Search

It is required to achieve an accurate measurement of 10 B distributions and concentrations in the tumor cells for boron neutron capture therapy (BNCT). We employed a technique of neutron capture autoradiography (NCAR) of the whole body samples of tumor bearing mice using CR-39 plastic track detectors to the measurements of 10 B accumulations in mice. In order to confirm the validity of the NCAR measurements, the differential REL spectrum for the neutron-induced particles emitted from the standard filter paper sheets was compared with that for 10 B-compound solution. Differential REL spectrum for protons originated from the biogenically abundant nuclides through 14 N (n, p) 14 C and 1 H (n, n′) 1 H reactions was measured in vivo using a small piece of CR-39 inserted into the tumor of mouse.

During the manufacturing process in the cement industry, raw materials of different levels of natural radioactivity are utilized. In this study we present the radiological impact of cements as a building material and the different raw materials used in their manufacture. A total of 218 samples of raw materials and their end product cements were collected from the cement industry of Macedonia (The Former Yugoslav Republic) during the period 2005–2007. The specific activities, evaluated by gamma spectrometry analysis, showed the highest mean specific activity in fly ash ( 226 Ra, 107 ± 45 Bq kg −1 ; 232 Th, 109 ± 30 Bq kg −1 ; 40 K, 685 ± 171 Bq kg −1 ), which is used as a raw material. However, the final cement product usually has relatively lower activity compared with the activity of the raw material and the mean specific activity of the final cement products were lower ( 226 Ra, 42 ± 10 Bq kg −1 ; 232 Th, 28 ± 6 Bq kg −1 ; 40 K, 264 ± 50 Bq kg −1 ). The radium equivalent activity and the hazard index were calculated for each sample to assess the radiation hazard. The mean annual effective dose originating from the cements was found to be 111 ± 22 μSv y −1 , which is below the recommended EC limit of 300 μSv y −1 .

Activated charcoal was widely used in radon researches and mitigation applications because of good adsorption ability. In the paper, a simple model that can predict radon removal efficiency (η) for radon mitigation applications using flow-through activated charcoal system was developed based on the previous works. Experiments were conducted with a flow-through activated charcoal system to validate the model and study the influence of factors on η. The experimental results of η are consistent with the theory to within 4% at the flow rates of 1–3 L/min, but range from 2% to 14% at the flow rates of 4–5 L/min. The equilibrium time of radon linearly decreases with rising flow rate, and η decreases with rising flow rate. With moisture competing with radon for adsorption sites on the activated charcoal, radon reaches the equilibrium concentration more quickly than moisture does. As relative humidity increases, η decreases, but the radon equilibrium concentration increases. The values of η are bigger for those smaller particle sizes with the same type of activated charcoal. The results of this paper are useful for designing activated charcoal systems at indoor environmental conditions and predicting η for radon mitigation applications.

Timepix-based detectors have been deployed in a variety of mixed-field situations for dosimetry applications, such as Radon monitoring, evaluating propagating hadron therapy beams, and assessing radiation doses received by airline passengers and crewmembers. However, one of the most significant and complex achievements of Timepix-based detectors is their success in evaluating the incident charged particle fields in space radiation environments, both inside spacecraft and exposed to space with minimal shielding. This paper documents the applications of Timepix-based instruments for the purpose of determining the radiation doses experienced by astronauts. The incident neutron and to a much lesser extent, the dosimetric relevant photon component of that radiation field are not addressed in this review article. Timepix-based detectors have been deployed in a variety of mixed-field situations for dosimetry applications, such as Radon monitoring, evaluating propagating hadron therapy beams, and assessing radiation doses received by airline passengers and crewmembers. However, one of the most significant and complex achievements of Timepix-based detectors is their success in evaluating the incident charged particle fields in space radiation environments, both inside spacecraft and exposed to space with minimal shielding. This paper documents the applications of Timepix-based instruments for the purpose of determining the radiation doses experienced by astronauts. The incident neutron and to a much lesser extent, the dosimetric relevant photon component of that radiation field is addressed separately in this volume.

The shape of infrared stimulated luminescence signals (IRSL) from feldspars has been the subject of numerous studies in the field of luminescence dating. Specifically linearly modulated IRSL signals (LM-IRSL) are commonly assumed to consist of several first order components corresponding to distinct optical stimulation cross sections. This paper models the shape of LM-IRSL signals using a recently proposed kinetic model, which describes localized electronic recombination in donor–acceptor pairs of luminescent materials. Within this model, recombination is assumed to take place via the excited state of the donor, and nearest-neighbor recombinations take place within a random distribution of centers. The model has been used previously successfully to describe both thermally and optically stimulated luminescence (TL, OSL). This paper shows that it is possible to obtain approximate solutions for the distribution of donors in the ground state as a function of two variables, time and the distance between donors and acceptors. Approximate expressions are derived for several possible modes of optical and thermal stimulation, namely TL, OSL, linearly modulated OSL (LM-OSL), LM-IRSL and isothermal TL (ITL). Numerical integration of these expressions over the distance variable yields the distribution of remaining donors at any time t during these experimental situations. Examples are given for the derived distributions of donors in each experimental case, and similarities and differences are pointed out. The paper also demonstrates how LM-IRSL signals in feldspars can be analyzed using the model, and what physical information can be extracted from such experimental data. The equations developed in this paper are tested by fitting successfully a series of experimental LM-IRSL data for Na- and K-feldspar samples available in the literature. Finally, it is shown that the equations derived in this paper are a direct generalization of an equation previously derived for the case of ground state tunneling.

