IsoTrace Laboratory Research Articles

The André E. Lalonde AMS Laboratory – The new accelerator mass spectrometry facility at the University of Ottawa

The University of Ottawa, Canada, has installed a multi-element, 3MV tandem AMS system as the cornerstone of their new Advanced Research Complex and the principal analytical instrument of the André E. Lalonde Accelerator Mass Spectrometry Laboratory. Manufactured by High Voltage Engineering Europa B.V., the Netherlands, it is equipped with a 200 sample ion source, a high resolution, 120° injection magnet, a 90° high energy analysis magnet (mass-energy product 350MeV-AMU), a 65°, 1.7m radius electric analyzer and a 2 channel gas ionization detector. It is designed to analyze isotopes ranging from tritium to the actinides and to accommodate the use of fluoride target materials. This system is being extended with a second injection line, consisting of selected components from the IsoTrace Laboratory, University of Toronto. This line will contain a pre-commercial version of the Isobar Separator for Anions, manufactured by Isobarex Corp., Bolton, Ontario, Canada. This instrument uses selective ion–gas reactions in a radio-frequency quadrupole cell to attenuate both atomic and molecular isobars.This paper discusses the specifications of the new AMS equipment, reports on the acceptance test results for 10Be, 14C, 26Al and 127I and presents typical spectra for 10Be and actinide analyses.

Bronze Age metal artefacts found on Cyprus - metal from Anatolia and the Western Mediterranean

Hundreds of Bronze Age metal artefacts excavated on archaeological sites in Cyprus have been analysed for their lead isotope and elemental composition in the Isotrace Laboratory, University of Oxford, in the years 1982-2002. In parallel, but in particular after 1995, hundreds of samples of minerals and slags collected from the mines and smelting sites around the Troodos Mountains were also analysed. Most of the results were published in various articles over the years, but the interpretation of some of the lead isotope data needs a current revision in view of new research conducted in Spain, Sardinia and southern France. It has been known that the lead isotope data for metal artefacts from the Cypriot Bronze Age sites shows that not all of the copper is consistent with origin from the Cypriot ores. In addition, the lead and silver artefacts found there must have been imported, because there are no lead or silver ores on Cyprus. The re-evaluation of the data shows that about 11 % of the analysed metal artefacts are consistent with the origin from the deposits in the Aegean and Turkey, while about 14 % with sources in the Western Mediterranean. This paper discusses in detail the current interpretation of the research into the sources of imported metal found in the Bronze Age context on Cyprus.

Metal provenancing using isotopes and the Oxford archaeological lead isotope database (OXALID)

This paper reviews the research into the methodology of lead isotope provenance studies carried out at the University of Oxford between 1975 and 2002, at first in the Department of Geology (Geological Age and Isotope Research Laboratory), later in the Isotrace Laboratory based in the Department of Nuclear Physics, and eventually part of the Research Laboratory of Archaeology and the History of Art. These 27 years of intensive work, funded initially by the Stiftung Volkswagenwerk, and later from numerous UK Government and Charitable funds and finally by the Institute of Aegean Prehistory laid the foundations of the lead isotope provenance methodology and resulted in a large database of analytical isotope and elemental results. In spite of the efforts of the authors, this database is still not comprehensively published or easily accessible in a digital format by all researchers interested in using this method for their projects. The possibilities of advancing this situation are discussed. The authors discuss in detail the basic restrictions and advantages of using the lead isotope compositions of ores in mineral deposits for finding the origin of the raw materials used for making ancient artefacts. Methods for the scientific interpretation of the data are discussed, including attempts to use statistical methods. The methodology of creating the Oxford lead isotope database (OXALID) is outlined and a summary is given of the lead isotope resource provided by OXALID.

COINS, ARTEFACTS AND ISOTOPES—ARCHAEOMETALLURGY ANDARCHAEOMETRY*

Archaeometallurgy is one of the earliest manifestations of archaeometric research, using science‐based approaches to address cultural–historical questions. This review first outlines the extent of the field, defining in some detail the main branches of archaeometallurgy, and their specific methodological approaches. It then looks at some of the early publications pioneering archaeometallurgical research, to set the scene for the publication pattern of archaeometallurgy in general, and the role thatArchaeometryplayed in publishing archaeometallurgical research. The analysis of archaeometallurgy‐themed publications inArchaeometry, their change over time and their relationship to the total range of work done in the field indicates that there is a rather narrowly defined and specific type of archaeometallurgy that gets published inArchaeometry, initially with a strong focus on coin and object analysis, often combined with method developments. The more recent developments in isotope‐based studies in archaeometallurgy find only a limited representation in the journal, despite the leading role that the Isotrace Laboratory played in this discipline, for some considerable length of time. More recently, thisArchaeometry‐specific ‘flavour’ of archaeometallurgy seems to weaken, with an increase of papers on iron and on primary production in general, subjects still much under‐represented.

