Radiocarbon evidence for the pace of the M-/L-PPNB transition in the 8th millennium BC south-west Asia

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

Exploring site formation and building local contexts through wiggle-match radiocarbon dating: re-dating of the Firth of Clyde Crannogs, Scotland

There are at least four wooden intertidal platforms, also known as marine crannogs, in the Firth of Clyde, on the west coast of Scotland. The interpretation of these sites partly depends on their dating and, if coeval, they could point to the presence of a native maritime hub. Furthermore, the spatial coincidence with the terminus of the Antonine Wall has led to speculation about the role they may have played in Roman-native interaction during the occupation of southern Scotland in the early first millennium cal ad. Hence, a better absolute chronology is essential to evaluate whether the marine crannogs were contemporary with one another and whether they related to any known historic events. This article presents results of a wiggle-match dating project aimed at resolving these uncertainties at two of the sites in question, Dumbuck and Erskine Bridge crannogs. The results show that the construction of these sites pre-date direct Roman influence in Scotland. Furthermore, the results indicate that the two sites were built at least 300 years apart, forcing us to consider the possibility that they may have functioned in very different historical contexts. Other findings include technical observations on the fine shape of the radiocarbon calibration curve near the turn of the first millennia bc/ad and potential evidence for persistent contamination in decayed and exposed sections of waterlogged alder

Improving the 14C dating of south-west Scottish wetland sites

This thesis discusses the adaptation of the wiggle-match dating technique and Bayesian chronological models to the practicalities of dating timbers from Iron Age Scottish wetland sites, with a focus on the area between the firths of the rivers Clyde and Solway. Wiggle-match dating technique relies on taking measurements from a sequence with an estimated, or known deposition rate, such as timbers, and fitting the resultant time series to an established calibration curve. Bayesian modelling entails combining various forms of information about the material dated to obtain a more comprehensive chronological understanding. These techniques are relevant to Iron Age wetland settlement in Scotland due to the lack of other methods that could produce high-precision dates on a routine basis; too few timbers from Scottish wetlands produce absolute dendrochronological dates and ordinary radiocarbon calibrations tend to have low precision during the period 750-200 BC, which covers the formative stages of both the Scottish Iron Age and wetland settlement tradition. Effective use of the wiggle-match dating technique requires attention to aspects of technique, its practical implementation and suitable research design. As far as technical aspects are concerned, the work conducted within this thesis demonstrated the need to match the length of sample blocks of wood with the length of the measurements underpinning the calibration curve. Furthermore, presence of small offsets between the calibration curve and the actual past trend of radiocarbon has been identified; while these offsets have minimal impact on most radiocarbon applications, the wiggle-match dating technique is sensitive to them and hence conscious decisions need to be made at the stage of research design to avoid systematic bias in the results. Aspects of practical implementation have been explored through wiggle-match dating studies at four sites: Black Loch of Myrton, Cults Loch 3, Dumbuck and Erskine Crannog. Results demonstrate that even on the most challenging parts of the calibration curve wiggle-match dating can succeed in producing modelled date ranges of less than 100 years and that, on more favourable parts of the curve, it can be used to aid the resolution of questions regarding site formation processes. Moreover, these case studies highlighted a number of practical issues such as propensity of decayed rings to produce radiocarbon results biased towards older ages. Efficient use of wiggle-match dating in archaeological contexts requires not only the technical and practical capacity, but also a strategic framework within which the methodology is to be employed. While the nature of this framework depends on the interpretations the researcher is interested in, this thesis suggests a focus on developing linkage between different sites, both wetland and terrestrial, so that the well-preserved deposits become informative of not only a single site, but also shed light on the local and regional developments

Challenges and prospects for building radiocarbon chronologies of the earlier Holocene of the Levant

