Nagoya University
NagoyaUniversity

The ErlangenAMS-facility:status,measurements

applications

the prospectof i4C

andsamplesof microgram

Woligang Kretschmer
PIrysikalisches
institu4Uhiversitd't
Eriangen,Germany

The ErlangenAMSMVEN tandem

facility
consists

accelerator,

anof

analyzingin a hybridsputter ion source fromNEC, pre-to 50 keV and iajected
intothe accelerator

accelerated

deflector
andi2C

900 magnet

aions.
At 5 MVby a combinationofa

fbr the sequential

i4c, i3c
iniectionoffastisotopeswitchingwithterminal voltage

6aand a heavy ion detector.
Negativespectrometer

ionsare generated from solid or gas samples

andionsource, an iajection
spectrometer,a negative

the most

900 electrostatic

positivecharge state is4+, which
150 electrostatic deflector
and a 550 magnet.

abundant

isanalyzed ina mass spectrometer consisting ofa
Finallythe stable ionsi3C and i2C are measured inFaradaycups

i4C

andisdetectedina AE-E

fbrthe remaining
background.The beam transport
gas detector,which serves as a lastfilter
betweeniajectionand analyzing magnet is completely performed by electrostatic
devices,

identical
ionoptics fbrthe diffbrentcarbonensureswhichfrom unprocessed

obtained

is O.02 percent modern
graphite samples
to an apparent age of about 69.400years.

corresponding

The conversionof raw

negative

ionsusually involvesthree steps. First,
the samples

carbonto removehumic

carbonacids

to sputter

samplescompounds

which

in soil or conservationa typical carbon

content of aboutananalyzer

elemental

measurement

arerepresentative

1 mg isoxidized

to C02, which(EA),fbllowed by a stable massof 6i3Cfrom 19t6of the C02. Third,C02

connected

in a closed

vacuumlinewith minimurne.g.

iscatalyticallyreduced

thatboth combustion

the background from procession andisabout O.08pMC

the range

samplessoil, pollen,bones,mussels) attempts(charcoal,datingofironof

57.300 years. To extend

age

artefacts andIimemortar, which

of

and

material

withapplications

have been madeto carbon
andfrom outsidecontamination

apparentcarbonates

isperfbrmedat Erlangenin
spectrometerfbr precisionand time saving way.

machinepre-treatedare chemicallyboth processescan be perfbrmedin a fu11yautomatedsamplefbrmationof

efficient

forthe age,(pMC)

carbonin artefacts. Second,the remaining

material

high temperature.The use of an EA hasthe bigadvantage
arefbr antargets suitable

notbackgroundisotopes.
The machine

atreduction
andthat

For a typical1 mg
corresponding

beyond ourto anstandard

fbrthe radiocarbon

involvesdifferent
techniques.
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Nagoya University
NagoyaUniversity

Radiocarbon dating of ancientiron artefacts is possible
due to their slightcarboncontent1(O,3.5%) that originates from the ironsmelting process,which has been poweredby charcoal
until about the 18thcentury.
Two alternative methods have been tested,directsputtering fromand the extraction of carbon

the pre-cleaned
samplebut directsputtering is on}y reasonable

results,using

piecesof wood

wood

at

the time

incorporationis unclear,ofto theirdifferent
microscopic

stmctureused

to produce C02 fbr AMS

andwilldatingofa

calcium

applications

in environniental

especialiy

AMSofold calcium

to be possible
due

seems

thestudies

amountisextremely low even ifa largeamountmeasuremenis

Therefbrean

extension

ishighlydesirable,butthisinvolves
newsolidwith

phosphoricacid
promising
will be shown,
aremummy".

soil, air) is collected.

micrograrn

aof limemortar

Firstresults fbrboth methods

measurements.

"Persian

applications

radiocarbon

i4C-backgroundofcarbon

of natural sample

the carbon

and elaborate

ofmass

range

fbr

(rain

down totechniques,
since with theinverselyproportional
to the carbon
mass
lessthan 1OO pg the EA isdirectly
coupled to the gas ion source via
thus avoiding
the usual reduction
to carbon andgas handlingsystem,

targetsthe

For a carbon

mass.

content, sincetested using

wasand theirdifferent
reaction times withbe discussed.Some interestingarchaeologicali4C

somenormal

methodfrom other sources. Separationof the different
carbonates

carbonatewater,

anotheristhe possiblecontamination

Problem with this methodForhigh carbon

withprodnced from slaked lime and the C02 from the air duringthe setting of mortar.

carbonatee.g, theforsamples

givereliable

qurrentistoo small, Radiocarbondatingof lime mortar isoften done byor charcoal
incorporated
inthe mortar. But, since origin and age of thethe source

otherwise

HCI. Both approaches

via

fu11yautomatedrises

roughlypressing the iron-carbonmixturecarbon

withapplication

intetarget holders,With this method calibration samples
withreasonableresults. As an
lessthan 5 pg have been measured

mass
theorigininvestigated
via theirof trichloroacetic

i4Ccontent.

(TCA) in Bavarian fbrest soil has been

acid

foran irijection
pre-treatedresultingin a well separated(GC),

The soil has been chemicallyintoa two-dimensional preparativegas chromatograph
TCA peak containing a carbon mass of 1.5 pg, the blank sample
procedureand GC separation,
fbr the soil sample
areofcurrently working

carbonbut withoutsoil,

had a carbon

2,2 ± O.2 pMC indicatesanthropogenicQn

a directcouplingof GC, EA

andwiththe samechemicali4C

origincontentpg. The
of TCA in forest
soil. We

AMS

facility
to minimize

massof0.21

anycontamination.

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