of dating cultural heritage · dating – determination of the age of an object absolute dating of...

Introduction to the 14C method of dating cultural heritage

Ines Krajcar Bronić

Ruđer Bošković Institute, Zagreb

[email protected]

1 Zagreb, 4.6.2018.

mailto:[email protected]

mailto:[email protected]

Dating – determination of the age of an object Absolute dating of object of cultural heritage and art is one of the most important issues in art history studies and in archaeology. Accurate dating in art history is essential for valuation of original objects of arts, for differentiation between the original works and later imitations and/or frauds and for recognition of reparation and restauration works.

Radiocarbon (14C) dating is a convenient and accurate

method of absolute dating of organic materials.

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Radiocarbon (14C) dating

3

one of the most well-known radiometric methods of absolute dating

it can be applied for dating materials of biogenic origin, such as wood, charcoal, bones, grains, paper, parchment, textile, etc.

the range of 14C age determination spans from 19th century up to ~60,000 years in the past

the anthropogenic influence on the natural 14C distribution during 20th century can be used for recognition of frauds

4

Carbon isotopes

12C 13C 14C 98.89 % 1.11 % 10-10 % p = n = 6 n = 7 n = 8 stable isotopes T1/2 = 5730 y

proton

electron

neutron

14CO2

O2

AS

14 14N +n C+p

14 14C N +e + ν

Carbon on Earth

12C: 98.89 %

13C: 1.1 %

14C: 1.18 x 10-10 %

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Due to very low natural 14C concentration the radiocarbon dating method requires special techniques for chemical preparation of samples and measurement of 14C. Particular care has to be taken for sample collection and/or storage as well as during sample pretreatment and chemical preparation.

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Techniques

• Extract all carbon from a sample (fractionation)

• All carbon only from the sample (contamination)

Organic sample

Pretreatment A — B — A

Inorganic sample

Dissolution Combustion

CO2

Absorption

Catalytic reaction (Fe)

Hydrolysis

C (graphite)

C2H2

Catalytic trimerization

C6H6

Zn

Li

H2O

Carbosorb®+ Permafluor®

HCl

AMS measurement

LSC-A measurement

LSC-B measurement

Carbamate

Butyl PBD

Carbidization

Flowchart of chemical preparation techniques

for AMS, LSC-A, LSC-B methods

LSC-A

Carbonization

O2

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Accelerator Mass Spectrometry (AMS)

number of 14C atoms is counted, together with the number of 12C and 13C

Required mass: <2 mg C, <1 g sample

Measurement technique - AMS

The AMS measurement technique enables precise analysis of very small amount of samples, e.g. micro-sized samples, containing a few milligrams of carbon, or less, and is therefore applicable to various objects of cultural heritage.

Ag

Sample

CuO

Organic carbon

Graphitization line

Combustion to CO2

Collagen extraction

ABA pretreatment

AMS measurement

Preparation of targets

Reduction to C

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Fluctuations in radiocarbon activity of the atmosphere over last

1000 years

• conventional radiocarbon age of the sample, expressed in years Before Present (BP), where 0 BP = 1950 AD

• conventional 14C years do not directly equate to calendar years because atmospheric 14C concentration varies through time due to changes in the production rate

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What is the results of the measurement?

• a calibration is required to convert the conventional radiocarbon age to the calendar age

• calibration curves should be based on absolutely dated record that has carbon incorporated directly from the atmosphere at the time of formation

Radiocarbon calibration curves

ARCHIVES:

▬ Tree-rings

+ Speleothems

● Marine

sediments

■ Lake

sediments

▼ Corals

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Presentation of calibrated data

Example of a single calibrated date

Conventional radiocarbon ages (ordinate) in years BP are represented as the Gaussian

curve with mean and standard deviation (uncertainty) being 1420 ± 25 BP. Calibrated values,

in calendar years, are obtained by transferring the values on ordinate over calibration curve

to the abscissa. Results can be presented by 1σ, 2σ or 3σ probabilities and by mean or

median values.

1σ → 68.2 % probability



Standard deviations diagram

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BP

Cal AD/BC

13

Results of radiocarbon measurements expressed as

Results

Conventional radiocarbon age

Years BP, 0 BP = 1950 AD d13C normalization, Libby half-life 5568 yr

Calibrated age

Cal BC, Cal AD, probabilities and ranges Calibration by common software

Relative specific activity (more often in other applications)

pMC, permille, Fraction….