This paper explores the challenges of building radiocarbon chronologies of the earlier Holocene of South-West Asia. The analysis consists of a technical and a taphonomic review of a selection of the published 14C record, followed by a modelling study of a sub-section of that data. This sketches the kinds of chronological syntheses we can hope to construct, given the nature of the sites in the region. The key observation from the review of individual radiocarbon determinations is that reliable radiocarbon dating contexts are very limited. This is due to taphonomic ambiguity associated with charred plant remains and the persisting difficulties in dating skeletal remains from South-West Asia. The modelling study highlights the challenges of tracing events, such as site onset and abandonment, on complex, long-lived sites, and the large extent of chronological ambiguity stemming, to a large extent, from the taphonomic challenges. Many of these issues might be resolved through new 14C extraction techniques, the ongoing improvement of excavation methods, as well as rethinking chronological syntheses with a greater focus on relationships between specific contexts

Radiocarbon wiggle-match dating in the intertidal zone

Radiocarbon wiggle-match dating is a technique that can combine the versatility of radiocarbon dating with chronological information from tree-rings. This makes it useful in contexts where timbers are preserved, but dendrochronological dating is impossible. As intertidal and marine timbers are waterlogged, this can favor their preservation and hence allow wiggle-match 14C dating, which can be of significant help in deriving relatively precise chronologies for a range of coastal structures. As the technique depends on making multiple radiocarbon measurements towards a single date, efficiency in application is the key and hence a number of practical considerations need to be taken into account in advance of conducting a dating program. This paper discusses some of these practical concerns and reviews them in the context of the intertidal crannogs in the Firth of Clyde on the west coast of Scotland

Radiocarbon releases from the 2011 Fukushima nuclear accident

Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees (Cryptomeria japonica) collected at six sites ranging from 2.5–38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The 14C specific activity varied from 280.4 Bq kg−1 C in 2010 to 226.0 Bq kg−1 C in 2015. The elevated 14C activities in the 2009 and 2010 rings confirmed 14C discharges during routine reactor operations, whereas those activities that were indistinguishable from background in 2012–2015 coincided with the permanent shutdown of the reactors after the accident in 2011. High-resolution 14C analysis of the 2011 ring indicated 14C releases during the Fukushima accident. The resulted 14C activity decreased with increasing distance from the plant. The maximum 14C activity released during the period of the accident was measured 42.4 Bq kg−1 C above the natural ambient 14C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the 14C released during the accident is indistinguishable from ambient background beyond the local environment (~30 km from the plant). Furthermore, the resulting dose to the local population from the excess 14C activities is negligible compared to the dose from natural/nuclear weapons sources

Measurement of inclusive π0\pi^{0} production in hadronic Z0Z^{0} decays

An analysis is presented of inclusive \pi^0 production in Z^0 decays measured with the DELPHI detector. At low energies, \pi^0 decays are reconstructed by \linebreak using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to x_p = 2 \cdot p_{\pi}/\sqrt{s} = 0.75) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for {q\overline q} and {b \bar b} events. The number of \pi^0's per hadronic Z^0 event is N(\pi^0)/ Z_{had}^0 = 9.2 \pm 0.2 \mbox{(stat)} \pm 1.0 \mbox{(syst)} and for {b \bar b}~events the number of \pi^0's is {\mathrm N(\pi^0)/ b \overline b} = 10.1 \pm 0.4 \mbox{(stat)} \pm 1.1 \mbox{(syst)} . The ratio of the number of \pi^0's in b \overline b events to hadronic Z^0 events is less affected by the systematic errors and is found to be 1.09 \pm 0.05 \pm 0.01. The measured \pi^0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the \mathrm \xi_p = \ln(1/x_p) distribution is \xi_p^{\star} = 3.90^{+0.24}_{-0.14}. The average number of \pi^0's from the decay of primary \mathrm B hadrons is found to be {\mathrm N} (B \rightarrow \pi^0 \, X)/\mbox{B hadron} = 2.78 \pm 0.15 \mbox{(stat)} \pm 0.60 \mbox{(syst)}

Measurements of the leptonic branching fractions of the τ\tau

Data collected with the DELPHI detector from 1993 to 1995 combined with previous DELPHI results for data from 1991 and 1992 yield the branching fractions B({\tau \rightarrow \mbox{\rm e} \nu \bar{\nu}}) = (17.877 \pm 0.109_{stat} \pm 0.110_{sys} )\% and $B({\tau \rightarrow \mu \nu \bar{\nu}}) = (17.325 \pm 0.095_{stat} \pm 0.077_{sys} )\%$