A novel ion detection method has been developed and studied in this paper for the first time to detect and observe tracks of nitrogen ions and their angular distribution by unaided eyes in the Amirkabir 4 kJ plasma focus device (PFD). The method is based on electrochemical etching (ECE) of nitrogen ion tracks in 1 mm thick large area polycarbonate (PC) detectors. The ECE method employed a specially designed and constructed large area ECE chamber by applying a 50 Hz–high voltage (HV) generator under optimized ECE conditions. The nitrogen ion tracks and angular distribution were efficiently (constructed for this study) amplified to a point observable by the unaided eyes. The beam profile and angular distribution of nitrogen ion tracks in the central axes of the beam and two- and three-dimensional iso-ion track density distributions showing micro-beam spots were determined. The distribution of ion track density along the central axes versus angular position shows double humps around a dip at the 0° angular positions. The method introduced in this paper proved to be quite efficient for ion beam profile and characteristic studies in PFDs with potential for ion detection studies and other relevant dosimetry applications.

This paper presents a way to determine the angular and spatial distributions of the thermal neutron source strength of a boron neutron capture therapy (BNCT) beam. The experiments applied 1) the indirect neutron radiography, 2) the cadmium difference method, and 3) the instrumental neutron activation analysis. The measured data were processed by the spectrum deconvolution technique to resolve into a proper set of angular and spatial distributions. This paper took the epithermal neutron beam of the BNCT facility at the Tsing Hua Open-pool Reactor as an example.

Radon concentration in indoor air has been measured in many countries in a large number of buildings – mainly in houses but also in apartments and workplaces – mostly as a result of the application of radon policies and regulation requirements. However, few systematic analyses are available on radon concentration variations within buildings and between close buildings, especially as regards workplaces; such variations can have a significant impact on indoor radon exposure evaluation, and ultimately on the assessment of the dose from radon received by workers. Therefore, a project was started in 2006 aimed to study the spatial variation of radon concentration among and within about 40 buildings of the Istituto Superiore di Sanita (ISS), a research institute of public health located in Rome over a small area of less than 1 km 2 . Nuclear track detectors (CR-39) were used to measure radon concentration for two consecutive six-month periods, in more than 700 rooms of the surveyed buildings. The paper describes the project in detail and preliminary results regarding 558 rooms in 29 buildings. Coefficient of variation (CV) was calculated as a measure of relative variation of radon concentration between buildings, between floors, and between rooms on the same floor. The CV between buildings resulted quite high (88%), a lower CV (42%) was found for variation between floors, whereas room-to-room CV on the same floor ranged from 25% at first floor level to 48% at basement level. Floor mean ratios, with ground floor as the reference level, were calculated for each building in order to study the correlation between radon concentration and floor levels. Although no clear trend was observed, the average basement/ground floor ratio of radon concentrations resulted about 2.0, whereas the average sixth floor/ground floor ratio of radon concentrations was 0.5. Some discussion on the potential impact of the results of this study on policies and radon regulations are also included in the paper.

Albedo dosemeters, usually based on thermo-luminescence detectors, have been frequently employed in personal neutron dosimetry. Their main advantages are the high sensitivity and the reduced angular dependence, whilst the disadvantages are the sensitivity to photons and the significant energy dependence of the response, which drops dramatically above 0.1 MeV. The present paper proposes an albedo dosemeter based on a planar PADC coupled with a 10 B converter. This dosemeter shows good potentials in terms of photon insensitivity, limited angular dependence and high neutron sensitivity. Its use coupled with a dosemeter sensitive in the MeV region, should result in promising dosimetric performances. The response of the PADC based albedo dosemeter was characterized through irradiations in reference neutron fields of 241 Am-Be, 252 Cf and 252 Cf(D 2 O) and Monte Carlo simulations with the code MCNP-4C. The paper presents the results of the experimental and computational studies and outlines the relevant dosimetric performance of the new albedo dosemeter.

The formalism of the many-hit model (MHM) [Fromm, M., Awad, E.M., Ditlov, V.A., 2004. Many-hit model calculation for track etch rate in CR-39 SSNTD using confocal microscope data. Nucl. Instr. Phys. Res. B 26, 565-575; Ditlov, V.A., Awad, E.M., Fromm, M., Hermsdorf, D., 2005. The Bragg-peak studies in CR-39 SSNTD on the basis of many-hit model for track etch rates. Radiat. Meas. 40, 249-254] is applied in order to describe the bulk etching rate V B of non-irradiated polymer detectors. In such a case the etching process should be easier to understand in terms of interactions of physical and chemical processes superimposing material diffusion and reaction kinetics. In a paper [Ditlov, V.A., 2005. Formation model of bulk etching rate for polymer detectors. Radiat. Meas. 40, 240-248] first attempts have been made to develop formulae for the calculation of V B dependence on the concentration C and temperature T of the etchant solution. Therein, it is shown that V B have to be studied in a broad range of C and T including very low and very high values. The formulae of the MHM contain some free adjustable parameters of definite physical meaning, which have to be determined by fitting the experimental data. In the present paper data for V B of LR-115 cellulose nitrate detectors have been analysed to decide on the reliability of the modelling of etching processes and to determine possible physical-based parameters.