% (1)

BP

% (1)

cal BC/AD

% (1)

pMC

F14

C

How to interprete radiocarbon dates and calibrated ages?

One has to keep in mind that radiocarbon dating gives the age of material (e.g., wood) and not the time of the creation of the art work, and that the creation of the art work cannot precede the formation of the material.

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Zagreb Radiocarbon Laboratory Founded in 1968 – 50 years! Laboratory code Z

Organized 2 IAEA Training Courses on dating 2008 Regional Training Course on Dating Techniques in Archaeometry 2013 Regional Training Course on Dating of Cultural Heritage Artefacts using Nuclear Analytical Techniques Received 5 fellows for training on 14C dating

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Some interesting studies performed in the Zagreb Radiocarbon Laboratory • Egyptian Mummy from the Archaeological Museum in

Zagreb with wrappings of the Etruscan linen “book”, the Liber linteus Zagrabiensis

• Early Neolithic sites – Starčevo culture (2 sites near Slavonski Brod) • Eneolithic site – Vučedol • St. Donat church in Zadar – wooden beams • Parchment fragments from the Archives of Vojvodina, Novi Sad • Wood from the Master Buvina´s door, the Cathedral, Split • Ahdnama (The Fojnica Ahdname) • Fojnički grbovnik (The Fojnica Armorial)

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Datiranje egipatske mumije iz

Arheološkog muzeja u

Zagrebu s najvećim poznatim

etruščanskim zapisom

(Liber linteus Zagrabiensis)

Naziv uzorka Oznaka14

C starost(BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5

Tkivo mumije OxA-1386 2160 ± 80 385 - 210 cal BC

Laneni povoj Z-1653 2290 ± 40 405 - 210 cal BC

GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 901015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost(BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 901015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost(BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 901015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC






Naziv uzorka Oznaka 14

C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost(BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 901015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost (BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 90 1015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC







C starost(BP)

Kalibrirana starost

Liber linteus

Zagrabiensis

OxA-1680 2110 ± 60 360 cal BC-cal AD 5



GrN-13875 2210 ± 13 365-205 cal BC

GrN-14442 2335 ± 15 405-395 cal BC

OxA-1387 2760 ± 90

OxA-1388 2700 ± 901015-800 cal BC

Lišće Z-1654 2580 ± 60 900-520 cal BC

GrN-14467 2825 ± 15 1015-925 cal BC

OxA-1389 2920 ± 100 1400-905 cal BC

Calibrated range age

(BP) Lab. No. Sample

material

MummyTissue

Linen

wrappings

Leaves

Egyptian Mummy in Archaeological Museum in Zagreb with wrappings of the Etruscan linen “book”, the Liber linteus Zagrabiensis

Z – Ruđer Bošković Institute, Zagreb GrN – Center for Isotope Research, Groningen OxA – Radiocarbon Accelerator Unit, Research Laboratory for Archaeology and The Hystory of Art, Oxford

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Starčevo culture sites In the region of Northern Croatia about a hundred of settlements are known from the period of the Starčevo culture, the first Neolithic period in SE Europe, and 15 of them in the Sava River Basin around the city of Slavonski Brod. In this region two large and important Early Neolithic archaeological sites have been recently discovered: Zadubravlje – Dužine, and Slavonski Brod - Galovo.

Starčevo c. – Anzabegovo c. – Karanovo I c. – Cris c. – Körös c.

Radiocarbon dating of early Neolithic

Atmospheric data from Reimer et al (2004);OxCal v3.10 Bronk Ramsey (2005); cub r:5 sd:12 prob usp[chron]

Zadubravlje - Duzine

8000CalBC 7000CalBC 6000CalBC 5000CalBC 4000CalBC

Calibrated date

Z-2924 7620±140BP

Z-2923 6995±115BP

Z-3931 6919±102BP

Z-3930 6770±110BP

Z-2921 6710±115BP

Z-2922 6705±95BP

Z-3929 6673±75BP

Z-2925 6260±130BP

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• the oldest well in Croatia and the oldest known Neolithic well in Europe

• Other Neolithic wells in Europe - Linearbandkeramik Culture:

• Dendrochronological dates: 5258 cal BC (the well at Leipzig-Plaussig),

5098 cal BC and 5190 cal BC (two wells at Eythra)

5090 cal BC (Erkelenz)

• Submerged water wells in Israel - Well 66 at Atlit-Yam, 7880 ± 55 BP

(6993-6593 cal BC) considered to be the oldest well in the world.

