INTRODUCTION
Twenty-two years ago, five public organizations (Table 1) joined forces to create a new accelerator mass spectrometry (AMS) facility to meet the growing demand for 14C dating in French research laboratories. In 2003, the Laboratoire de Mesure du Carbone 14 (LMC14) was set up in Saclay around ARTEMIS (French acronym for Accélérateur pour la Recherche en sciences de la Terre, Environnement, Muséologie Installé à Saclay), an AMS system based on a 3MV Pelletron purchased from National Electrostatics Corporation (NEC, Middleton, Wisconsin, USA). This new equipment replaced a multi-isotope AMS system that had been operating in Gif-sur-Yvette since the early 1980s (Arnold et al. Reference Arnold, Bard, Maurice and Duplessy1987) and the LMC14 benefited from the great experience of the Centre des Faibles Radioactivités when setting up the new preparation laboratories. The official inauguration of the National laboratory took place on 8th of April 2004. The year 2003 was dedicated to the commissioning of the AMS and the preparation laboratories. After a testing period, the first experiment was registered in 2004 and routine operation began immediately. The first 99 measurements were dedicated to oxalic acid (OX1), blanks (IAEA-C1, coral, wood), and references for carbonates (FIRI C, IAEA-C2). The first unknown sample was composed of a group of foraminifera from the Atlantic Ocean (SacA101). In a second step, references of organic matters (FIRI-A, -B, -D, -E, -G, -H) were tested and the first unknown organic sample was a modern cereal (SacA309). Accuracy, reproducibility, and blanks obtained in these early years were reported by Cottereau et al. in 2007 and then by Moreau et al. in 2013 and 2020 (Table S1).
Table 1 LMC14 supervisory bodies and proportion of 14C measurements dedicated to each of them.
From 2004 to 2014, the missions of the LMC14 were restricted to service activities due to the administrative status of the laboratory. In order to fully develop research projects, the LMC14 joined the LSCE research laboratory in Saclay (Laboratoire des Sciences du Climat et de l’Environnement). Since 2021, LMC14 has been a member of the IAEA Collaborating Center “Atoms for Heritage” of the University of Paris-Saclay.
Between 2004 and April 2023, the 14C content in 70,000 samples was measured (Figure 1). Preparation and measurement capacities have increased over the years, with up to 4874 samples produced in 2010, and between 3090 and 4200 samples per year from 2011 to 2019. 2020 and 2021 were impacted by lockdowns and lack of samples due to the Covid-19 pandemic. The year 2022 returned to an optimal activity with 3500 samples analyzed.
Figure 1 Number of samples 14C measured per year at LMC14 (Saclay, France, AMS reference laboratory SacA): in blue, for service to the five supervisory bodies and, in orange, tests, accompanying samples (primary standards, blank samples, known-age samples) and R&D samples (experimental development and research projects). Lines represent mean values from 2008 to 2022. *The year 2011 is estimated.
In this paper, 20 years of radiocarbon dating services for research institutions, museums and environmental monitoring are briefly described and results from recent archaeological and environmental research programs are reviewed. Long-term collaborative projects on rock art studies, the chronology of Pharaonic Egypt, architectural use of iron, and lead white production are presented.
MATERIALS AND METHODS
Main Equipment and Procedures
In the last 20 years, the facilities of the LMC14 have evolved and diversified to provide a large range of services. Today, the preparation laboratories are equipped with the following devices:
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Two semi-automated in-house systems for collecting CO2 from 7 organic matter samples (after combustion) and/or 5 carbonate samples (after acid hydrolysis) per day (Dumoulin et al. Reference Dumoulin, Comby-Zerbino, Delqué-Količ, Moreau, Caffy, Hain, Perron, Thellier, Setti, Berthier and Beck2017a);
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Three manual glass vacuum systems occasionally used for collecting CO2 from 7 specific samples (lead white, etc.), to seal 5 quartz tubes or to extract DIC from water samples under helium flux, respectively;
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An Elemental Analyzer coupled to an automated in-house manifold for collecting CO2 from modern samples (F14C>1). The CO2 collection line can be turned into a sealed tube graphitization line;
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A laser ablation facility (laser 1064 nm and air-tight cell) for producing and collecting CO2 from iron samples (in progress);
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Two in-house automatic systems to graphitize 24 CO2 samples daily (12 reactors of 18 and 12 mL); and
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A specific system dedicated to small samples (between 10 and 150 µg), consisting of 3 reduction lines with a small inner volume of 6 mL (Delqué-Količ et al. Reference Delqué-Količ, Caffy, Comby-Zerbino, Dumoulin, Hain, Massault, Moreau, Quiles, Setti, Souprayen, Tannau, Thellier and Vincent2013a, Reference Delqué-Količ, Comby-Zerbino, Ferkane, Moreau, Dumoulin, Caffy, Souprayen, Quilès, Bavay, Hain and Setti2013b).
