scholarly journals Development of single grain OSL dating of ceramic materials: Spatially resolved measurement of absorbed dose

2006 ◽  
Vol 41 (7-8) ◽  
pp. 744-749 ◽  
Author(s):  
I.K. Bailiff
Keyword(s):  
Absorbed Dose ◽  
Ceramic Materials ◽  
Osl Dating ◽  
Spatially Resolved ◽  
Single Grain

scholarly journals Towards an improvement of optically stimulated luminescence (OSL) age uncertainties: modelling OSL ages with systematic errors, stratigraphic constraints and radiocarbon ages using the R package BayLum

Geochronology ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 229-245
Author(s):  
Guillaume Guérin ◽  
Christelle Lahaye ◽  
Maryam Heydari ◽  
Martin Autzen ◽  
Jan-Pieter Buylaert ◽  
...  
Keyword(s):  
R Package ◽  
Systematic Errors ◽  
Covariance Matrices ◽  
Optically Stimulated Luminescence ◽  
Osl Dating ◽  
Dose Rates ◽  
Determination Procedure ◽  
Single Grain ◽  
Measurement Uncertainties ◽  
Osl Age

Abstract. Statistical analysis has become increasingly important in optically stimulated luminescence (OSL) dating since it has become possible to measure signals at the single-grain scale. The accuracy of large chronological datasets can benefit from the inclusion, in chronological modelling, of stratigraphic constraints and shared systematic errors. Recently, a number of Bayesian models have been developed for OSL age calculation; the R package “BayLum” presented herein allows different models of this type to be implemented, particularly for samples in stratigraphic order which share systematic errors. We first show how to introduce stratigraphic constraints in BayLum; then, we focus on the construction, based on measurement uncertainties, of dose covariance matrices to account for systematic errors specific to OSL dating. The nature (systematic versus random) of errors affecting OSL ages is discussed, based – as an example – on the dose rate determination procedure at the IRAMAT-CRP2A laboratory (Bordeaux). The effects of the stratigraphic constraints and dose covariance matrices are illustrated on example datasets. In particular, the benefit of combining the modelling of systematic errors with independent ages, unaffected by these errors, is demonstrated. Finally, we discuss other common ways of estimating dose rates and how they may be taken into account in the covariance matrix by other potential users and laboratories. Test datasets are provided as a Supplement to the reader, together with an R markdown tutorial allowing the reproduction of all calculations and figures presented in this study.

Spatially resolved observation of charge transfer across single grain boundaries in YBaCuO films

Cryogenics ◽  
1990 ◽  
Vol 30 (5) ◽  
pp. 397-400 ◽  
Author(s):  
J. Mannhart ◽  
R. Gross ◽  
R.P. Huebener ◽  
P. Chaudhari ◽  
D. Dlmos ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Grain Boundaries ◽  
Spatially Resolved ◽  
Single Grain

Insight into the sediment dynamics of a high-impact low-frequency mass movement event using single-grain feldspar luminescence in the Pokhara valley, Nepal

2021 ◽  
Author(s):  
Anna-Maartje de Boer ◽  
Wolfgang Schwanghart ◽  
Jürgen Mey ◽  
Jakob Wallinga ◽  
Basanta Raj Adhikari ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Mass Movement ◽  
Low Frequency ◽  
High Impact ◽  
Osl Dating ◽  
Transport Dynamics ◽  
Infrared Stimulated Luminescence ◽  
Single Grain ◽  
Pokhara Valley ◽  
Insight Into

