Mass Number [for a given Energy]

isobar problem.

Low Energy Mass spectrometerLow Energy Mass spectrometer

I i j i h dIsotope injection methods:

Main method: Sequential isotope injection by

Varying the magnetic field - slow, affects precision

Modulating the beam energy – ‘bouncing’

Mainly C system: Recombinator method: all isotopes analyzed magnetically first then recombined。

Low Energy: Sequential InjectionLow Energy: Sequential Injection

Bouncing SystemInsulate magnet beam box and apply modulating voltage.

Bouncing System

g gAllows fast mass change: less than 50µs typical.Mass variation easily achieved.Faster bouncing results in better precision by reducing the effect of fluctuations in beamfluctuations in beam intensity

Low Energy: Recombinator InjectorLow Energy: Recombinator Injector

“Brown Achromat”Advantage:

Reduce the effect of beam fluctuation.

12C-

13C-

14C-

Disadvantage:Moving parts 12C

attenuatorrequire higher maintenance.Practically limited to C system onlyto C system only.

To acceleratorSource

I j t ll i t i lt l ft tt ti thInjects all isotopes simultaneously after attenuating the most abundant isotope to reduce accelerator loading.

High Energy SystemHigh Energy System

Electrostatic analysis before magnetic analysisMulti-faraday cup for stable isotopes (if using broad range magnet)

Electrostatic analysis after magnetic

magnet). Ion-counter for rare-isotope.

Electrostatic analysis after magneticenergy modulation not practical.Use high energy “bouncer”: deflector plates at entrance and exit ofplates at entrance and exit of magnet.

mass change in less than 50µsmass range > ±7%mass range > ±7%easy mass variation

Faraday cup for abundant isotopes and ion counter for rare isotopeand ion counter for rare isotope.

Low Energy Mass spectrometer (CSIRO)Low Energy Mass spectrometer (CSIRO)

ElectrostaticElectrostatic analyzer before magnet: energy filtfilter.Sequential injection by “bouncing”.y gMicrobeam Cs+

High Energy Mass spectrometer (CSIRO)High Energy Mass spectrometer (CSIRO)

electrostatic analyzer after the magnet.High energy fastHigh energy fast “bouncer” system (< 1ms switching).SSynchronized low energy and high energy bouncer system.

Gas Ion CounterGas Ion Counter

measures energy loss

Segmentedanode

Δ E1 Δ E2 Eresthin window(mylar)

ions

anode

grid

cathode

Gas- e.g. isobutane

Energy loss information is used

t t i f diff t ito separate ions of different species

2D Spectrum from a Gas Detector2D Spectrum from a Gas Detector

Isotop yB

simulation

Isotop xA

²Ene

rgy Isotop y

A

Isotop zA

Energy Gate

²E Gate

gy

Final Energy

AMS CommunityAMS Community

AMS conferences:1978: Rochester

Other AMS forums:IBA (since 1981)D t (1982)1978: Rochester

1981: (Niagara)1984: Zurich1987 T t

Denton (1982)AGU (mid 80’s)Goldschmidt (90’s)

1987: Toronto1990: Paris1993: Canberra/Sydney Multi-disciplinary team:1996: Tucson1999: Vienna2002: Nagoya

PhysicistsChemistsGeologistsg yArcheologistsBiologists (Medicine)

AMS Facilities

AMS facilities(2002)

AMS Facilities

AMS facilities(2002)

20

25

USA/Canada

10

15

20 USA/CanadaEuropeJapanE.Asia

0

5

10OceaniaRest of World

01st gen 2nd gen 3rd gen 4th gen total(63)

1st generation: developed from large existing accelerator1st generation: developed from large existing accelerator 2nd generation: purpose built General Ionex system. 3rd generation: recombinator C AMS system, NEC system, other purpose built system p p y4th generation: small (<1MV) machines

Trends in AMS system developmentTrends in AMS system development

1978-1983 Conversion of older generation tandem Van de Graaff gaccelerators (EN- 6 MV, FN-8 MV) and experimental systems with higher terminal voltages. Larger machines are suitable for the heavier cosmogenic isotopes (Rochester, Saclay, Zurich, Aarhus,heavier cosmogenic isotopes (Rochester, Saclay, Zurich, Aarhus, Utrecht, Oxford, Kyoto, Kyushu, Beijing, Shanghai, Munich, Erlangen, Tsukuba).