14C/12C and 13C/12C ratios are determined by AMS using a 3MV NEC Pelletron equipped with two SNICS solid sources of 134 and 40 targets (Cottereau et al. Reference Cottereau, Arnold, Moreau, Baqué, Bavay, Caffy, Comby, Dumoulin, Hain and Perron2007). One of the two sources is being modified to process gas samples. The 12C3+ and 13C3+ isotopes are measured in two offset Faraday cups at the exit of the 110° magnetic analyzer. The 14C3+ are counted in an ionization chamber detector situated at the end of the beamline. The accelerator runs unattended after tuning and each sample is measured 8 to 12 times. The NEC’s abc analysis code is used to analyze offline the data produced by the AMS system. This software calculates the average 14C/12C ratio, the average 13C/12C ratio, the δ13C value for each sample and normalizes, after the removal of the anomalous measurements, the 14C/12C ratios of the unknown samples to the simultaneously measured standard sample ratio. These data are then transferred to an in-house database to determine the 14C age and the associated error. Since 2012, the samples have been registered and tracked along with the process (pretreatment, CO2 collection, graphitization, carbon isotope measurement, age in BP and δ13C value) in an Access database developed in-house. Quality control procedures are described in Moreau et al. (Reference Moreau, Messager, Berthier, Hain, Thellier, Dumoulin, Caffy, Sieudat, Delqué-Količ and Mussard2020).
Two associated laboratories—the Centre de recherche et restauration des musées de France (C2RMF) in Paris and the Centre de datation par le radiocarbon (CDRC) in Lyon—are associated to the LMC14 for the preparation of museum and archaeological samples (Billard Reference Billard2008; Richardin et al. Reference Richardin, Gandolfo, Moignard, Lavier, Moreau and Cottereau2010). Two other laboratories—the National Museum of Natural History (MNHN) in Paris and Géosciences in Paris-Saclay (GEOPS)—occasionally provide CO2 gases.
Samples
Since 2004, 69 850 samples have been handled in total (Figure 1). ∼45,000 unknown samples have been analyzed for service purposes and research projects and ∼25,000 samples have been measured as accompanying samples (primary standards, blank samples, known-age samples) or for tests.
For service purposes, the three laboratories (LMC14, C2RMF, CDRC) together prepare all the conventional materials (wood, charcoal, sediments, bones, ivory, hair, textile, cellulose, etc.) (Table 2). For research projects or for specific applications, the LMC14 has continuously improved its capabilities by implementing new devices and developing new protocols. Dedicated preparation protocols have been developed for water (Dumoulin et al. Reference Dumoulin, Caffy, Comby-Zerbino, Delqué-Količ, Hain, Massault, Moreau, Quiles, Setti, Souprayen, Tannau, Thellier and Vincent2013), bone (Dumoulin et al. Reference Dumoulin, Messager, Valladas, Beck, Caffy, Delqué-Količ, Moreau and Lebon2017b), iron (Leroy et al. Reference Leroy, L’Héritier, Delqué-Kolic, Dumoulin, Moreau and Dillmann2015a), lead carbonates (Beck et al. Reference Beck, Messager, Coelho, Caffy, Delqué-Količ, Perron, Mussard, Dumoulin, Moreau and Gonzalez2019; Messager et al. Reference Messager, Beck, de Viguerie and Jaber2020), oxalates (Dumoulin et al. Reference Dumoulin, Lebon, Caffy and Mauran2020), and more recently mortars (Hayen et al. Reference Hayen, Van Strydonck, Fontaine, Boudin, Lindroos, Heinemeier, Ringbom, Michalska, Hajdas and Hueglin2017; Moreau et al., Reference Moreau, Dumoulin, Jaber, Caffy, Delqué-Kolic, Goulas, Hain, Perron, Setti and Sieudatsubmitted). The LMC14 has also participated in several international inter-comparisons (Cuzange et al. Reference Cuzange, Delqué-Količ, Goslar, Grootes, Higham, Kaltnecker, Nadeau, Oberlin, Paterne and van der Plicht2007; Quiles et al. Reference Quiles, Valladas, Geneste, Clottes, Baffler, Berthier, Brock, Ramsey, Delqué-Količ and Dumoulin2014; Scott et al. Reference Scott, Naysmith and Cook2017; Moreau et al. Reference Moreau, Messager, Berthier, Hain, Thellier, Dumoulin, Caffy, Sieudat, Delqué-Količ and Mussard2020) and more recently in the GIRI and MODIS2 campaigns (Scott et al. Reference Scott, Naysmith and Cook2019; Dumoulin et al. Reference Dumoulin, Caffy, Delqué-Količ, Farcage, Goulas, Hain, Moreau, Perron, Semerok, Sieudat, Thellier and Beckaccepted; Moreau et al. Reference Moreau, Dumoulin, Jaber, Caffy, Delqué-Kolic, Goulas, Hain, Perron, Setti and Sieudatsubmitted).
