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Abstract Previous work has demonstrated the feasibility of performing spatially resolved luminescence measurements with sliced solid materials (e.g., rock and ceramic) to determine the cumulative absorbed dose to individual luminescent grains in situ. In the present study, aspects of the dosimetry of individual grains that are truncated during slicing were examined using radiation transport simulations employing simplified geometries. The results of the simulations were applied to model the effect of grain truncation on the dosimetry of grains, in particular the beta attenuation factor and the laboratory beta source dose rate for whole and partial volumes of individual spherical grains. Where a material contains a wide range of coarse grain sizes there is the potential for misinterpreting the size of the parent grain on the basis of an examination of the shape and size of the truncated grain section exposed in the slice surface. If the original grain size is underestimated, which is likely, the simulations predict an overestimation of both the beta attenuation factor and the laboratory source beta dose rate, the maximum extent of which depends on the range of grain sizes present in the material. The simulations also indicate that by limiting the depth from the surface within which the average absorbed dose is determined, approximating the effects of opacity of the mineral, the magnitude of these deviations is reduced. However, a consequence of particular interest deriving from these results is that, when evaluating the age equation, the changes in the two quantities compensate, acting to moderate the overall effect on the calculated age for an individual grain, depending on the geometry of the grain and the composition of the sample material. Highlights • This study examined an aspect of in situ single grain dating of minerals within sliced solid samples. • Grain truncation potentially affects values of both the beta attenuation factor and the laboratory beta source dose rate. • Radiation transport simulations were used to examine the effect of grain truncation on beta dose rate assessment. [ABSTRACT FROM AUTHOR]

This paper reviews recent research on the application of the physical dosimetry techniques of electron paramagnetic resonance (EPR) and luminescence (optically stimulated luminescence, OSL, and thermoluminescence, TL) to determine radiation dose following catastrophic, large-scale radiological events. Such data are used in dose reconstruction to obtain estimates of dose due to the exposure to external sources of radiation, primarily gamma radiation, by individual members of the public and by populations. The EPR and luminescence techniques have been applied to a wide range of radiological studies, including nuclear bomb detonation (e.g., Hiroshima and Nagasaki), nuclear power plant accidents (e.g., Chernobyl), radioactive pollution (e.g., Mayak plutonium facility), and in the future could include terrorist events involving the dispersal of radioactive materials. In this review we examine the application of these techniques in ‘emergency’ and ‘retrospective’ modes of operation that are conducted on two distinct timescales. For emergency dosimetry immediate action to evaluate dose to individuals following radiation exposure is required to assess deterministic biological effects and to enable rapid medical triage. Retrospective dosimetry, on the other hand, contributes to the reconstruction of doses to populations and individuals following external exposure, and contributes to the long-term study of stochastic processes and the consequential epidemiological effects. Although internal exposure, via ingestion of radionuclides for example, can be a potentially significant contributor to dose, this review is confined to those dose components arising from exposure to external radiation, which in most studies is gamma radiation. The nascent emergency dosimetry measurement techniques aim to perform direct dose evaluations for individuals who, as members of the public, are most unlikely to be carrying a dosimeter issued for radiation monitoring purposes in the event of a radiation incident. Hence attention has focused on biological or physical materials they may have in their possession that could be used as surrogate dosimeters. For EPR measurements, in particular, this includes material within the body (such as bone or tooth biopsy) requiring invasive procedures, but also materials collected non-invasively (such as clippings taken from finger- or toenails) and artefacts within their personal belongings (such as electronic devices of which smart phones are the most common). For luminescence measurements, attention has also focused on components within electronic devices, including smartphones, and a wide range of other personal belongings such as paper and other polymer-based materials (including currency, clothing, bank cards, etc .). The paper reviews progress made using both EPR and luminescence techniques, along with their current limitations. For the longer-established approach of retrospective dosimetry, luminescence has been the most extensively applied method and, by employing minerals found in construction materials, it consequently is employed in dosimetry using structures within the environment. Recent developments in its application to large-scale radiation releases are discussed, including the atomic bomb detonations at Hiroshima and Nagasaki, fallout from the Chernobyl reactor and atmospheric nuclear bomb tests within the Semipalatinsk Nuclear Test Site and fluvially transported pollution within the Techa River basin due to releases from the Mayak facility. The developments made in applying OSL and TL techniques are discussed in the context of these applications. EPR measurements with teeth have also provided benchmark values to test the dosimetry models used for Chernobyl liquidators (clean-up workers), residents of Semipalatinsk Nuclear Tests Sites and inhabitants of the Techa River basin. For both emergency and retrospective dosimetry applications, computational techniques employing radiation transport simulations based on Monte Carlo code form an essential component in the application of dose determinations by EPR and OSL to dose reconstruction problems. We include in the review examples where the translation from the physical quantity of cumulative dose determined in the sampled medium to a dose quantity that can be applied in the reconstruction of dose to individuals and/or populations; these take into account the source terms, release patterns and the movements of people in the affected areas. One role for retrospective luminescence dosimetry has been to provide benchmark dose determinations for testing the models employed in dose reconstruction for exposed populations, notably at Hiroshima and Nagasaki. The discussion is framed within the context of the well-known radiation incidents mentioned above. [ABSTRACT FROM AUTHOR]