• Well 11 at the same site is dated to 7605 ± 55 BP (6458–6385 cal BC),

i.e. it is of about the same age as the well at Zadubravlje-Dužine

Well, Pit 11 (Z-2924): 7620 ± 140 BP 6640 – 6365 cal BC (67.1%)

Zadubravlje - Dužine

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Conventional and calibrated 14C dates for samples from Slavonski Brod – Galovo.

Linear A phase of the Starčevo culture

The oldest settlement with separated burial area

Continuous existence (6070 – 4960 cal BC)

Several phases in the development proved by both archaeological findings and 14C

Atmospheric data from Reimer et al (2004);OxCal v3.10 Bronk Ramsey (2005); cub r:5 sd:12 prob usp[chron]

7000CalBC 6000CalBC 5000CalBC 4000CalBC

Calibrated date

Z-4357 7067±152BP

Z-3586 7061±152BP

Z-3584 6994±140BP

Z-3574 6875±37BP

Z-3587 6866±65BP

Z-3575 6849±58BP

Z-2936 6835±110BP

Z-3588 6822±71BP

Z-3801 6746±70BP

Z-3924 6726±147BP

Z-3803 6707±100BP

Z-3922 6709±82BP

Z-3928 6700±86BP

Z-3927 6687±45BP

Z-3926 6567±66BP

Z-3925 6398±67BP

Z-3583 6300±80BP

Z-2935 6190±130BP

Vučedol ceramic boot

Vučedol dove

Eneolithic - Vučedol (E Croatia)

Culture Approximate age span

(BC)

Baden 3500 — 2800

Kostolac 3300 — 2900

Vučedol 3000 — 2200

Old Bridge in Mostar

Stone bridge (span 28.60m) by order of the Sultan Süleyman the Magnificent in 1557 (architect Kodja Mimar Sinan) Completed AD 1566

After the reconstruction

14C dating (Obelić & al., 2007): Six wood and two charcoal samples from different periods of construction of the bridge.

Dendrochronological analyses (Kuniholm et al.

2004): 16 wood samples with visible tree rings sent to the Cornell University, Ithaca (NY, USA).

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The Ahdname – Fojnička ahdnama, expected AD 1463

24

The Fojnica Armorial, Expected – most likely 17th centur<y

manuscripts K3 and K4 with liturgical texts in Latin from the Archives of Vojvodina, Novi Sad Used as binders for the notebooks from the end of 16th cent (1569-70 AD, 1590 AD)

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Case 3. manuscripts on parchment

K3

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Lab. no Sample name Concentional 14C age (BP)

d13C (‰)

Calibrated age span (cal AD)

median cal AD

Expected period

Z-5806 A1140

Parchment K3 565 ± 20 -21.0 1325 – 1410 (68.2%)

1349 14th c.

Z-5807 A1141

Parchment K4 785 ± 20 -21.4 1225 – 1265 (68.2%)

1247 12th c.

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Wooden Beams from the Church of St. Donatus in Zadar

Obelić, Bogomil; Sliepčević, Adela. Corrections of radiocarbon age of wooden beams from St.Donat´s church in Zadar by dendrochronological method. Vjesnik Arheološkog muzeja u Zagrebu 32-33 (1999/2000) 197-206

Srdoč, Dušan; Sliepčević, Adica; Planinić, Josip; Obelić, Bogomil; Breyer, Branko. Rudjer Bošković Institute radiocarbon measurements II. Radiocarbon 15 (1973) 435-441

Srdoč, Dušan; Sliepčević, Adica; Obelić, Bogomil. Mjerenje starosti drvene građe iz crkve Sv.Donata metodom radioaktivnog ugljika. Peristil (Zbornik radova za povijest umjetnosti) 16 (1973) ; 17-20

http://bib.irb.hr/prikazi-rad?&rad=42004









































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Beam 3, oak, cut at age of 145 ± 10 years Z-178 0-10 tree rings „heart” Z-179 90-100, periphery

Original beam Reconstruction of the original cross section of the trunk

Z-178

Z-179

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Combinatin of the two results – known difference in the number of tree rings (95 - 5)

Plus: estimated number of tree rings of the whole trunk (145) – addition of 50 yr

The trunk was felled by the end of the 8th c. – beginning of the 9th c.