Natural diamond based ionisation chambers commercialised by PTW are used in several hospitals, and their dosimetric properties have been reported in many papers. Nevertheless their high costs and long delivery times are strong drawbacks. Advancements in the growth of synthetic diamonds offer new possibilities. This paper presents the dosimetric analysis in terms of stability and repeatability of the signal, background signal, detector response dynamics, linearity of the signal with the absorbed dose and dose rate dependence of synthetic optimised polycrystalline and single crystal diamonds. Both were elaborated at the CEA-LIST using the chemical vapour deposition (CVD) growth technique. The first dosimetric evaluation of single crystal diamond detector, reported here, shows a repeatability better than 0.1%, a good sensitivity around 70 nC/Gy compared to 3 nC/Gy for optimised polycrystalline diamond, very fast response with rise time around 1 s. Moreover, the signal linearity vs absorbed dose and energy dependence are very satisfactory. This preliminary dosimetric study with medical linear accelerators proves that diamond, and more precisely synthetic single crystal diamond, appears as a good alternative to air ionisation chambers for quality beam control and could be a good candidate for intensity modulated radiation therapy (IMRT) beams dosimetry.

Strong fields of thermal and epithermal neutrons as used for Boron Neutron Capture Therapy (BNCT) show a relatively small gamma dose. However, for accurate dose estimation, both the neutron as well as the gamma component has to be considered. Different approaches have been studied with various thermoluminescence detectors (TLDs). As a result, CaF2:Tm detectors (TLD-300) are attributed to be most insensitive to thermal neutrons but not tissue-equivalent. In this paper we focus on the measurement of the gamma dose with TLD-300 in mixed irradiation fields. To overcome the disadvantage of being not tissue-equivalent, a study on energy compensation filters was performed. The paper comprises also calibrations of TLD-300 using energy compensation filters at the PTB-reference field for thermal neutrons, and first test experiments at the TRIGA Mainz including simulations.

After the nuclear reactor accident in Chernobyl in 1986, most countries of the European Union (EU) established monitoring networks measuring outdoor γ -dose rates for early warning. The data are composite values γ -dose rate due to terrestrial, cosmic and artificial radiation sources, and in most cases also include some instrument background. While EURDEP is mainly designed for exchanging and stocking data during radiological emergencies, the data it is storing in its database may potentially contain valuable information about spatio-temporal variations of the Rn 222 source term which can be used for the validation of atmospheric transport models and other atmospheric tracer applications. The use of γ -dose rates as a proxy for outdoor radon concentrations is indeed possible if one can extract the terrestrial γ -dose rate contribution from the values reported in EURDEP. It is the purpose of this paper to discuss the preparation of the terrestrial γ -dose rates using EURDEP data and to present seasonal maps of terrestrial γ -dose rates in Europe. Such maps could be used for the preparation of Rn 222 source term which can be used for the validation of atmospheric transport models as well as for exploring variations in soil moisture content, an important parameter in flood prediction. These applications are the focus of the ongoing studies, but beyond the scope of this paper. In this paper, we show how the terrestrial γ -dose rate can be derived from the emergency monitoring data and two seasonal maps of γ -dose rates at the European scale are produced using geostatistics.

A new grab sampling method for the simultaneous determination of radon progeny and thoron progeny in air has been developed and demonstrated by the first author of this paper a few years ago. The characteristics and capabilities of this method are discussed in the present paper in detail. The method is based on gross beta counting of filtered aerosol samples counted over successive time intervals using an end-window Geiger–Muller counter. The measured counting rate versus time curve is analyzed by fitting to it some linear combination of the theoretical decay curves of the decay products with the knowledge of the counting efficiencies and some other quantities. Defined solid angle absolute beta counting was used to evaluate the counting efficiencies for the decay products one by one. So, the method is an absolute one that does not demand further calibration. The decay products of radon and thoron can be determined separately and simultaneously. The systematic error of the results, deriving from the inaccurate evaluation of the counting efficiencies, is probably lower and can be estimated more surely than that of the methods based on alpha counting. The method is highly sensitive: accurate results can be obtained for 214Pb, 214Bi, 212Pb, EEDC 222 and EEDC 220 even outdoors. However, the results for 218Po and 212Bi are much more inaccurate and 208Tl cannot be determined at all. The reliability of the determinations can be raised significantly using conditional computations based on the information obtainable from some theoretical considerations and models. The method can be used in a broad activity concentration range, equally in caves, mines, houses or outdoors. The above characteristics and capabilities of the method are demonstrated in this paper through the detailed presentation and analysis of the results obtained for three samplings performed indoors in a house, in a cave, and outdoors, respectively. The known advantages and drawbacks of the method are also surveyed in detail.