1982-1988: first generation of purpose built AMS system based on 98 988 s ge e a o o pu pose bu S sys e based oa new type of accelerator produced by General Ionex: Tandetron (3 MV).- 6 were built: Oxford, Arizona, Toronto, Nagoya, Gif-sur-Yvette Sydney(North Ryde)Yvette, Sydney(North Ryde).

Trends in AMS system developmentTrends in AMS system development

1988-1993: development of simultaneous injector system for C j ymachines (recombinator). General Ionex taken over by High Voltage Engineering Europa. 2nd generation Tandetrons based on this principle (Woods Hole, Groningen, Kiel, Nagoya, Mutsu…).this principle (Woods Hole, Groningen, Kiel, Nagoya, Mutsu…). Other purpose built systems include Tokyo.

f S1993-now: patent for AMS ran out and competing companies start to build AMS machines (mainly National Electrostatic Company of the US): Vienna, Tsukuba (NIES), Livermore, Tono.

1990-now; Microbeam AMS development for trace elements (Denton Toronto Sydney North Ryde NRL Washington)(Denton, Toronto, Sydney-North Ryde, NRL Washington).

Trends in AMS system developmentTrends in AMS system development

1998-now: development of small (radiocarbon) AMS system (<1 ( ) y (MV): NEC (Zurich, Athens-Georgia), HVEE, Newton Scientific.

Typical sample throughput: > 8000 samples/year SampleTypical sample throughput: > 8000 samples/year. Sample preparation is usually the bottleneck. Typical cost/sample $300-500 US- less for large batches.

New trend: dedicated, semi- or fully commercial service facilities, for example:example:

NOSAMS- oceanographyYork – pharmaceutical industry

1st generation AMS (early): 6MV AMS at ETH Zurich (1979)

1st generation (later): 8MV AMS at Purdue University:

1st generation (later): 10MV AMS at Livermore:

2nd generation: 3MV AMS at Isotrace (Toronto)

General Ionex:OxfordArizonaTorontoNagoyaGif Y ttGif-sur-YvetteSydney

3rd generation: 3MV AMS at WoodsHole

Woods HoleWoods HoleGroningenKiel

NEC machines

R bi tRecombinator

4th generation: 500 kV AMS at ETH Zurich

Z i hZurichGeorgia

4th generation: 800 kV AMS Newton Scientific/MIT

Cosmogenic IsotopesCosmogenic Isotopes

Produced mainly by spallation reaction of cosmic rays (mainly y y y ( yenergetic protons) with atmosphere.

Of interest to AMS are mainly rare long lived isotopes because ofOf interest to AMS are mainly rare, long lived isotopes because of the difficulty in detection using beta decay counting.

Some are produced in-situ on the earth’s surface (10Be, 26Al, 36Cl, 41Ca).

Atmospherically produced isotopes have residential and mixing time in atmosphere about 1 year, before entering the biosphere through assimilation and terrestrial reservoirs through precipitation.

Abundance of some (14C 36Cl) modulated by atmospheric nuclearAbundance of some (14C,36Cl) modulated by atmospheric nuclear test (“Bomb pulse”) and by nuclear power industry (36Cl,129I).

Cosmogenic IsotopesCosmogenic Isotopes

Isotope Half-life (years) Typical reservoir

10Be 1.51x106 Sediments, hydrosphere*, y p

14C 5730 Biological, atmosphere,HydrosphereHydrosphere

26Al 7.17x105 Terrestrial

36 536Cl 3.01x105 Hydrosphere, terrestrial

41Ca 1.03x105 Biological, terrestrial, sediments

129I 1.57x107 Hydrosphere

* - hydrosphere includes snow, ice

AMS-9 Conference NagoyaAMS-9 papers

3540

5101520253035

OthersJapan

05

spheric

onmentheologyograp

hyyd

rology

phologyac

iologyhemist

ryfeguardynucle

imedica

l

Atmosp

EnviroArch

eOce

anog

HydGeomorp

hGlac

Cosmoch

e

Nuclear

safe

Heavy

Biom

All papers(173)

Atmospheric

Environment

Archeology

Oceanography

Hydrology

GeomorphologyGeomorphology

Glaciology

Cosmochemistry

Nuclear safeguard

Heavy nuclei

Biomedical

AMS-9 Conference Nagoya

14C: archeology, environment, atmospheric, oceanography, gy p g p ybiology….