Polycrystalline alumina (Al 2 O 3 ) substrates, found in many electronic devices and proposed as dosemeters in emergency situations, were invstigated using a scanning electron microscope (SEM) equipped with cathodoluminescence (CL) and elemental analysis probes. The characteristics of the CL spectra, surface morphology, and impurity content of the Al 2 O 3 substrates were examined and compared with those of single crystal dosimetry-grade Al 2 O 3 :C. Whereas the CL spectrum, measured from 250 to 800 nm, for the Al 2 O 3 :C, contained resolved bands located at ∼340 nm and at ∼410 nm, the spectrum measured with the Al 2 O 3 substrate was significantly broader, extending from ∼250 to ∼450 nm, and also included a narrow band at 695 nm. While it is likely that the accepted model of recombination at F + (∼340 nm) and F (∼410 nm) in Al 2 O 3 :C also applies to the substrate, it is suggested that the presence of impurities within the alumina give rise to additional recombination centres. The 695 nm emission has been assigned to a Cr 3+ ion impurity in previous work on alumina and a band indicated at ∼300 nm may be associated with Mg 2+ or Ca 2+ , the presence of which was confirmed by elemental mapping. Comparison of the spatial distribution of CL with the surface morphology and elemental composition of the samples indicates that the components of the emission spectrum can be qualitatively correlated with impurity content and morphological features of the samples. [ABSTRACT FROM AUTHOR]

Abstract: An experimental intercomparison was performed with brick samples from an early medieval building in the west of France, the St-Philbert-de-Grandlieu abbey. A potentially complex set of microdosimetric problems emerged from characterisation measurements, providing a robust test of the routine procedures used by each laboratory. The dating results obtained using quartz coarse grains and fine grain samples span over a large period of time, exhibiting overdispersion, and where systematic deviations appear between quartz and fine grain chronologies. Factors causing such scatter are analysed in detail, including internal radioactivity of quartz grains, millimetre-scale heterogeneity in the fabric, and the observation and modelling of fading behaviour of fine grain minerals. [Copyright &y& Elsevier]

Abstract: A reference database is described that converts values of cumulative absorbed dose due to radioactive fallout, determined with samples of brick from buildings using the luminescence method, to be converted to kerma in air in a form suitable for use in dose reconstruction. This avoids the need to resort to specialised Monte Carlo (MC) programming techniques for each application. A simple model, used as the basis for MC simulations, comprised a brick building with one wall facing ground contaminated with radioactive fallout where the soil below ground level was divided into 409 source volume elements, extending in total up to 200m from the wall and to a depth of 30cm. MC simulations of the transport of gamma rays from sources of energy 662keV (137Cs) in the soil were performed using the code MCNP 5 to obtain the values of coefficients that quantify the relationship between the specific activity within each source volume and the absorbed dose in a selected ‘detector’ volume of brick within the wall, referred to as the dose coefficient. A program, operating in conjunction with Microsoft Excel, employs additional code to control the movement of data stored in the database and the Excel user interface, enabling the coefficients to be calculated for a specified pattern of sources within the ground. Using these coefficients, the program calculates conversion and correction factors for the user-specified distribution of source activity. Examples of application are presented. [Copyright &y& Elsevier]

Abstract: The feasibility of using an OSL scanning technique to determine the cumulative absorbed dose for single inclusions in sliced brick samples is explored in this paper. The OSL scanner was configured to provide optical stimulation using laser sources with either blue/green or near-IR wavelengths. A regenerative OSL procedure was successfully applied to determine the palaeodose for single grains of quartz in the surface of the ceramic slices ranging in diameter from to . The results obtained compare well with calculated values of palaeodose obtained by scaling the measured values of palaeodose obtained using a single aliquot regenerative procedure with disaggregated quartz inclusions extracted from the same brick and prepared using the conventional inclusion technique. [Copyright &y& Elsevier]

Luminescence of a CaWO4 scintillator was studied in the temperature range 77–500 K using intense laser excitation in the 450–600 nm spectral region. Characteristics of the observed blue emission are similar to those of the intrinsic luminescence of calcium tungstate. The emission is concluded to be caused by cascade excitation of CaWO4 that results in a two-photon excited (TPE) luminescence. The features of TPE luminescence of CaWO4 are analysed in comparison to those obtained with UV and X-ray excitation. [Copyright &y& Elsevier]

