Grzegorz Adamiec

OSL properties of NaCl relative to dating and dosimetry

Abstract The luminescence properties of NaCl are discussed. Attention is focussed predominantly upon the optically stimulated luminescence (OSL) signal (UV emission) of NaCl (420–560 nm stimulation). The results from experiments relevant to geological dating applications, such as signal resetting, dose response and thermal stability, are described. The behaviour of the OSL signal observed was found to be favourable for dating, with both the thermal stability and dose response suggesting a range of at least 10 ka. Signal resetting via optical exposure was found to be extremely rapid and no evidence of either thermoluminescence or OSL signals was found following re-crystallization. The potential for dating natural salt deposits, as found in various arid environments, appears to be good.

The mechanism of thermally transferred optically stimulated luminescence in quartz

In this paper we assess two mechanisms for the production of the thermally transferred optically stimulated luminescence (TT-OSL) signal in quartz when all stimulation is carried out at 125 °C. One mechanism is based on the double transfer process previously put forward for OSL recuperation following storage at room temperature. In this mechanism, electrons from the trap giving rise to the fast OSL component are released by optical stimulation and some are transferred into a refuge trap via the conduction band; these electrons are then released from the refuge trap by a thermal treatment and some are retrapped in the trap responsible for the fast OSL component. The other mechanism is based on a single transfer process in which electrons are transferred by thermal treatment from a light-sensitive trap via the conduction band to the trap that gives rise to the fast component of the OSL signal, this trap having been emptied by the initial optical stimulation. The analysis of the measured OSL and TT-OSL decay curves suggest that the two signals are derived from the same traps and are dominated by the fast OSL component. The experimental data presented support the hypothesis that the original source of the electrons that are thermally transferred is a trap that is less light sensitive than that giving rise to the fast OSL, but one that has similar thermal stability. Thus, a single transfer mechanism explains the production of the TT-OSL signal observed for stimulation above 120 °C when the 110 °C TL trap is kept empty.

Variations in luminescence properties of single quartz grains and their consequences for equivalent dose estimation

In this paper examples of variability of luminescence properties between single grains of quartz extracted from natural samples or from crushed single crystals are shown. It is demonstrated how measurements of glow curves, PSL (photon stimulated luminescence) decay curves, thermal activation characteristics using multi-grain aliquots can lead to a misinterpretation of the obtained data. The possible consequences for different DE estimation techniques applied to multi-grain aliquots or to single grains and normalisation techniques applied to multi-grain aliquots are discussed. In particular pre-dose, multi-aliquot additive, and single grain PSL SAR DE estimation methods are considered.

The new 14C analysis laboratory in Jena, Germany

The new accelerator mass spectrometry (AMS) Radiocarbon Analysis Laboratory in Jena is described. The laboratory developed a combustion system for solid samples and a CO (sub 2) extraction system for air samples. Thus far, sample preparation, including graphitization, was performed in the laboratory, and the samples were measured subsequently by other AMS facilities. Currently, the laboratory owns a 3MV AMS system from HVEE (Netherlands) that has passed the acceptance tests and will be used for routine (super 14) C determinations in the near future. The AMS system is equipped with 2 ion sources, one suitable for graphite targets and the second for both graphite and CO (sub 2) targets.

OSL dating and lithological characteristics of loess deposits from Biały Kościół

Absolute dating using luminescence methods is widely applicable in geology, geomorphology, palaeogeography and in archaeology in establishing ages of sediments and archaeological artefacts. By creating absolute time scales for different events in the history of Earth scientists are able to reconstruct changes in climate and environment in the past, and the history of colonization and development of culture.Grain size is the most important loess lithologic property. Grain size composition depends mainly on factors connected with depositional processes (i.e. variety of source areas, distance from source areas, frequency and intensity of dust transporting winds). The influence of post depositional processes on changes in grain size composition seems to be of less importance with the exceptions for warm and long periods of intensive pedogenesis, which are favorable for formation of clay minerals. Therefore the grain size differentiation within thick loess sections may be used as a proxy record of climate changes during loess cover development.Here we present results for 12 samples dated at the profile at Biały Kościół. Obtained OSL results in some cases are quite different as compared with the OSL and TL dates obtained during last 10 years by other authors and presented in previous publications relating to this loess profile.