10Be,26Al: geomorphology (erosion, exposure ages), environment36Cl: hydrology, environment

Other isotopes: hydrology, environment (129I), nuclear safeguard,

AMS Applications(174)AMS9-2002

geology, geochronology, biology

14C10Be/26Al

36ClOther Iso.

Other Isotopes applicationsOther Isotopes applications

10B t di f ( t it i ) d i10Be: studies of exposure ages (meteorites, moraines) and erosion transport (sediments, alluvial and aeolian)

26Al: usually used in combination with 10Be in exposure ages.

36Cl: hydrological studies, plumes from nuclear power plant, exposure studies.

129I: hydrology, pollution from nuclear reprocessing plants. Famous cases include contamination from Sellafield and Le Havre

i l t S i t l b i i th B treprocessing plants, Soviet nuclear submarine grave in the Barentz sea.

Radiocarbon: 14C (T : 5730 yr)Radiocarbon: 14C (T1/2: 5730 yr)

Residential and mixing time in atmosphere about 1 year, before entering the biosphere through photosynthesis.

Intensity modulated by 11 year solar activities (sun spots- throughIntensity modulated by 11 year solar activities (sun spots through effect on the magnetosphere) and recently by atmospheric nuclear test (“Bomb pulse”).

C ti l th d t t d bConventional methods started by Libby using beta counting, requiresat least 10 grams of carbon. Withsmall liq id scintillator co ntingsmall liquid scintillator countingmethod, about 1 gram is required.With AMS, as little as 200 microgramcan be datedcan be dated.

Primary calibration through tree ringsstudiesstudies.

Radiocarbon: 14C (T : 5730 yr)Radiocarbon: 14C (T1/2: 5730 yr)

St d di d t PDB C t B l it f th P DStandardized to PDB – Cretaceous Belemnite from the Pee Dee formation in South Carolina, to take into account fractionation due to biological and other processes.

State-of-the-art precision is about 0.3%, corresponding to 20 years in 400 year old sample but 200 years for 2500 yr old sample due toin 400 year old sample but 200 years for 2500 yr old sample due to uncertainty in 14C production rate.

The oldest date accessible is around 0.3 pMC (percent modern carbon) corresponding to 55 ky. Limit is due to possible ion source contamination sample preparation machine instabilitiescontamination, sample preparation, machine instabilities.

Radiocarbon dating: calibrationRadiocarbon dating: calibration

Uncertainty is mainly due non-constant 14C production and uncertainty inhalf life. Reliable calibration is made against tree rings.

Trends in carbon sample preparationTrends in carbon sample preparation

1978-83: intensive development in graphitization methods. Ni, Fe, gCo used in reducing CO2 to graphite.

1983 88: 1mg C sample was typical Now samples < 0 1 mg is1983-88: 1mg C sample was typical. Now samples < 0.1 mg is possible.

1988-93: development of gas sources. CO2 fed into the ion source directly. Problems: inefficiency in producing C- ions, memory effect (contamination of the source) technical problem in introducing(contamination of the source), technical problem in introducing small quantities of gas efficiently.

State of the art: extraction of sufficient sample from about 1 liter of water (vs. 100’s liters), less than 1 kg of firn (compacted snow) or ice (vs. 20 kg previously).( g p y)

Example of C sample preparation for AMS:Purdue University

sample

Gas line for natural radiocarbon sample preparation

Typical sample requirement for radiocarbonTypical sample requirement for radiocarbon

M t i l Q tit M t i l Q titMaterial Quantity Material Quantity

Wood (a) 20 – 30 mg Shell, Carbonates 20 – 30 mgWood 20 30 mg Shell, Carbonates 20 30 mg

Bone (teeth, tusk, ivory) (b) 1 – 2 g Paper, textiles 20 – 30 mgivory) ( )

Charcoal 10 – 50 mg Grass, seeds, leaves, grains 20 – 40 mg

Water 0.5 – 1 litre Hair, skin 10 – 20 mg

(a) - If alpha-cellulose is required for dating, 50 – 100 mg of wood are necessary.If alpha cellulose is required for dating, 50 100 mg of wood are necessary.(b) - The sample size depends on the state of preservation.