This paper describes the sample preparation studies carried out to determine gross alpha activities in waste materials by means of alpha-particle track counting using CR-39 detector. Sample preparation for the track registration technique using evaporation or electroplating methods (also known as conventional “dry methods”) has a number of drawbacks. The distribution of tracks in different areas of the detector surface is non-uniform, so accurate quantitative determinations depend on tedious and time-consuming counting of tracks under an optical microscope. In this paper, we propose the use of tensioactives in sample preparation to achieve uniform track distribution over the entire detector surface, which enables track density to be evaluated by scanning a small representative area. Under our counting conditions, uniform distribution was achieved with 0.2 ml of Teg from a planchetted source. Furthermore, track registration techniques using solution media (also known as the “wet methods”) and conventional “dry methods” were analysed and compared with the proposed method. The reproducibility of the procedure described in the study was tested by analysing gross alpha activity in two low-level nuclear waste samples at two different laboratories.

Parametric investigations were carried out on electrochemical etching (ECE) process of Lexan polycarbonate (PC) detector. Outstanding experimental results showing the enlargement of the registration energy range of α -particle tracks of the PC and decrease of ECE time are presented in this paper. In the experiment, major parameters such as etching solution and ECE conditions are focused. Ethylene diamine is applied as an additional chemical agent to increase the bulk etching rate ( V B ) which is maintained below a critical value ( 20 μ m / h ) . By using mixture of KOH, CH 3 OH (methanol), NH 2 ( CH 2 ) 2 NH 2 (ethylene diamine) and H 2 O and applying interval-based ECE process in total duration of 70 min, expanded α -registration range of 0.5–4.7 MeV have been achieved, as well alpha track diameters decrease with increasing of alpha particle energy. In this process the density of background tracks also decreases comparably. In this paper, electric current is introduced as an effective ECE parameter for improving detection efficiency of low α -particles energy in the PC.

The paper concerns applications of LR-115A, CR-39 and PM-355 solid-state nuclear-track detectors (SSNTDs) for investigation of pulsed fluxes of protons below 300 keV. The proton streams were generated by the RPI-IBIS device operated with hydrogen puffing [Baranowski et al. 2000. Studies of hydrogen discharges in RPI-type devices with different electrode configurations. Czech. J. Phys. 50 (Suppl. S3), 101–107]. To perform ion mass- and energy-analysis, a Thomson mass-spectrometer equipped with a special input system and exchangeable detectors was used. A quantitative analysis of proton tracks upon Thomson parabolas was performed by means of an optical microscope equipped with a CCD camera. It made possible to measure proton tracks and to determine their statistics. The paper presents proton energy spectra recorded with the selected detectors, and responses of these detectors to protons of energy from about 30 to 300 keV. The results are important for verification of detector characteristics and for measurements of protons at different experimental conditions.

A representative National Survey to evaluate the exposure to natural sources of ionizing radiation in dwellings was conducted in all the 21 Italian Regions from 1989 to 1998, and the complete results are reported in this paper. Radon concentration was measured for two consecutive 6-month periods (generally covering the spring–summer and autumn–winter seasons) in one room, usually the main bedroom, of each surveyed dwelling. Validated radon concentration measurements were obtained for a total of 5631 dwellings, distributed in 232 towns (all the 50 towns with more than 100,000 inhabitants and 182 randomly sampled smaller towns). The national average, weighted by the population of each Region, of the annual radon concentration is 70 Bq m - 3 , the geometric mean is 52 Bq m - 3 , and the geometric standard deviation is 2.1. The fraction of dwellings with a radon concentration exceeding the reference levels of 150, 200, 400, and 600 Bq m - 3 are 7.7%, 4.1%, 0.9%, and 0.2%, respectively. Regional averages ranged from about 25 Bq m - 3 to about 120 Bq m - 3 . The uncertainty of regional values can be relevant in the case of small Regions, where few small towns were sampled, however such uncertainties do not affect national values significantly. A log-normal model underestimates the fraction of dwellings with high radon concentration and needs to be adjusted to obtain a better fitting. Two complete 6-month measurements were obtained for 4742 dwellings. The regional values of the geometric mean and of the geometric standard deviation of the winter/summer ratio ranged from 0.81 to 2.58 and from 1.32 to 1.88, respectively. The corresponding national values were 1.23 and 1.71, respectively. These results and their implications are discussed in the paper.

Passive technique based on a diffusion chamber fitted with permeable membrane and CR-39 detector is applied in the present study. The detector response and the filter permeability for radon were measured as a function of exposure temperature. The combined effects on the detector and membrane are studied in the temperature range from 27 to 58 °C. Two membrane categories, the paper-type and the polymer-type, are used. The obtained results show advantages of paper-type membranes over polymer-type, where the permeability of paper filter is temperature independent. As a result, the detector response is increased with temperature by a higher rate in case of polymer membrane. Consequently, the using polymer type in radon measurement at unusual temperature needs corrections. The measurements were taking into consideration the effect of temperature on the radon source emanation power which increased from 0.518 to 0.724 in the studied temperature range. The combined uncertainty for all measured parameters is calculated and discussed.