A new technique in retrospective TL dosimetry: Pre-dose effect in the 230°C TL glow peak of porcelain

Abstract We have observed that the 230°C TL glow peak in porcelain possesses the same pre-dose properties as the 110°C TL glow peak in quartz. The pre-dose effect is the increase in TL radiation sensitivity observed after irradiation and subsequent heating of quartz and the increase is proportional to the total absorbed radiation dose prior to heating. It is a useful technique in dating and authentication of art objects as well as in retrospective dosimetry after radiation accidents. The disadvantage of the 110°C pre-dose peak is that it rapidly becomes non-linear and can only be used for doses less than 1 Gy. Porcelain contains quartz and exhibits both the 110°C TL glow peak and a peak at 230°C. Both peaks are observed to have approximately the same amplitude when using narrow band blue filters. The thermal activation properties, radiation dose response and dosimetric applicability of 230°C pre-dose TL glow peak of porcelain were investigated, and we found that it has the same TL properties as the 110°C peak but has advantages for dose evaluation due to its longer half-life and linearity up to a dose of 3 Gy.

Absolute chronology of fluvial events in the Upper Dnieper River system and its palaeogeographic implications

A set of 121 radiocarbon and OSL dates has been compiled from the Upper Dnieper River and tributary valleys, Western European Russia. Each date was attributed according to geomorphic/sedimentological events and classes of fluvial activity. Summed probability density functions for each class were used to establish phases of increasing and reducing fluvial activity. The oldest detected reduction of fluvial activity was probably due to glacial damming at LGM. Within the Holocene three palaeohydrological epochs of millennial-scale were found: (1) high activity at 12,000–8,000 cal BP marked by large river palaeochannels; (2) low activity at 8,000–3,000 cal BP marked by formation of zonal-type soils on -floodplains; short episodes of high floods occurred between 6,500—4,400 cal BP; (3) contrasting hydrological oscillations since 3,000 cal BP with periods of high floods between 3,000–2,300 (2,000) and 900–100 cal BP separated by long interval of low floods 2,300 (2,000)-900 cal BP when floodplains were not inundated — zonal-type soils were developing and permanent settlements existed on floodplains. In the last millennium, four centennial-scale intervals were found: high flooding intervals are mid-11–mid-15th century and mid-17–mid-20th century. Intervals of flood activity similar to the present-day were: mid-15–mid-17th century and since mid-19th century till present. In the context of palaeohydrological changes, discussed are selected palaeogeographic issues such as: position of the glacial boundary at LGM, role of changing amounts of river runoff in the Black Sea level changes, floodplain occupation by Early Medieval population.

Optical dating and sedimentary record from the terrace depositional profile of the Warta River (Central Poland)

Results of OSL dating and sedimentary studies from the profile of the low alluvial terrace of the middle Warta River are presented. The samples were dated using the single-aliquot regenera-tive method. Dating was used to establish a timing of the Weichselian Late Glacial events in the river valley environment. Stable conditions on the floodplain are expressed by the deposition of organic-rich series radiocarbon dated at 12 900-12 600 cal BP and 11 600-10 770 cal BP. Samples for OSL dating were collected from the mineral material deposited during the intensification of flood events during the Weichselian decline. The results obtained for the alluvia range from 12.78 ± 0.62 ka b2k to 14.33 ± 0.74 ka b2k. Sedimentological criteria allowed to distinguish between particular flood events. Overestimation of OSL ages is probably a result of rapidity of environmental changes in that time.

Participation of the R-centres in the sensitization of the OSL signal

The evolution of novel procedures for the evaluation of equivalent dose using the optically stimulated luminescence (OSL) signal of quartz became necessary to address (i) the sensitization experienced by the signal during the pre-heat treatment and (ii) the in situ sensitization occurring in nature. The pre-dose phenomena of the OSL and 110 °C TL pre-dose emissions have been reported to be similar. In light of this observation, an attempt has been made in this paper to visualize the role of R-centres in the sensitization process of the OSL emission. The results, based on the experimental observations and kinetics considerations of R-centres, confirm that the R-centres participate in the sensitization process of this signal.

Accident dose estimation using porcelain. A comparison between different thermoluminescence methods

Abstract Accident dose estimation using the pre-dose technique on the 100°C peak in porcelain has been used since 1984. The disadvantage of this technique is that the reservoir traps appear to begin to saturate for doses around 1 Gy. This has limitations in regions of high fallout doses such as the contaminated settlements in the Chernobyl Exclusion Zone with fallout doses often above 1 Gy. When doses are added to measure the growth curve the total absorbed dose falls into the saturation region. Samples of porcelain fitments were collected from such settlements and it was observed that the 230°C peak in the thermoluminescence (TL) glow-curve for some of them was strong enough to carry out the simple additive dose procedure. In addition, the 230°C peak pre-doses in a similar way. This enabled us to carry out three dose evaluations on each sample. It was observed that both pre-dose evaluations yielded a similar result. The results of the simple additive dose in most cases are in agreement within error limits with the results obtained using pre-dose techniques, although in some cases some discrepancies were observed.