Typical sample requirement for 10Be/26AlTypical sample requirement for 10Be/26Al

Material Minimum tit

Typical titquantity quantity

Ice, snow or rain for 10Be 500 g 1 kg

Quartz bearing rock for 10Be or 26Al 50 g 500 g

Sieved & etched quartz for 10Be or 26Al 10 g 200 g

BeO target mass 0.5 mg 1.5 mg

Al2O3 target mass 0.5 mg 3 mg2 3 g g g

Trends in Ion Source DevelopmentTrends in Ion Source Development

L i i f C b d ti F it (f i t d WLarger ionizer for more Cs+ beam production. Frit (from sintered W powder) replaced by large surface hemisperical ionizer. Frit based ionizers are still used for small samples.

Development of gas source – CO2 directly ionized for C- still using Cs as electron sourceCs as electron source.

Automated multi-sample loader for higher throughput.p g g p

Development of a microbeam source.

Multi target Ion Source: increased automationMulti-target Ion Source: increased automation

To accelerator

Sample mountSample mount

Sample “wheel” accommodates 134 samples

Sample (graphite)

Sample wheel accommodates 134 samples

Examples of notable cases in radiocarbon AMSExamples of notable cases in radiocarbon AMS

Sh d f T i d ibl b f l lShroud of Turin: made possible because of low sample requirements- a few cm of thread.

Art /archeological objects: sampling does not cause visible damage

Oceanic Circulation studies: made possible due to low sampling requirement, e.g. 1 litre of water contains sufficient C for analysis.

Polar Ice Cores: similar case, less than 1 kg of sample is sufficient resulting in higher time resolution.

Shroud of TurinShroud of Turin

Venerated relic believed to be the burial shroud of Jesus

Dating of the Shroud of Turin (1989)Dating of the Shroud of Turin (1989)

A ti f O f d Z i h R h t d A i tA consortium of Oxford, Zurich, Rochester and Arizona got permission to date the Shroud.

Sample consisted of a few threads from the margins of the material.

Sample was dated by AMS to be of 14th century. This is consistent with the style of the object.

Controversy remains with various theories put forward to refute the younger date but none are scientifically viable.

As far as the Catholic church is concerned it is still an open questionquestion

Dating of Aboriginal dwelling and rock artDating of Aboriginal dwelling and rock art

A site in the Kimberley North AustraliaA site in the Kimberley, North Australia was dated by thermoluminescence to be more than 70,000 years old. This h i t t i li ti t th dhas important implication to the under-standing of earliest human settlement of Australia.

Sample was dated by AMS (ANSTO) to be of more recent (35 5 +/ 0 6 ky)be of more recent (35.5 +/- 0.6 ky).

Controversy remains as to the sampling y p gmethod, but the point remains that there is no datable material with anywhere near the previous age estimate.near the previous age estimate.

WOCE programWOCE program

Conducted by Woods Hole yWOCE (World Oceanic Circulation Experiment 1991-2000) involves extensive2000) involves extensive sampling (13000) in the Pacific and Atlantic Oceans.

WOCE programWOCE program

Th l ti hi f 14C t 13C fThe relationship of 14C to 13C for (A) all the samples analyzed by AMS, (B) samples shallower than 100 m (C) samplesthan 100 m, (C) samples deeper than 1000 m, and (D) all samples identified as from the northern or southernthe northern or southern hemisphere.

Polar StudiesPolar Studies

The small sample requirement made possible the detailed study of t h i i ti f h f fi d iatmospheric variation of greenhouse gases from firn and ice cores

with higher time resolution.

S ffi i l f iSufficient volumes of air can be recovered from the porous layer of ‘firn’ (compacting snow) and ice.

Bomb PulseBomb Pulse

Atmospheric Land based and Marine (mainly South Pacific) nuclear ( y )tests in the 1950-60’s created an elevated level of 14C and 36Cl in the environment.

