This is the written version of a retrospective talk given at the 20th Radiocarbon Conference in Hawaii, 2009. As requested, this is not a scholarly work, but simply a personal, subjective account of how a good experiment in the field of radiocarbon dating came about. It differs from the talk itself only in that I have eliminated some sideline commentary so that I can add a few thoughts originally intended for the end, when I had talked myself out of time.

A standard sample (SS) of 14C-specific β activity has been created based on benzene containing radioactive carbon diluted with “dead” benzene.

The Suyanggae archeological complex is located in Aegok-li, Danyang County, Chungbuk Province, Korea (128°20'00"E, 365˚7'15"N, elevation 132 m). We investigated two Suyanggae Paleolithic localities (1 and 6). A total of 31 samples (18 localities) were analyzed for radiocarbon (14C) ages in three paleolithic cultural horizons of Suyanggae Locality 6 (SYG-6). The purpose of this paper is to report all dating results of SYG-6. It was found that ranges of 14C ages (BP) of cultural layers of SYG-6 are known to be 17,550 ± 80 ∼ 20,470 ± 70, 30,360 ± 350 ∼ 44,100 ± 1900, and 34,870 ± 540 ∼ 46,360 ± 510 BP for cultural layers 2, 3, and 4, respectively. We compared these age data with those of the previous study associated with Gunang Cave near Suyanggae Locality 1 (SYG-1). Based on the chronological information of the three archaeological sites, early humans lived in a rather cold environment from approximately 30,000 to 46,000 BP and disappeared between 30,000 ∼ 20,000 BP and then settled again in SYG-6 site during LGM period. This study demonstrates that archaeological study is important not only for understanding human occupations with their cultural development but also establishing climatic signals to which they have been adapted as a part of the human evolutional process.

The following date list includes samples processed by the Illinois State Geological Survey Radiocarbon Dating Laboratory from September 1968 through November 1969. Detailed descriptions of sample methods are published elsewhere (Kim and Ruch, 1969; Kim, Ruch, and Kempton, 1969).

B. P. Konstantinov and G. E. Kocharov (1965, 1967) addressed the complex problem of astrophysical phenomena and radiocarbon. Currently available data show that the determination of cosmogenic 14C in accurately dated samples of terrestrial and atmospheric origin is one of the most reliable and promising methods for studying cosmic-ray variations in the past. 14C dating samples of terrestrial origin has helped solve the problem of long-term (100 yr or more) 14C variations and, accordingly, of cosmic-ray variations in the past. Short-term (ca. 11 yr or less) variations are still under investigation (Alexeyev et al. 1971; Damon, Long and Wallick 1973).

The transition from the Middle to Late Pre-Pottery Neolithic B (PPNB) happened throughout southwest Asia in the mid-8th millennium cal BC. It entailed the abandonment of a number of sites, rapid growth of others, as well as the wide spread of morphologically domestic caprines. What remains an unknown is how rapid these processes were in real time. Over the period when the transition was taking place, the calibration curve has two shallow sections divided by a sudden drop, which for many of the older dates creates an illusion of a sudden cultural break around 7600–7500 cal BC. Yet a more detailed study presented in this paper suggests that the transition event could have been spread over a more extended period of time. This, however, is still far from certain due to risks of old wood effects and complexities of site formation.

Jaguariaíva 1 is a sandstone rockshelter located in Jaguariaíva, Paraná State, Brazil, with rock art on the surface of the walls and ceiling. A stratigraphic analysis of the soil within the shelter showed six occupational layers and a superficial disturbed layer with evidence from the end of the 19th century. The establishment of a rock-art chronology became possible using fallen painted rock sections incorporated into three sedimentary levels underlying this rock shelter. These show superimpositions of several pictures of differently sized animals, such as deer, and lattice motifs, which are generally associated with the Planalto rock art tradition. The chronological study was performed based on radiocarbon (14C) analysis of charcoal collected from six excavated subsurface archaeological contexts. The two oldest layers, associated with hunters and gatherers of the Umbu tradition, were dated to 7680–7516 cal BP and 6913–6656 cal BP. There are four occupational layers from ceramists and farmers related to the south Jê linguistic family, and linked to the Itararé-Taquara archaeological tradition: layer 3 linked to the oldest of such occupation, dated to 3058–2796 cal BP, followed by layer 4, dated to 2080–1701 cal BP. Layers 5 and 6, dated to 1995–1526 cal BP and 540–152 cal BP, respectively.

The Laboratory of Applied Nuclear Physics of the Brown Coal Research Institute in Most started the radiocarbon dating of archaeologic samples in 1972. Dates presented in this list were obtained from 1973 to 1974.

El Maye is a community located in the municipality of Ixmiquilpan, Hidalgo, in the central region of Mexico. During the late Postclassic period (1350–1521 AD), the Aztecs controlled the area through the establishment of a dual-headed system, one part belonging to the Aztec government and the other to the local government. El Maye was the local government center for the Ixmiquilpan territory under the Aztec domain. The residential units of El Maye archaeological site were constructed in 6 different occupational phases, with the presence of large rooms, stucco floors and walls, offerings, and a variety of ceramics belonging to the late Aztec III ceramic period (1400–1520 AD). The Axis Project of the Mezquital Valley (PEVM-ENAH) and the Accelerator Mass Spectrometry Laboratory (LEMA-UNAM) have undertaken a collaborative study of the El Maye site by performing absolute radiocarbon accelerator mass spectrometry (14C AMS) dating. For a better understanding of the emergence and development of El Maye, a series of AMS 14C dates of charcoal and bone samples recovered from different stratigraphic levels, was performed. This allowed us to locate the occupation of the site between 1320 and 1625 cal AD.