The classic paper of Mejdahl (1979) on beta doses to quartz grains has been a standard reference for many years. In this paper we present an update of the data for beta doses to spherical quartz grains from internal and external natural sources, using dose point kernels based on modern spectra and Monte Carlo calculations. The differences from the Mejdahl results are not large, reflecting the modest adjustments in nuclear data and in the physics of electron–photon cascades in recent decades. It is recommended that, for a grain of original diameter 100 μm which has had a 9 μm layer etched away, the typical attenuation factor should be approximately 0.92 rather than the traditional 0.90. In addition, theory and data for the effects of etching on the average beta dose are presented, and we outline procedures for the estimation of beta doses for any situation that can be modelled using a series of concentric uniform shells.

Solid State Nuclear Track Detectors (SSNTDs) have been used for corpuscular diagnostic in numerous high-temperature plasma experiments. This paper presents different applications of the detectors mentioned above, particularly in nuclear fusion investigations. Some new projects and proposals of the use of such detectors in large-scale plasma experiments, e.g. tokamaks, and laser-fusion facilities are demonstrated. To use the SSNTDs in the optimal way and to determine their detection characteristics, detailed calibration studies of the selected plastic detectors (CR-39, PM-355, PM-500, PM-600) have been performed at IPJ for several years. To carry out calibration measurements of these detectors, ion beams from different accelerators were applied. The paper presents detection characteristics, i.e. track dimensions as a function of ion energy, atomic number and etching time.

The paper presents the results of a study of radiation energy storage, radiation effects, and radiation induced changes of optical properties in crystals KH2PO4 (KDP), (NH4)H2PO4 (ADP), and crystals KDP doped with either deuterium (KDP : D) or Cr (KDP : Cr). Both the X-rays and H + (0.71 MeV ), He + (4.6 and 27 MeV ), N + (16 MeV ) ion beams were used for irradiation of the crystals studied. Optical absorption spectra of KDP were measured after irradiation with various H+ ion beam doses, and accumulation of the radiation-induced defects was estimated. Considerations of the radiation effects in these crystals under irradiation with the ion beams were made taking into account the results of Monte Carlo simulations using the TRIM computer codes. Using the experimental and theoretical results the paper discusses the similarities and differences of these crystals with respect to radiation hardness and the processes of radiation energy storage.

In a former paper ( Fain et al., 1994 ), a general TL model based on deep-trap competition was proposed, but only a preliminary qualitative approach was made for the heating stage. The purpose of the present paper is to present more accurate calculations and their comparison with experimental data. For the sake of simplicity, only the one TL-trap model is considered here. During heating, the following occurrences are taken into consideration after the thermal release of one electron: (i) retrapping on a TL-trap; (ii) capture in a deep trap; (iii) recombination with a spatially correlated hole; (iv) recombination with a non correlated hole centre. Using the “quasi-equilibrium approximation”, a set of two differential equations governing the kinetics is proposed. Their integration allows for the prediction of the shapes of glow curves and growth curves. Satisfying fits were obtained with a large range of experimental results.

The paper describes thermoluminescence (TL) properties of AlN:Y 2 O 3 ceramics irradiated with ionising radiation. A high TL sensitivity of AlN:Y 2 O 3 ceramics to radiation encouraged a study of the AlN ceramics for application as a dosimetric material. The paper presents experimental data on: glow curve, emission spectrum, dose response, energy dependence, influence of heating rate and fading rate. The measured TL characteristics were compared with those of well-known, widely used TLDs, i.e. LiF:Mg,Ti, LiF:Mg,Cu,P and Al 2 O 3 :C. It is concluded that AlN:Y 2 O 3 ceramics showing a radiation sensitivity which is approximately 50 times greater than that of LiF:Mg,Ti is an interesting dosimetry material; however due to a high fading rate of the TL of AlN:Y 2 O 3 on storage at room temperature, a further development of the material for improving the fading characteristics is needed for its application for dosimetry purposes.

The present paper reports on the first results of a comprehensive thermoluminescence (TL) investigation of a commercially available X-ray phosphor, Sr 3 (PO 4 ) 2 :Eu 2+ . Its TL emission spectrum is dominated by a single emission band centered at 420 nm, which is characteristic of Eu 2+ . The glow curve has two distinct peaks at 100 and 260°C respectively (measured at a heating rate of 1°C/s). There is a much weaker emission around 570 nm, which is localised in a completely different single glow peak around 140°C. Based on the glow curve characteristics discussed in the paper, Sr 3 (PO 4 ) 2 :Eu 2+ seems to be not only a promising TL dosimeter material, but it is an interesting model system for studying thermoluminescence kinetics.

This paper presents a model that describes the radiation response of a polycrystalline material with different trap populations in the bulk material and on the crystalline surface. The model describes the free charge created by the impact of a high-energy particle as a pseudo-classical ideal gas, which spreads through the crystal according to a diffusion equation. The charges can recombine, be trapped in a bulk trap or be trapped on a crystal surface. The paper describes the assumptions behind the model, the differential equations they lead to and a numerical finite-differences method by which the equations can be solved. The model parameters and their correlation to real world parameters are discussed and possible refinements are discussed. The typical properties of the model and the scope of theoretical calculations that can be performed with it are demonstrated on a number of examples with a set of idealized parameters. In particular, the model shows a dependency of the linear radiation sensitivity on the energy of the incoming radiation particles. The model is applied to the simulation of growth curves, where saturation and superlinearity can be observed. The model has useful applications in the fields of electron spin resonance (ESR) dating and of luminescence dating.