This made possible to use 14C in younger samples and in studies ofThis made possible to use C in younger samples and in studies of oceanic and atmospheric circulations, and recharge rate and movement of underground water (aquifers, e.g. the Great Australian Artesian Basin Milk River aquifer in Canada)Artesian Basin, Milk River aquifer in Canada).

AMS in biomedical studiesAMS in biomedical studies

41C d i bi ki ti t di41Ca: used in biokinetic studies

26Al: in Alzheimer disease studiesAl: in Alzheimer disease studies

3H: tracer studies. Although the half life is short (12.33 yr), sensitivity of AMS makes it possible to use very low dosages ofsensitivity of AMS makes it possible to use very low dosages of radiation.

14C t t di A i th iti it f AMS bl f i14C: tracer studies. Again the sensitivity of AMS enables safe in-vivo studies. Pioneered at the Lawrence Livermore Laboratories.

AMS: 14C 3H as tracer in biomedical studiesAMS: 14C, 3H as tracer in biomedical studies

C, H is a major part of biological system.j g y

Sufficient amount of 14C and 3H labeled compounds to track most systems produce low level acceptable radiation dosagesystems produce low level, acceptable radiation dosage.

Biochemical Tracer work uses:

Stable isotopes (e.g. 13C, 15N)- safe but usually has insufficient sensitivity due to high natural abundancessensitivity due to high natural abundances

Short-lived isotopes (e.g. 3H): - high sensitivity but dosages required may pose radiation hazardrequired may pose radiation hazard

Long lived isotopes and low natural abundances: high sensitivity with no or very low radiation risks.

Required 14C dosage for AMSRequired 14C dosage for AMS

1 mg carbon (“modern”) contains 98 atto-mole of 14C (atto=10-18) or 7 145.9x107 14C atoms.

100 nCi of labeled compound administered to a 70 kg person will100 nCi of labeled compound administered to a 70 kg person will disperse in 42 liters of body water

100 nCi of 14C corresponds to 9 6x1014 atoms100 nCi of 14C corresponds to 9.6x1014 atoms

25 micro-liter of the water contains 5.7x108 atoms of 14C

Mixed with 1 mg modern C carrier the sample is 11x modern,Easily detected by AMSEasily detected by AMS.

15 nCi would result in about 1.2 modern- still detectable easily.

Radiation dosageRadiation dosage

14C radiation biological equivalent produces 113 attoSievert/decay.g y

A dosage of D in nCi, for biological mean life τ = 1.44xbiological half life, integrated over infinity produces a radiation dose equivalent DE:

DE (nSv)= 0.015xD(nCi)x τ (h)

1Sv=100 Rem

Conventional vs AMS dosageConventional vs. AMS dosage

Pharmaceutical industry:ytypically uses 250 μCi labeled compound for tests with biological half life of 12 h, using liquid scintillation counter, resulting in 5 mRem exposuremRem exposure.

with AMS 15 nCi is sufficient, producing 0.003 mRem radiation dosage.

Compare with:Compare with:Natural own background (14C content of body) 1.3 mRem/yNatural environment exposure (41K,U/Th,…) 250 mRem/yp ( , , ) y1 hr flight at 30,000 ft 0.02 mRem

Biomedical AMS: 14C tracerBiomedical AMS: 14C tracer

Radiation effects on a 70 kg person as a function of

10000

100000

Self Radiation for 1 yr

biological mean life of 100 nCi of 14C labeled

d1000

10000

e (n

SV

)

compound.

Nutrient100

I hr flight

tion

Dos

e

Nutrient

Toxicology10Rad

iat

1

1 10 100 1000 10000 100000Bi l i l M Lif (h )Biological Mean Life(hr)

Biomedical AMS: 14C tracerBiomedical AMS: 14C tracer

Concentrations ofConcentrations of diisopropylfluorophosphate (DFP) in mouse plasma, red blood cells and washed brainblood cells, and washed brain tissue as functions of time after a 100 ng/kg dose.

DFP binds to certain chemical in nerves and red blood cells and plasma. p

From Vogel, NIM B172(2000)884

Biomedical AMS: 14C tracerBiomedical AMS: 14C tracer

Metabolism of carotene labeledMetabolism of carotene labeled with 14C over three months.