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Splith Cathedral – Master Buvina’s door

Height 5.24 m, width 3.51 m

During the study of the Master Buvina’s door of the Split Cathedral 14C method (AMS) was used to date 5 wood samples from the door and 2 samples

from the choir benches.

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Split-Cathedral – conventional 14

C ages

Z- Sample desc. δ13

C ‰ AMS Age σ

comm

5469 Wood, Buvina’s door, Split - Cathedral,

br.inv. M6S 6671-1 -25.0 313 80 LSC


cassette 24, (Uzašće) - wallnut, #1 -23.6 775 22


between cassetes 21-22, wallnut, #2 -24.3 879 21


middle part of the door - oak, #3 -27.1 887 21

6037 Wood (Juglans L.), Buvina’s door, Split -

Cathedral, cassette 1, #1 -23.2 784 22

6038 Wood, Split - Cathedral, Choir bench,

#2 -27.1 100.74 0.27 pMC

6605 Wood, Split - Cathedral, Choir bench,

south-west verticale 13th century, #3 -26.9 737 21

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Summary

AD 1214

Samples Z-5720 and Z-5721 from the door give the calibrated age spans cal AD 1155 – 1210 and cal AD 1054 – 1191, respectively. It may be concluded that these two wooden pieces belong to the original door from AD 1214.

Samples Z-5719 and Z-6037 are somewhat younger (cal AD 1245 – 1272 and cal AD 1225 – 1266, respectively) indicating that these pieces could not have been built into the door in AD 1214.

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Radiocarbon dating gives the age of material (e.g., wood) and not the time of the creation of the art work – however, the creation of the art work cannot precede the formation of the material

Radiocarbon dating cannot give a single year – a range of years is obtained with a certain probability, the width of the range depends on the measurement uncertainty and on the shape of the calibration curve

Interpretation of results should be performed in close collaboration of art historian and radiocarbon specialists

To remember:

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See you in the laboratory

35

Samples Z-5720 and Z-5721 from the door give the calibrated age spans cal AD 1154 – 1213 (54.9 %) and cal AD 1151 – 1209 (43.5 %), respectively. It may be concluded that these two wooden pieces belong to the original door from AD 1214.

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Samples Z-5719 and Z-6037 are somewhat younger, cal AD 1243 – 1272, 54.8 %) and cal AD 1224 – 1266 (68.2 %), respectively) indicating that these pieces could not have been built into the door in AD 1214., but they belong to 13th century.

37

Sample Z-5469 is considerably younger that the others,

it is dated to cal AD 1481 - 1650 (probability 68.2 %),

and therefore it was not a part of the original door.

38

Two samples from the choir benches

Z-6605 was dated to the second half of the 13th century (cal AD 1260 – 1285).

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Z-6038 was dated to cal AD 1955, so it may be concluded that this

piece of wood was added to the bench during reconstruction/repair

in the second half of the 20th century.

40

Summary

AD 1214

Samples Z-5720 and Z-5721 from the door give the calibrated age spans cal AD 1155 – 1210 and cal AD 1054 – 1191, respectively. It may be concluded that these two wooden pieces belong to the original door from AD 1214.

Samples Z-5719 and Z-6037 are somewhat younger (cal AD 1245 – 1272 and cal AD 1225 – 1266, respectively) indicating that these pieces could not have been built into the door in AD 1214.

Comparison of 14C AMS and LSC techniques at the Ruđer Bošković Institute

14C AMS 14C LSC

mass of C in sample / g 3.5·10-3 4-5 (2.5)

form of prepared sample graphite (+Fe) benzene

Mass of prepared sample / g 1.5·10-3 4

Measurement accuracy / pMC 0.3 0.5

Detection limit / year BP 56 200 55 000

Time of measurement <30 minutes 24 hours

No. of prepared samples per week 16 5 44

45

Radiocarbon dating – Summary

1. Constant production of 14C during last 60 000 years (calibration!)

Ra

dio

ca

rbo

n A

ge

(ye

ars

BP

) 2000

1500

1000

500

0400 AD 800 AD 1200 AD 1600 AD 2000 AD

Calibrated Age (calendar years)

Christ

3. Origin of carbon in a sample known („closed system”) (initial activity, contamination...)

2. Uniform distribution of 14C in the biosphere (stationary, well-mixed reservoirs) – d13C normalization

of dating cultural heritage · dating – determination of the age of an object absolute dating of...

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