The potential of cementitious building materials for use in retrospective dosimetry has been investigated by examination of three types of Portland cement, fine grain polymineral samples extracted from concrete and quartz inclusions extracted from ‘ready-mix’ mortar and samples of mortar applied to the external walls of buildings. The results of X-ray and optically stimulated luminescence measurements with samples of hydrated cement suggest that the emission associated with its presence in mortar, render and concrete is likely to be too weak for absorbed dose determinations of less than a few Gy. Measurements of the TL signal from quartz grains extracted from mortars indicate that a TL peak located at ∼170°C (5° s−1) and measured with coarse grains of diameter >350 μm provide the most promising approach for dose assessments above 100 mGy. [Copyright &y& Elsevier]

Spatially-resolved measurements of optically stimulated luminescence (OSL) were performed using a two-dimensional scanning system designed for use with planar samples. The scanning system employs a focused laser beam to stimulate a selected area of the sample, which is moved under the beam by a motorised stage. Exposure of the sample is controlled by an electronic shutter. Mapping of the distribution of OSL using a continuous wave laser source was obtained with sub-millimeter resolution for samples of sliced brick, synthetic single crystal quartz, concrete and dental ceramic. These revealed sporadic emission in the case of brick or concrete and significant spatial variation of emission for quartz and dental ceramic slices. Determinations of absorbed dose were performed for quartz grains within a slice of modern brick. Reconfiguration of the scanner with a pulsed laser source enabled quartz and feldspathic minerals within a ceramic sample to be differentiated using a single stimulation wavelength by measuring the time-resolved luminescence spectrum. [Copyright &y& Elsevier]

The feasibility of applying optically stimulated luminescence (OSL) techniques to obtain estimates of the burial age of lithic clasts in the form of pebbles of quartzose lithology is investigated in this study. We applied OSL measurement procedures to vein-quartz and quartzite pebbles from contexts at five sites with fluvial and coastal beach contexts of depositional age ranging from 500 ka to the mid Holocene. As in previous OSL studies with lithics, measured depth-dose profiles were interpreted to identify regions associated with key stages in the burial history of the pebbles, including the extent of pre-burial optical resetting, primary burial and any subsequent secondary stages of exposure to sunlight. While some of the pebbles had not been fully optically reset before burial, none were in field saturation, as commonly encountered with larger lithic clasts such as cobbles. The relatively low concentrations of radionuclides within vein-quartz and quartzite pebbles simplified the assessment of the radiation dose rate. OSL age estimates consistent with independent dating evidence were obtained for the three sites sampled in the UK (Langford Quarry, Leet Hill Quarry, Swanscombe Skull Site and Barnfield Pit) and one of two sites tested in Portugal (Forte Cão), whereas evidence of secondary optical bleaching detected in pebbles from a second site (Vale de Atela) underestimated the independent age for primary burial. The oldest depositional age of the contexts tested was ~500 ka (Leet Hill Quarry), and for some of the pebbles tested there was the capacity to extend the potential dating range further as the age equivalence of the limiting value of D e was in excess of 1 Ma. The advantages of working with smaller, portable, clasts in the form of pebbles and with a lithology of higher transparency opens up a wide range of potential applications, whether the depositional processes are environmental or anthropogenic in origin or modification. • New approach to the dating of Quaternary sediments containing vein-quartz and quartzite pebbles. • OSL techniques applied to sliced pebble cores produce depth-dose profiles that are related to optical exposure history. • Successful comparison of OSL ages with independently dated MIS 12, MIS 11, MIS 5 and Holocene depositional contexts. • Low dose rates for vein-quartz and quartzite pebbles potentially enable further extension of the dating range. [ABSTRACT FROM AUTHOR]

Abstract: Three methods of individual dose reconstruction, namely dose calculations based on the available archive data and on the individual questioning of inhabitants, EPR dosimetry in human tooth enamel, and retrospective luminescence dosimetry (RLD) with quartz inclusions in the bricks were applied for assessment of accumulated external doses in Dolon village (Kazakhstan), which is one of the most affected settlements as a result of 29.08.1949 nuclear test at Semipalatinsk nuclear test site. Dose values obtained by EPR and RLD methods were compared with computed dose values. The available data on soil contamination with 137Cs and in the vicinity and inside Dolon village were used for interpretation of the results of comparison. Based on a calculated value of 2260mGy for the dose in the air along the central axis of the trace located NW of Dolon, the doses in the air over whole village and for the south-eastern part of the village containing the RLD sampling points were estimated as and , respectively, the latter correlates well with the RLD dose value of . The “upper level” of the mean “shielding and behavior” factor of dose reduction for inhabitants of Dolon village was estimated as ; this was performed by comparing the individual EPR tooth enamel doses with the calculated mean dose for the settlement. The individual dose estimates by EPR dosimetry were compared with individual dose values obtained by modeling. Uncertainties of the calculated individual doses were evaluated using Monte Carlo simulations. The individual dose estimates by EPR method are lower in comparison with mean computed doses and with RLD data, but they are in a good consistency with computed individual dose values in Dolon village based on the results of individual questioning with account of individual “shielding and behavior” factors. [Copyright &y& Elsevier]