Table 2 Materials prepared for service (X) at the LMC14 and the associated preparation laboratories (C2RMF and CDRC) and for collaborative research projects only (*).
Figure 2 presents the diversity of substances measured at the LMC14. Unsurprisingly, charcoals, wood and plants are the most frequently dated samples (35%), followed by calcium carbonate-based materials such as foraminifera, speleothems, shells (18%) (Figure 2a). Sediment, peat, and soils account for 13% but this proportion is increasing continuously as for water (5%), which has been prepared only since 2012. Bones prepared in the associated laboratories represent 10% of the measurements. Many minor types of samples are also handled in response to users’ requests or for research purposes (Figure 2b).
Figure 2 Types of samples 14C analyzed at the LMC14. (a) Major materials (>5%) represent 82% of the dated samples. (b) Many varieties of minor materials are also handled (<5%). All the types of materials are prepared at the LMC14 except bones and ivory prepared at C2RMF and CDRC.
ACHIEVEMENTS
Service Activity
Almost 40,000 samples have been measured for the service to the French research laboratories of the supervisory bodies (CNRS, CEA, IRD, IRSN, and MC), corresponding to 2000–3000 samples per year over the 12 years before Covid-19 (Figure 1).
Each institution organizes the access to 14C measurements according to their own selection procedure. After acceptance of the proposal, the cost per sample for the user varies according to the institution, from free of charge to a reduced fee. About 50% of 14C measurements are dedicated to environmental studies (past climate, carbon cycle, ocean studies, evolution of eco-hydrosystems and soils, sustainable development, etc.), 40% for cultural heritage applications (archaeological sites, museums, preventive and academic archaeological excavations) and 10% for radiological monitoring. Two-thirds of the dated samples are prepared on site using the facilities described above and one-third is prepared in the two associated laboratories, C2RMF and CDRC.
Results delivered to the users are the 14C content in pMC and 14C age in BP with their respective uncertainties and δ13C values for information. For environmental monitoring, the results are expressed in Bq per kg of carbon. The users publish the results on their own. The publication must include the “SacA” AMS laboratory code and a mention of the “ARTEMIS programme” in the Acknowledgments section. However, when specific development is required, a collaborative project between LMC14 and the users can be set up, leading to a joint publication of the results.
Research Projects
Research projects are conducted internally or in collaboration with external partners. They are mainly in the field of archaeology and art history and cover the period from the Palaeolithic to contemporary times. Long-term research programmes have been dedicated to the chronology of Pharaonic Egypt (Bronk Ramsey et al. Reference Bronk Ramsey, Dee, Rowland, Higham, Harris, Brock, Quiles, Wild, Marcus and Shortland2010; Quiles et al. Reference Quiles, Aubourg, Berthier, Delque-Količ, Pierrat-Bonnefois, Dee, Andreu-Lanoë, Bronk Ramsey and Moreau2013, Reference Quiles, Emerit, Asensi-Amorós, Beck, Caffy, Delque-Količ and Guichard2021a, Reference Valladas, Kaltnecker, Quiles, Tisnérat-Laborde, Genty, Arnold, Delqué-Količ, Moreau, Baffier and Merle2021b) and rock art studies.