LEAD ISOTOPE DATA FROM THE ISOTRACE LABORATORY, OXFORD: ARCHAEOMETRY DATA BASE 2, GALENA FROM BRITAIN AND IRELAND

ArchaeometryVolume 38, Issue 1 p. 165-180 LEAD ISOTOPE DATA FROM THE ISOTRACE LABORATORY, OXFORD: ARCHAEOMETRY DATA BASE 2, GALENA FROM BRITAIN AND IRELAND B. M. ROHL, B. M. ROHL Isotrace Laboratory, Department of Physics, Keble Road, Oxford, OX1 3RH. U.K.Search for more papers by this author B. M. ROHL, B. M. ROHL Isotrace Laboratory, Department of Physics, Keble Road, Oxford, OX1 3RH. U.K.Search for more papers by this author First published: February 1996 https://doi.org/10.1111/j.1475-4754.1996.tb00769.xCitations: 86AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume38, Issue1February 1996Pages 165-180 RelatedInformation

New Chronometric Dates for the Puquios of Nasca, Peru

Numeric age assessments of organic material encapsulated by rock varnish present on stone lintels of two “puquios” in the Nasca region of the south coast of Peru indicate a Precolumbian age. Accelerator mass spectrometry radiocarbon analyses at the Isotrace Laboratory revealed ages of cal A. D. 560(620)650 and cal A. D. 600(640)660 (1 sigma). These calibrated measurements are considered to be appropriate in the context of the archaeological settlement pattern data for the region. As well, the written documents of the colonial period neither confirm nor deny the presence of the puquios. Three assumptions are inherent in the acceptance of these dates: (1) AMS14C dating and its application to rock varnish yield reliable results, (2) sample contamination can be recognized, and (3) determination of the age of the puquios rests upon testable available information; ex silentio arguments about the presence or absence of the puquios in the Nasca region before the Spanish conquest are inadequate for the resolution of the question.

The AMS facility at Gif-sur-Yvette: progress, perturbations and projects

We report on developments at the Gif-sur-Yvette AMS facility since 1990. On the technical side these include: (i) installation of a new dual port injection line based on a rotating electrostatic analyzer designed and constructed by IsoTrace laboratory; (ii) new estimates of 10Be efficiency and background; (iii) the failure of one of the Delrin compression rods on the column, resulting in the rupture of the low energy accelerator tube; (iv) plans (unfortunately not yet fulfilled) to add a second high energy line to permit analysis of ions heavier than mass 30. We also give a brief resumé of the research programs currently being carried out using 10Be and 26Al.

Procedures and precision in 14C AMS

Reproducibility and accuracy are both major concerns in 14C dating so the onus of demonstrating high precision in accelerator mass spectrometry (AMS) has therefore fallen largely on the application of 14C dating. At the IsoTrace laboratory, procedures were developed for 14C AMS to produce precisions of 0.2% or ± 16 years and, most importantly, the results at these precisions were demonstrated to be reproducible and accurate.

Lanthanide negative ion detection using accelerator mass spectrometry

Accelerator mass spectrometric methods have been used in the detection of the negative ions of the lanthanides. All of the lanthanide negative ions (La −−Lu −) have been observed except Pm −, Ho −, and Er −. The heavy element analysis line at the IsoTrace Laboratory was used to count the positive ions resulting from the atomic negative ions produced in a Cs sputter ion source and passed through the tandem accelerator. Because of its very low electron affinity, Dy − had a terminal voltage dependent yield, and its study required the reduction of the electric field gradients used to accelerate the ions. The relative negative ion yields among the lanthanides will be discussed. Both Yb − and Lu − have recently been theoretically predicted to exist in negative parity ground states.

THE ORIGIN of METAL OBJECTS FROM the EARLY BRONZE AGE SITE of THERMI ON the ISLAND of LESBOS

Summary: Lead isotope analysis of metal are deposits in the Mediterranean provides an important database for provenance studies of ancient metal artefacts. the Isotrace laboratory at Oxford has accumulated during the past decade well over 2000 lead isotope data on copper and lead ores and these data (in addition to analyses published by other groups) can be used for comparisons with lead isotope compositions of ancient metal objects. In a search for the roots of Early Bronze Age metallurgy in Europe we have analysed 34 copper‐based objects from the Early Bronze Age strata of the town of Thermi on the Aegean island of Lesbos. the results of lead isotope analysis show that the metal objects on this site have a quite varied origin. Some of the objects are made of copper consistent with an origin from the mineral deposits of the Troad whilst others might be made of copper from the Cyclades. However, there are also some objects which are not made of copper from any of the Aegean deposits. These imports have later parallels on the site of Kastri on Syros and amongst the objects excavated by Schliemann at Troy.

Recent developments in AMS at the IsoTrace laboratory

The equipment required for the accelerator mass spectrometry (AMS) analysis of heavy elements using small tandem accelerators is reviewed, and examples of the analytical capability for 129I and precious metals, including the platinum group elements, are given.

Operations, analytical work and research at the IsoTrace Laboratory

A review of work during the past several years at the IsoTrace Laboratory is presented. The use of three diagnostic procedures which provide early notice of equipment failure is discussed, and recent advances in radiocarbon analysis are outlined.

Heavy element analysis by low energy accelerator mass spectrometry

Improvements have been made to the mass and energy analysis system at the IsoTrace Laboratory that have resulted in a factor of 30 increase in detection efficiency for some heavy ions and have reduced interference from the fragmentation of hydrides and other molecules. The implications of these improvements for the detection of rare atomic negative ions and radioisotopes such as 129I will be discussed. Evidence is also presented for the existence of a barium negative ion that is completely resolved from barium mono-, di- and trihydride interferences and which is clearly distinguished from any interference due to the fragmentation of BaH − 2 to BaH − before the first analyzing magnet.

Accelerator mass spectrometry at Toronto

Progress in accelerator mass spectrometry at the IsoTrace Laboratory is outlined. Results from calculations on quantum mechanical effects in the sputter source which influence isotope fractionation are presented with examples from radiocarbon analysis. Advantages accruing from the installation of an electric analyser in the low energy beam transport system are discussed with examples from chlorine and carbon analysis.