A number of electronic systems are used on the ANTARES accelerator at ANSTO to implement its fast cycling accelerator mass spectrometry (AMS) capability. The fast cycling system was originally installed and commissioned in 1993 and has recently been updated. This paper describes the more significant of the electronic systems, such as the controller (“sequencer”), the high-voltage power supply (“bouncer”), the fast electrostatic beam chopper, and those used for measurement of the pulsed ion beam current. The sequencer, a programmable 15-bit digital pulse generator, generates the timing and sequencing of the control signals for bouncing voltage selection, beam chopping, Faraday cup current measurement, and rare isotope event measurement. The new sequencer is implemented using a National Instruments FPGA (field programmable gate array) card, programmed using LabVIEW 2010. This device has the benefits of host CPU-independent operation, simple interfacing (PCI), a small footprint, off-the-shelf availability at modest cost, and ease of functionality upgrade. The sequencer provides 15 synchronous digital signals, whose “on” and “off” transitions can be independently specified, in both number and time, with a time resolution of between 0.5 and 128 μs, and with the total duration between repetitions adjustable between 65.5 ms and 8.4 s per cycle. It is hosted by a generic PC because of the low-cost and ubiquity of these. The stand-alone FPGA-based approach ensures that the sequencer determinism is unaffected by processes executing in the host CPU.

The present list contains 14G dates from archaeologic samples attributed to the European Mesolithic period from the typology of associated finds, especially microliths. Of these samples, 14 are from Germany and 6 from France.

A “C14” data base has been created for internal use of 14C dates with an Osborne-1 system. It uses a CP/M operating system, Z-80 CPU, and dBASE II software program. The structure meets the users’ requirements of information and easy retrieval. The video display is quite compact, as a record of 32 fields is edited to fill a screen of 22 lines. A standard printout is edited to make room for two records per page and contains all information from these records. Searching may take place in all fields or parts of fields, in interval(s) in one or more fields and in various combinations of the prescribed methods of searching. A field called KEYWORDS is established to ease search operations. “C14” may be adapted to individual requirements and equipment with small adjustments.

For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar.

The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age).

This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO2 and then for data interpretation.

Estuaries and deltas are crucial zones to better understand the interactions between continents and oceans, and to characterize the mineralization and burial of different sources of organic matter (OM) and their effect on the carbon cycle. In the present study, we focus on the continental shelf of the northwest Mediterranean Sea near the Rhône river delta. Sediment cores were collected and pore waters were sampled at different depths at one station (Station E) located on this shelf. For each layer, measurements of dissolved inorganic carbon concentration (DIC) and its isotopic composition (δ 13C and Δ14C) were conducted and a mixing model was applied to target the original signature of the mineralized OM. The calculated δ 13C signature of the mineralized organic matter is in accordance with previous results with a δ 13COM of marine origin that is not significantly impacted by the terrestrial particulate inputs from the river. The evolution with depth of Δ14C shows two different trends indicating two different Δ14C signatures for the mineralised OM. In the first 15 cm, the mineralized OM is modern with a Δ14COM = 100 ± 17‰ and corresponds to the OM produced during the nuclear period of the last 50 years. Deeper in the sediment, the result is very different with a depleted value Δ14COM = –172 ± 60‰ which corresponds to the pre-nuclear period. In these two cases, the marine substrate was under the influence of the local marine reservoir effect with more extreme Δ14C results. These differences can be largely explained by the influence of the river plume on the local marine DIC during these two periods.

Archaeological investigations of the age and origins of marine shell beads are important for understanding the emergence and maintenance of long-distance trade networks in prehistory. In this paper we expand upon and re-examine the incremental carbon (14C and δ13C) and oxygen (δ18O) isotope data from two Olivella biplicata shell beads from the LSP-1 Rockshelter, Oregon, USA, to address two common problems in dating marine shell trade goods: (1) the source region is large, adding to uncertainty regarding the appropriate specification of ΔR; and (2) the 14C activity within individual specimens is variable. Although this combination of factors severely limits the dating precision that is possible, we recommend a sampling and calibration approach that accounts for these added sources of uncertainty and minimizes the loss of precision. We recommend (1) sequential sampling in order to quantify the range of variability in 14C within shells; (2) a Bayesian calibration procedure that models the 14C dates as an ontogenetic sequence, in this case constrained by stable isotope sclerochronology; and (3) specifying ΔR in a manner that accounts for the full range of possible reservoir offsets in the source region.

In the framework of the interdisciplinary project “Settlement History of the Eastern Sahara” at the Universität zu Köln, a large number of sites were excavated during the 1980s in northern Sudan, where the Laqiya-region with the Wadi Shaw and Wadi Sahal was one of the main research areas. About 150 sites have been surveyed and partly excavated. One of these sites, Wadi Shaw 82/52, yielded sherds of a Maidum bowl, which is dateable to the Egyptian IVth and Vth Dynasty. This site was dated by four radiocarbon dates. The dates are compared with the historical chronology of Egypt for the IVth and Vth Dynasty, and are shown to be in good agreement.

We investigated the dolmen known as Kolikho (Black Sea coast, Russia), discovered accidentally in 2008. It is a unique, undisturbed megalithic structure. The burial chamber contains disarticulated human remains from about 70 individuals. Radiocarbon dating shows that the dolmen was in use between roughly the 19th to 13th centuries BC. Strontium isotopes are used to investigate the origin and last residence location of the people buried in the structure.