Concerning the latter topic, the LMC14 has long experience in dating rock art. Drawings and paintings of many decorated Paleolithic caves located in France (Chauvet, Cosquer, Grottes aux points, les deux ouvertures, Villars), in Spain (Nerja) and more recently of rock shelters in Italy and in Africa have been investigated (Genty et al. Reference Genty, Konik, Valladas, Blamart, Hellstrom, Touma, Moreau, Dumoulin, Nouet, Dauphin and Weil2011; Beck et al. Reference Beck, Genty, Lahlil, Lebon, Tereygeol, Vignaud, Reiche, Lambert, Valladas and Kaltnecker2013; Valladas et al. Reference Valladas, Kaltnecker, Quiles, Tisnérat-Laborde, Genty, Arnold, Delqué-Količ, Moreau, Baffier and Merle2013, Reference Valladas, Quiles, Delque-Kolic, Kaltnecker, Moreau and Pons-Branchu2017; Quiles et al. Reference Quiles, Valladas and Bocherens2016; Dumoulin et al. Reference Dumoulin, Lebon, Caffy and Mauran2020; Palmerini et al. Reference Palmerini, Beck and Di Martino2021; Heimlich et al. Reference Heimlich, Pons-Branchu, Valladas, Dapoigny and Dumoulin2022; Pons-Branchu et al. Reference Pons-Branchu, Barbarand, Caffy, Dapoigny and Drugat2022). For the Chauvet cave (France), more than 250 AMS-radiocarbon dates have been performed by different laboratories since its discovery in 1995 (Quiles et al. Reference Quiles, Valladas and Bocherens2016). Among them, 111 were obtained using the ARTEMIS AMS facility after sample preparation at the LMC14 or in sister laboratories (LSCE [Gif-sur-Yvette], MNHN [Paris], CDRC [Lyon]). 14C measurements were carried out on 19 drawings and 11 charcoal marks and on 17 humic fractions. To document human occupation, more than 160 charcoals from the cave floor were analyzed for dating and intercomparison (Cuzange et al. Reference Cuzange, Delqué-Količ, Goslar, Grootes, Higham, Kaltnecker, Nadeau, Oberlin, Paterne and van der Plicht2007; Quiles et al. Reference Quiles, Valladas, Geneste, Clottes, Baffler, Berthier, Brock, Ramsey, Delqué-Količ and Dumoulin2014), of which 64 were measured using the ARTEMIS facility. Based on the radiocarbon dates, a high-precision chronological model was developed showing that there were two distinct periods of human activity in the cave, one from 37 to 33,500 yr ago, and the other from 31 to 28,000 yr ago (Quiles et al. Reference Quiles, Valladas and Bocherens2016).
For the Cosquer cave, 41 samples have been dated since its discovery including 25 14C analyses by ARTEMIS. Charcoal samples taken from animal representations, hand stencils and signs were dated. The results showed that the Cosquer Cave was visited by prehistoric people over a long period, between 33,000 and 20,000 cal BP and that the oldest decoration period falls in the same time range as the Chauvet Cave’s latest occupation (Valladas et al. Reference Valladas, Quiles, Delque-Kolic, Kaltnecker, Moreau and Pons-Branchu2017). In the Villars cave, five radiocarbon dates were obtained from torch marks, sampled after analyzing 22 representations in situ by X-ray fluorescence (Beck et al. Reference Beck, Genty, Lahlil, Lebon, Tereygeol, Vignaud, Reiche, Lambert, Valladas and Kaltnecker2013). The dates range from 22.1 to 17.1 cal ka BP. These three sites present varied examples of decorated caves, showing the longevity over at least 20 centuries and the spatial distribution of rock art in France.
Since the last decade, one of the objectives of the LMC14 has also been to explore the possibility of extending the range of datable materials by handling non-conventional materials such as iron and lead carbonates. These approaches are detailed in the following sections.
Iron
Dating archaeological ferrous objects is essential to investigate the history of iron and steel. Until modern times, ore was reduced to metal in furnaces using charcoal. During the reduction process, part of the charcoal carbon diffused into the metal and was incorporated into the structure of the ferrous alloy in the form of iron carbide Fe3C (cementite). By extracting carbon from the metal matrix, it is possible to date the tree from which the charcoal was obtained and thus estimate the age of the metal itself. However, due to the complex and heterogeneous structure of ferrous alloys, it is necessary to fully characterize the samples prior to 14C dating. For that purpose a close collaboration was established 10 years ago between the LMC14 and the Laboratoire Archéomatériaux et Prévision de l’Altération (LAPA-IRAMAT, NIMBE, CEA, CNRS, Université Paris-Saclay). A rigorous analytical framework was defined not only to avoid sources of contamination due to the presence of corrosion zones and recycled steel, but also to determine the most carburized sectors and thus the most relevant ones for the analysis by carbon 14 (Leroy et al. Reference Leroy, L’Héritier, Delqué-Kolic, Dumoulin, Moreau and Dillmann2015a).