Electron paramagnetic resonance (EPR) spectroscopy, as usually practiced, involves sweeping the magnetic field and not the frequency. In the first place this means that EPR spectra are not unique and will depend, in many cases, on the microwave frequency used. This paper focuses on what is measured and how well we understand what it is that is being measured. The paper outlines the principles that should be followed in setting up EPR spectrometers for quantitative intensity measurements, critical for dosimetry and dating, including adjustments to the microwave bridge, choice of microwave power, temperature stability and reproducibility.

This paper describes the results of measurements on the traces of uranium found in 24 water samples collected from various sources in four important cities of Uttar Pradesh (India). The sources of water samples were municipal taps, private hand pumps, jet pumps and natural rivers, etc. Melinex-O plastic sheets of thickness ≌ 100 microns were used as detectors for the registration of fission tracks produced in the 235 U (n,f) reactions. In the case of treated drinking water samples collected from taps supplied by the water works departments of various cities (basic sources for these samples being tube-wells, dams and rivers in different cities as specifically indicated in the paper), the values of uranium concentrations were found to lie between 0.87 ± 0.01 and 11.36 ± 0.34 μ g/l. For the untreated water samples collected from private jet pumps and hand pumps, the U-contents were found to vary from 2.02 ± 0.03 to 9.07 ± 0.10 μ g/l. The levels of uranium concentration in untreated river water samples of various cities collected directly from the river streams were found to range from 0.92 ± 0.01 to 5.37 ± 0.06 μ g/l. The average uranium intake resulting from the drinking tap waters in these cities has also been calculated. They are found to be much less than the maximum permissible limit of 40 mg/day in every case reported in this paper.

The pit produced by etching the track left by a heavy ion in CR-39(DOP) for a fixed length of time and with an etchant of known concentration and temperature has two principal length scales—the diameter D of the open end of the pit and the depth d of the pit. These two parameters allow the determination of the charge Z, and the energy/nucleon e, of the heavy ion. In the first part of this paper we present the results of an experiment, involving the scattering of 12C from various targets, performed at the Pelletron at TIFR, Bombay. The experimental data on d and D of the above ion, obtained after etching the SSNTD for 3 hours at 70°C in a standard manner, are then compared in the second part of the paper with theoretical estimates based on some established formulae. We present parametrizations of the diameter D and the depth d in terms of Z and e on the basis of the said formulae. Our method has the following advantages: (i) there is no track recognition problem (which arises when repeated etching of a track is required); and (ii) there is no uncertainty regarding the total time of etching, which is a problem for identification methods requiring a knowledge of the range of the particle.

In this paper, we examine several models for the description of TL, focusing most attention on the properties of optical bleaching, in an effort to determine if realistic models can be devised which accurately describe the observed behavior. The models considered include multiple trapping and recombination levels, radiative and non-radiative processes, trap interaction effects, retrapping of released charge, and include transitions into and out of the recombination centers as well as the traps. All such phenomena are likely to occur in real materials and should be included in any model purports to describe such materials. This paper concludes that models which account for the recombination of feed electrons with trapped holes during the bleaching period appear to be the most successful at describing the observed phenomena.

Rare Earth doped-phosphate glasses have received a great deal of attention on research because of their applications in biomaterial engineering, however, little to no attention has been given to potential luminescent properties from “heating” these materials when exposed to ionizing radiation. This paper aims to presents results on investigations of Thermoluminescent (TL) and Optically Stimulated Luminescence (OSL) properties of the Er3+-doped phosphate glasses produced at the Physics Department of Federal University of Juiz de Fora on a characterization for beta radiation dosimetry. It was used a RISO TL/OSL reader and its coupled 90Sr/90Y beta source. The experimental findings indicate that the material presents linear responses of thermo (TL) and optically stimulated luminescence (OSL) over the absorbed dose range of 2 to 20Gy. Its emitted TL and OSL signal is more intense and with extended linearity range compared with undoped phosphate glass, probably caused by two absorption bands on 350–380 nm from Er3+. Further investigations are being carried out on its applications to other types and qualities of radiation.

In a reprocessing facility, it is required to develop a detector which can monitor plutonium (Pu) amount in the Pu solution containing the Fission Product (FP) in order to strengthen the safeguards capability. In order to investigate gamma rays which is applicable for Pu monitoring for High Active Liquid Waste (HALW), Ce:GAGG (Ce:Gd 3 Al 2 Ga 3 O 12 ) scintillator which can measure a wide range of energy at high radiation dose rate and has relatively high resolution was newly designed and developed in deal with aim for monitoring of Pu quantity. Gamma ray measurement was conducted to HALW in the concrete cell by the designed detector, and it was confirmed that Eu-154 was detected using GAGG scintillator in HALW. In this paper, detector design, results of gamma ray spectra measurement, applicability evaluation to Pu monitoring and the future plan are presented.