Storage prior to final eliminationStorage prior to final elimination is demonstrated by the same area of the two last curves.

Storage

gut absorption eliminationgut absorption elimination

From Vogel, NIM B172(2000)884

Tritium AMS facilitates experiments that would otherwise be impossiblep

Determining the consequences of exposure toDetermining the consequences of exposure toenvironmentally-relevant doses of carcinogens

R t d i i t d di t W ld d t t 3H l b l d PhIP iRats administered dietarylevels of 3H-labeled PhIP, a carcinogen

found in cooked meat

We could detect 3H-labeled PhIP in liver tissue and bound to liver DNA

and protein

From M.L. Roberts, priv. comm.

Levels of 3H-labeled PhIP in rat liver tissue following dietary-relevant doses

10000

y

1000tissu

e Decay Couting Limit

100r mg

liver

t

10

3H-P

hIP

pe

1

Atto

mol

es 3

AMS Limit

0.11 10 100 1000 10000

A

Animal Dose (pmoles 3H-PhIP/kg body weight)

From M.L. Roberts, priv. comm.

Experiments to conduct double-labeling using 3H AMS and 14C AMSand C AMS

?

Study of the interaction of two independent but co-administered compounds a situation more relevant to human exposurescompounds, a situation more relevant to human exposures, has begun.

From M.L. Roberts, priv. comm.

3H and 14C dual labeling experiment3H and 14C dual labeling experiment

104

1000

104

14C-MeIQx only14C-MeIQx & 3H PhIP3H PhIP3H PhIP & 14C MeIQxue

100

3H PhIP & 14C MeIQx

/ per

g ti

ss

10

com

poun

d/

1pg c

0.10.0001 0.001 0.01 0.1 1 10

Dose (ug/kg)

K. Dingley, et al, Chemical Research in Toxicology, Vol. 11, No. 10, 1998, 1217-1222

1 MV AMS at Livermore (2002)

0.5MV AMS at U.Georgia( NEC machine)

SummarySummary

AMS h t ib t d t f i d t h l d dAMS has contributed to many areas of science and technology and made possible research which were previously difficult, tedious or simply unfeasible, e.g.

More detailed ice core studiesMore detailed ice core studiesOceanic and atmospheric circulation studiesDating of rare and precious artifacts.Quantify geomorphological processes.y g p g pIn-vivo tracer studies at safe levels

Development of new AMS applications continues vigorously for all p pp g ycosmogenic isotopes and other rare isotopes.

36Cl, 26Al, 129I are more suited to larger machines, although efforts on small (2 3 MV) machines are continuing(2-3 MV) machines are continuing.

Heavy isotopes AMS can be conducted on small machines if ultra sensitivity is not criticalsensitivity is not critical.

SummarySummary

Radiocarbon AMS is one of the most successful development in recent times, and is an enabling science and technology.

One main trend is improving the precision of dating by reducing O e a t e d s p o g t e p ec s o o dat g by educ gbackground and increasing efficiency in sample preparation.

Another important trend in AMS: biomedical and other tracer researchAnother important trend in AMS: biomedical and other tracer research using enriched 14C samples where precision is not critical. This application requires high throughput capability.

The viability of small accelerators (<1 MV) in tracer applications are clearly demonstrated. Experiments at <500 kV show promise.

Further simplification of the system will ensure wider applications and acceptance by non-physicist users. This represents a golden opportunity for such development.

Challenges and OpportunitiesChallenges and Opportunities

D l i lifi d di b AMS t ( 0 5 MV) it bl fDevelop simplified radiocarbon AMS system (<0.5 MV) suitable for tracer work, that can be used by non-specialists, requiring minimal maintenance and have high throughput capability.

The instrument must have a small footprint- i.e. table-top size. Use advanced materials e g for magnets to reduce sizeadvanced materials e.g. for magnets to reduce size.

Sample preparation and processing must be an integral part of the p p p p g g psystem.

M j k t i d h ti l i d t di lMajor market envisaged: pharmaceutical industry, medical diagnostics, nutrition, toxicology.

Think aheadThink ahead

Bio

-AM

S

AMS

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