<p>Mass movements play an important role in landscape evolution of high mountain areas such as the Himalayas. Yet, establishing numerical age control and reconstructing transport dynamics of past events is challenging. To fill this research gap, we investigated the potential of Optically Stimulated Luminescence (OSL) dating and tracing methods. OSL dating analyses of Himalayan sediments is extremely challenging due to two main reasons: i) the OSL sensitivity of quartz, typically the mineral of choice for dating sediments younger than 100 ka, is poor, and ii) highly turbid conditions during mass movement transport hamper sufficient OSL signal resetting prior to deposition which eventually results in age overestimation. In this study, we aim to bring OSL dating to the test in an extremely challenging environment. First, we assess the applicability of single-grain feldspar dating of mass movement deposits in the Pokhara valley, Nepal. Second, we exploit the poor bleaching mechanisms to get insight into the sediment dynamics of this paleo-mass movement through bleaching proxies. The Pokhara valley is a unique setting for our case-study, considering the availability of an extensive independent radiocarbon dataset (Schwanghart et al., 2016) as a geochronological benchmark.</p><p>Single-grain infrared stimulated luminescence signals were measured at 50°C (IRSL50) and post-infrared infrared stimulated luminescence signals at 150°C (pIRIR-150). As expected, results show that the IRSL50 signal is better bleached than the pIRIR150 signal. A bootstrapped Minimum Age Model (bMAM) is applied to retrieve the youngest subpopulation to estimate the palaeodose. However, burial ages calculated based on this palaeodose overestimate the radiocarbon ages by an average factor of ~8 (IRSL50) and ~35 (pIRIR150). This shows that dating of the Pokhara Formation with our single-grain approach was not successful. Large inheritances in combination with the scatter in the single-grain dose distributions show that the sediments have been transported prior to deposition under extreme limited light exposure which corresponds well with the highly turbid nature of the sediment laden flood and debris flows that emplaced the Pokhara Formation.</p><p>To investigate the sediment transport dynamics in more detail we studied three bleaching proxies: the percentage of grains in saturation (2D0 criteria), percentage of well-bleached grains (2σ range of bMAM-De) and the overdispersion (OD). Neither of the three bleaching proxies indicate a spatial relationship with run-out distances of the mass movement deposits. We interpret this as virtual absence of bleaching during transport, which reflects the catastrophic nature of the event. While single-grain feldspar dating did not provide reliable burial ages of the Pokhara mass movement deposits, our approach has great potential to provide insight in sediment transport dynamics of high-impact low-frequency mass movement events in mountainous region.</p><p><em>References</em></p><p>Schwanghart, W., Bernhardt, A., Stolle, A., Hoelzmann, P., Adhikari, B. R., Andermann, C., ... & Korup, O. (2016). Repeated catastrophic valley infill following medieval earthquakes in the Nepal Himalaya. Science, 351(6269), 147-150.</p>

Towards Selective Volumetric Additive Manufacturing and Processing of Ceramics

2019 ◽  
Author(s):  
A. P. Iliopoulos ◽  
J. G. Michopoulos ◽  
J. C. Steuben ◽  
A. J. Birnbaum ◽  
B. D. Graber ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Ceramic Powder ◽  
Ceramic Materials ◽  
High Quality ◽  
Analysis And Design ◽  
Spatially Resolved ◽  
Selective Approach ◽  
Scientists And Engineers ◽  
Processing Techniques ◽  
Am Processes

Abstract The development of advanced additive manufacturing (AM) and material processing techniques is currently a topic of great interest to broad communities of scientists and engineers. In particular, there is a need for AM processes capable of producing functional and high-quality components at a faster rate than is currently achievable. In response to this demand, the present work introduces the initial steps of a novel spatially-resolved and selective approach for processing volumetric regions of ceramic materials. The proposed method utilizes microwave radiation to heat material at desired locations within a domain filled with ceramic powder. Using this principle of operation, a number of methods for implementation of this process are proposed. As a first step, a multiphysics computational methodology and an associated model that allows for the analysis and design of relevant processing systems is introduced. Additionally, a number of simulations demonstrating the feasibility of the proposed methodology are presented. Based on these preliminary results, we conclude with a discussion of ongoing and future efforts to fully realize this technology.

scholarly journals Comparative Study of Natural Radioactivity and Radiological Hazard Parameters of Various Imported Tiles Used for Decoration in Sudan

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 746 ◽  
Author(s):  
Saifeldin Siddeeg ◽  
Mohamed Suliman ◽  
Faouzi Ben Rebah ◽  
Wissem Mnif ◽  
Amel Ahmed ◽  
...  
Keyword(s):  
Natural Radioactivity ◽  
Hazard Index ◽  
Absorbed Dose ◽  
Ceramic Materials ◽  
Radiological Hazard ◽  
Absorbed Dose Rate ◽  
Mean Values ◽  
Activity Concentrations ◽  
Materials Used ◽  
Hazard Parameters