This paper reports breakthroughs on 4π panorama ion emission mechanisms understanding in a plasma focus device (PFD) in particular hydrogen ion (proton) images detected for the first time in panorama mega-size polycarbonate ion image detectors (MS-PCIDs). The MS-PCIDs were processed in novel panorama single-cell mega-size electrochemical etching (MS-ECE) image detection systems by 50 Hz - HV method. A circular and a rectangular MS-PCIDs form a “mega-size cylindrical ion detector” capable to efficiently detect 4π proton emission with “Proton Cathode Shadow” or any other phenomena on ionographs or images, observable by the unaided eyes with potential for relative “dynamic proton spectrometry”. The effects of 6 circular MC-PCID distances from a flat-end cone anode top, anode top geometry, and type of gas on ion emissions in particular protons are presented and discussed. The potential of near 4π availability of PFD space highly enhances efficient PFD applications, what has been limited by narrow beam emission exercises within small solid angle on or around z-axis.

This paper presents experimental and theoretical determination of CR-39 and Makrofol calibration coefficients in diffusion chambers for radon measurements. Experimental calibration was performed by irradiation of detectors in a calibration chamber; radon concentration in the chamber was continuosly measured by RAD7 device. Calculations were performed by the previously developed software for CR-39 detector. In addition the software was modified to enable calculation for Makrofol by implementing V function and other relevant data for this kind of detector. A good agreement was found between experimental and theoretical approaches. The comparison enabled selecting V function for CR-39 that gave the best agreement with the experimental results. Optimisation of chamber and detector dimensions was theoretically performed for different etching times. The dependence of calibration coefficient on 218Po deposition fraction was also analysed.

For the detection of plutonium particles released from the Fukushima Daiichi nuclear power plant, we developed a high-resolution alpha-particle imaging system. The detector of the alpha-particle imaging system consists of a thin ZnS(Ag) sheet, a light guide, and a high quantum efficiency 1-inch square position-sensitive photomultiplier tube (PSPMT). The ZnS(Ag) sheet was optically coupled to the PSPMT with a 1.5 mm thick light guide between them. The Anger principle was used for the position calculation of the alpha particles. The spatial resolution of the alpha-particle imaging detector was 0.45 mm full width at half maximum for 5.5 MeV alpha particles. The uniformity of the imaging detector in the central part of the field of view was ±7%. The detection efficiency was 76% for 5.5 MeV alpha particles. Although the background count rate was 8.1 counts per minute because of the collection and detection of alpha particles from radon daughters in the air, it could be decreased to 0.1 counts per minute if the detector surface was covered with paper. There was no increase in the background count rates of 137Cs gamma photons and 45Ca beta particles. We obtained high-resolution variable phantom images and particles of alpha emitters with the system. We conclude that the alpha-particle imaging system developed is promising for the detection of plutonium particles in samples collected near the Fukushima Daiichi nuclear power plant.

The lower operation limit of common tissue equivalent proportional counters (TEPCs) is about 0.3 μm in simulated site. On the other hand, the pattern of the particle interactions at the nanometric level, which has a correlation with the radiation induced damage on the DNA, is measurable by only three instruments worldwide. In order to fill this gap, a novel TEPC capable of simulating site sizes down to 25 nm was designed and constructed. Its response was characterized with gamma, neutron and carbon beams and the capability in measuring microdosimetric spectra at 25 nm was demonstrated. The present paper aims at describing a further characterization of this TEPC by simulating with the Monte Carlo FLUKA code the microdosimetric spectra measured with a carbon beam. Since the sensitive volume of the TEPC has an unconventional shape, a study on the chord length distribution for the adopted irradiation set-up was performed and compared with the analytical one. The results show a good agreement between the experimental data and the FLUKA simulations, showing that this code is capable of reproducing microdosimetric spectra of a carbon beam down to 25 nm in simulated site.

A method of determining high fluence rate for D-T neutron source by using two long counters is introduced. One long counter contains a BF3 proportional counter, and a response of 1.1 cm2 is determined by calibration. The other long counter contains a gamma compensated boron neutron ionization chamber, and a response of 2.06e-5 cm2 is determined by comparing with the results of long counter containing BF3 proportional counter. By appropriately arranging the two long counters, fluence measurements are performed at the high intensity D-T neutron generator (HINEG). The results of the experimental characterization to the long counter are presented at this paper.

The state-of-the-art in the electrochemical etching (ECE) amplification of charged particle tracks in polymeric detectors and its applications in particular in radiation dosimetry are presented and discussed in this paper. During the past quarter of century, extensive efforts have been made on research and development in the world as well as at NRPD in AEOI on production of high voltage generators, construction of ECE chamber systems, optimization of ECE conditions, development of detectors, studies on basic physical and chemical phenomena, promotion of large-scale applications, etc. Quality high voltage generators can now be home made or are commercially available. The ECE chamber systems are advanced for special purposes as well as for large-scale applications (e.g. pressure chamber, triplet ECE or TECE chamber, etc. from NRPD). Many parameters have been optimized and new parameters such as internal heating, pressure, detector dimensions, etchant volume, chamber insulation, etc. have been recently discovered. Lexan polycarbonates (PC) and CR-39 have been shown to be the most successful detectors for ECE, while other detectors were also applied. The fundamental phenomena including “dielectric breakdown”, “dielectric loss”, “electro-osmosis”, “dielectrophoresis”, “electrostriction”, etc. although primarily proved to exist and studied, need to be further studied. The novel triplet ECE (TECE) method has provided a new approach for track amplification, firing tree production, fractal tree generation, etc. Also the novel dyed ECE track (DYECET) method enables one to study in more detail the structure of tracks, cracks, fractals, etc. Large-scale radon monitoring indoors and outdoors, large-scale neutron personnel dosimetry, low level radionuclide determination in environmental samples, autoradiography, beam profile determination, etc. are considered some successful applications. In this paper, the above were explored with emphasis on recent discoveries and inventions at NRPD in AEOI.