The use of this protocol in the study of monuments and archaeological sites is already contributing to extending our knowledge on the use of iron in the construction of Gothic cathedrals (Leroy et al. Reference Leroy, Hendrickson, Delqué-Kolic, Vega and Dillmann2015b; L’Héritier et al. Reference L’Héritier, Azéma, Syvilay, Delqué-Kolic, Beck and Guillot2023), the diffusion of ferrous alloys in the Iron Age and Antiquity (Delqué-Kolic et al. Reference Quiles, Valladas, Geneste, Clottes, Baffler, Berthier, Brock, Ramsey, Delqué-Količ and Dumoulin2017; Berranger et al. Reference Berranger, Dillmann, Fluzin, Vega, Aubert, Leroy and Delqué-Količ2021; Berthaut-Clarac et al. Reference Berthaut-Clarac, Nantet, Leroy, Delqué-Količ, Perron, Adam, Schaeffer and Kerfant2022) and the role of iron in the development of the Khmer Empire (Leroy et al. Reference Leroy, Hendrickson, Delqué-Kolic, Vega and Dillmann2015b, Reference Scott, Naysmith and Cook2018, Reference Scott, Naysmith and Cook2020). A novel approach is being developed for in situ sampling of iron armatures of bronze Khmer statues (Leroy et al. Reference Leroy, Delqué-Količ, Vincent, Baptiste, Vega, McGill and Fenn2021). The protocol is described in Dumoulin et al. (Reference Dumoulin, Caffy, Delqué-Količ, Farcage, Goulas, Hain, Moreau, Perron, Semerok, Sieudat, Thellier and Beckaccepted).
Lead Carbonate and Lead White
Lead carbonates were employed as cosmetics, eye remedies and white pigment (known as lead white) from the 4th century BC to the beginning of the 20th century. Recently, it has been demonstrated that organic carbon was incorporated during their manufacturing, making 14C dating possible (Beck et al. Reference Beck, Caffy and Delqué-Količ2018; Hendriks et al. Reference Richardin, Gandolfo, Moignard, Lavier, Moreau and Cottereau2019; Messager et al. Reference Messager2022). Protocols based on the thermal decomposition of lead carbonates have been developed at LMC14 in order to avoid contamination by dead carbon from calcite or other carbonate compounds potentially mixed with them (Beck et al. Reference Beck, Messager, Coelho, Caffy, Delqué-Količ, Perron, Mussard, Dumoulin, Moreau and Gonzalez2019; Messager et al. Reference Messager, Beck, de Viguerie and Jaber2020; Dumoulin et al. Reference Dumoulin, Caffy, Delqué-Količ, Farcage, Goulas, Hain, Moreau, Perron, Semerok, Sieudat, Thellier and Beckaccepted).
14C analysis of Egyptian and Greek cosmetics showed that phosgenite (Pb2(CO3)Cl2) was synthesised as early as the middle of the 2nd millennium BC and cerussite (PbCO3) from the 4th century BC (Beck et al. Reference Beck, Caffy and Delqué-Količ2018). 14C dates were also obtained from lead carbonate compounds used as eye collyria during the Roman period in the 2nd century AD (Messager et al. Reference Messager2021). Medieval mural paintings were also investigated. Dating results attested the use of lead white for the decoration of private homes such as the castle of Germolles (France) at the end of the 13th century or larger public buildings such as churches, in Angers at the beginning of the 12th century (Duchene in prep.) or later in Fribourg in the 15th century (Beck et al. Reference Beck, Messager, Caffy, Delqué-Količ, Perron, Dumoulin, Moreau, Degrigny and Serneels2020). Including papers published by ETH, Zurich, Switzerland (Hendrick et al. Reference Sá, Hendriks and Cardoso2020; Sa et al. Reference Valladas, Quiles, Delque-Kolic, Kaltnecker, Moreau and Pons-Branchu2021), these studies provide direct evidence of the capacity of the radiocarbon method to directly date lead carbonates and extend the range of inorganic materials that are datable by this method.