Various commercially imported ceramic materials used in the building of Sudanese dwellings were examined in order to determine their natural radioactivity and radiological hazard parameters. In this context, twenty-five different consignments were sampled and analyzed using (3″ × 3″) sodium iodide gamma spectrometry system NaI(Tl). The identified average activity concentrations of 238U, 232Th, and 40K were 183 ± 70, 51 ± 44, and 238 ± 77 Bq/kg dry-weights, respectively. A positive correlation between 238U and 232Th in the investigated samples was identified from the observed significant correlation (R2 = 0.8). Interestingly, a low Th/U ratio (~0.3) was recorded, which could be related to the systematic loss of thorium during the fabrication process. The measured activity concentrations for these radionuclides were comparable with the reported data obtained from similar materials used in other countries showing similarity in ceramic materials used in buildings. Five different radiation indices, such as the average radium equivalent (Raeq), the absorbed dose rate (D), the annual effective dose equivalent (AEDE), the external hazard index (Hex), and the radioactivity level index (lγ), which indicate hazardous radiation, were estimated from these measurements. The obtained results revealed average values of 274 ± 106 Bq/kg, 125 ± 48 nGy/h, 1.23 ± 0.48 mSv/y, 0.74 ± 0.29, and 0.94 ± 0.37, for Raeq, D, AEDE, Hex, and lγ, respectively. The mean values of Raeq and Hex were in good agreement with the international limits, while the means of D and lγ were higher than the universal values. Calculated AEDE in about 60% of the samples exceeded the universal limit of 1 mSv/y for the public exposure (maximum value of 2.16 mSv/y). The investigated parameters were in the same range for the majority of imported samples; however, they were slightly higher than the locally produced ceramic, highlighting the importance of monitoring imported materials for their radioactivity contents.

Single-grain OSL dating of the Howiesons Poort layers at Klipdrift Shelter, Southern Cape, South Africa

2016 ◽  
Vol 404 ◽  
pp. 199
Author(s):  
S. Armitage ◽  
C.S. Henshilwood ◽  
K.L. van Niekerk
Keyword(s):  
South Africa ◽  
Osl Dating ◽  
Single Grain

scholarly journals Expectations of scatter in equivalent-dose distributions when using multi-grain aliquots for OSL dating

2011 ◽  
Vol 38 (4) ◽  
pp. 424-431 ◽  
Author(s):  
Alastair Cunningham ◽  
Jakob Wallinga ◽  
Philip Minderhoud
Keyword(s):  
Dose Rate ◽  
Equivalent Dose ◽  
Osl Dating ◽  
Dose Distributions ◽  
Sensitivity Distribution ◽  
Minimum Age ◽  
Single Grain ◽  
Counting Statistics ◽  
Partial Bleaching

AbstractIn the OSL dating of sediment, the scatter in equivalent dose (D e) between grains is almost always larger than would be expected due to counting statistics alone. Some scatter may be caused by insufficient (partial) bleaching of some of the grains prior to deposition. In order to date partially bleached sediment, it is essential to estimate the amount of scatter caused by other processes (e.g. grain-to-grain variability in the natural dose rate). Measurements of such scatter are performed at the single-grain level; by contrast, most OSL dating is performed on multi-grain subsamples, for which grain-to-grain scatter is reduced through averaging.Here we provide a model for estimating the expected scatter (i.e. excluding that caused by partial bleaching) for multi-grain aliquots. The model requires as input the single-grain sensitivity distribution, the number of grains in the sub-samples, and the expected scatter at the single-grain level, all of which can be estimated to an adequate degree. The model compares well with measured values of scatter in D e, determined using aliquots of various sizes, and can be used to help produce a minimum-age D e from multi-grain subsamples that is consistent with single-grain data.

Modeling incomplete and heterogeneous bleaching of mobile grains partially exposed to the light: Towards a new tool for single grain OSL dating of poorly bleached mortars

2017 ◽  
Vol 107 ◽  
pp. 48-57 ◽  
Author(s):  
Pierre Guibert ◽  
Claire Christophe ◽  
Petra Urbanová ◽  
Guillaume Guérin ◽  
Sophie Blain
Keyword(s):  
Osl Dating ◽  
Single Grain
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