More recent collaborative research projects have focused on societal issues such as the protection of cultural heritage (Hajdas et al. Reference Hajdas, Jull, Huysecom, Mayor, Renold and Synal2019). An illicit production of fake paintings was uncovered by radiocarbon dating in the context of a police investigation conducted by the French Central Office for the Fight against Illicit Trafficking in Cultural Property (OCBC) (Beck Reference Beck2022; Beck et al. Reference Beck, Caffy, Mussard, Delqué-Količ, Moreau, Sieudat, Dumoulin, Perron, Theillier and Hain2022b). Concerning museum objects, a controversy of more than a century about the attribution of the Flora bust to Leonardo da Vinci has also been definitively resolved after dating the object to the 19th century (Reiche et al. Reference Reiche, Beck and Caffy2021; Beck et al. Reference Beck, Caffy, Delqué-Količ, Dumoulin, Hain, Moreau, Perron, Sieudat, Thellier and Van Hove2022a). Finally, the disaster of the fire of Notre-Dame de Paris on April 15, 2019, led to the creation of a vast scientific project in parallel with the restoration work. The unfortunate destruction miraculously spared part of the frame and made the wooden pieces and metallic structure accessible to the scientific community. In the context of a programmatic action, the LMC14 is involved in two projects. The first one investigates the role of iron in the construction of this monument (L’Héritier et al. Reference L’Héritier, Azéma, Syvilay, Delqué-Kolic, Beck and Guillot2023), following the studies carried out on numerous Gothic churches (see above). The second aims at implementing the 14C recorded in the wooden beams at a yearly resolution in the next 14C calibration curve and documenting past changes in 14C production resulting either from changes in solar activity or supernovae (Daux et al. 2022).
In addition to cultural heritage applications, the LMC14 has been involved in various programs on environmental studies (Haddam et al. Reference Haddam, Siani and Michel2018; Pons-Branchu et al. Reference Pons-Branchu, Bergonzini, Tisnérat-Laborde, Branchu, Dumont, Massault, Bultez, Malnar, Kaltnecker and Dumoulin2018; Rapuc et al. Reference Rapuc, Sabatier and Arnaud2019; Waelbroeck et al. Reference Waelbroeck, Lougheed and Vazquez Riveiros2019). In other cases, 14C was used as a tracer to better understand the carbon cycle in water ecosystems such as lakes (Messager Reference Messager2020; Thouret et al. Reference Thouret, Boivin, Miallier, Donnadieu, Dumoulin and Labazuy2021), rivers (Dumoulin et al. Reference Dumoulin, Pozzato, Rassman, Toussaint, Fontugne, Tisnérat-Laborde, Beck, Caffy, Delqué-Količ, Moreau and Rabouille2018; Pozzato et al. Reference Pozzato, Rassmann and Lansard2018), or oceans (Dumoulin et al. Reference Dumoulin, Rabouille, Pourtout, Bombled, Lansard, Caffy, Hain, Perron, Sieudat and Thellier2022). The isotopic analyses (δ13C, Δ14C) of the pore waters trapped in this sediment and of the sediment itself give valuable information to follow the fate of the organic matters of terrestrial or marine origin.
CONCLUSION
The Laboratoire de Mesure du Carbone 14 has just celebrated its 22 years of existence and its 20 years of carbon 14 measurements for the French scientific community. After two years impacted by the Covid pandemic, the LMC14 has recovered its full production capacity with more than 3500 samples per year. The data produced contribute to research efforts in the fields of environmental studies—paleoclimatology, carbon cycle, ocean studies, evolution of eco-hydrosystems and soils, sustainable development—cultural heritage—for museums and archaeological services—as well as for environmental monitoring. Since 2015, the laboratory has been attached to the Laboratoire des Sciences du Climat et de l’Environnement, which enables it to carry out research projects in parallel with the service activities. Long-term research programs have been developed, among others, on the chronology of Pharaonic Egypt, prehistoric rock art, the use of iron in the medieval buildings, the manufacture of the lead white pigment, the protection of cultural heritage and the carbon cycle in water ecosystems. Since 2021, the LMC14 has been a member of the IAEA Collaborating Center “Atoms for Heritage” of the University of Paris-Saclay.
ACKNOWLEDGMENTS
The authors wish to associate to this paper the former directors, staff members and PhD students of the LMC14 for their invaluable contribution: Evelyne Cottereau, Bernard Berthier, Maurice Arnold, David Bacquet, Dominique Bavay, Clothilde Comby, Nicolas Durand, Samira Ferkane, Stéphanie Leroy, Cyrielle Messager, Baptiste Mollet, Sophie Morelli, Solène Mussard, Anita Quiles, Christelle Souprayen, Charlotte Van Hove, Julien Vincent, and many undergraduate students and interns. This article is dedicated to the memory of Joseph Salomon.
Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.1017/RDC.2023.23