Radon (Rn-222) is the heaviest noble radioactive gas which is created during the alpha decay of radium (Ra-226), the natural element present in the environment, mainly in rock and soil. Due to radon solubility, it may be found in drinking water, thus being an additional hazardous factor for the population. That is the major reason why it is important to be able to determine its concentration in water with reasonable accuracy and well known uncertainty. The aim of this paper is to thoroughly investigate the procedure of preparation of radon-in-water standards, which can be used in intercomparison measurements. The idea of the method is pumping radon gas of precisely determined activity through the well known water volume. The work focuses in particular on studying the influence of some factors on the procedure correctness, such as duration of relaxation time, the time of pumping radon from the source to chamber, the level of samples collection in water volume. The setup allowed acquisition of 10 ml water samples, radon concentration values obtained in them ranged from approximately 0.5 Bq/l to 12 Bq/l, with uncertainties of about 17% to 4–5%, respectively. The measured radon concentrations in water samples were generally lower than the calculated ones (systematic difference of about 13%), but the relation between these two quantities was linear in the whole range of measured values. It was also observed that there was no difference in results between the samples collected at different levels in the water volume. Furthermore, the optimal relaxation time was established. Therefore, the proposed method can be successfully used in radon-in-water intercomparison experiments.

The paper presents the dosimetric characterization of lithium calcium aluminum fluoride doped with europium and yttrium (LiCaAlF 6 :Eu,Y), synthesized by simple melt process. The characterization involved thermoluminescence (TL), optically stimulated luminescence (OSL), photoluminescence (PL) spectra, OSL emission spectra, minimum measurable dose, fading, dose response and photon energy dependence measurements. The OSL sensitivity of this phosphor to ionizing radiation was found to be ∼20 times to that of commercially available Al 2 O 3 :C, whereas, the TL sensitivity was ∼2.5 times to that of CaSO 4 :Dy (0.05 mol%). Photoluminescence (PL) and OSL emission spectra suggest that the Eu 2+ ions are responsible for OSL emission. The reusability of OSL discs for 50 cycles for a test dose of 20 mGy has been established. Minimum detectable dose for the phosphor in continuous wave OSL (CW-OSL) mode was found to be 0.5 μGy with negligible fading post 9 days of irradiation. Owing to its excellent dosimetric characteristics the phosphor is a highly sensitive dosimetric grade phosphor and is a serious contender for various radiological applications.

Halite (rock salt) is one of few materials, which have an ability to store information on absorbed dose of ionizing radiation. Previous studies of optically stimulated luminescence (OSL) response in sodium chloride indicated coexistence of fading, inverse fading and regeneration effect using newly developed variable delay optically stimulated luminescence technique (VD-OSL). This paper presents investigations of green OSL and IR OSL of dose response characteristics of halite mineral from Klodawa salt mine in Poland.

Advances in modeling during the past 20 years have contributed to better understanding of the luminescence properties of dosimetric materials. Three types of models have been used extensively in the literature: delocalized models based on transitions involving the conduction and valence bands, localized models usually involving different energy levels of the same trap, and semilocalized models which are based on a combination of localized and delocalized energy levels. The purpose of this paper is to provide an overview of recent developments in luminescence models, with an emphasis on the importance of delocalized transitions. Two recent theoretical developments are discussed, namely analytical equations based on the Lambert W-function which are applicable for delocalized models, and analytical equations based on tunneling in a random distribution of defects which are applicable for localized models. A new model for luminescence in quartz is proposed, which is applicable for time scales ranging from microseconds to seconds. Recent Monte Carlo simulations of ground state tunneling in a random distribution of traps and centers are discussed, which are based on a modified version of a previously published model. Some of the current challenges associated with luminescence signals measured at elevated temperatures are pointed out, and suggestions are made for future work in this research area.

In the present work, the microdosimetric one-hit detector model is evaluated by calculating the relative energy response of radiographic films. A small sample of typical radiographic films including the covering paper and the polyester base coated on by one emulsion layer is simulated by Geant4 toolkit. Silver bromide grains with the same cubical shape and dimensions of 1 μm randomly positioned in the emulsion are considered as the targets of the model. The relative energy response for eleven photon energies between 20 keV and 1.25 MeV is determined using the microdosimetric distributions of single energy deposition events in the grains. Calculations are performed for a few weight fractions of the silver bromide in the emulsion. The results show that for the weight fraction 13.3% of the silver bromide in the emulsion, calculated values of the relative energy response are in agreement with the experimental data within 20% difference. It can be concluded that the microdosimetric one-hit detector model satisfactorily predicts the energy response of radiographic films.

This paper presents a model of sublinearity of thermoluminescence (TL) dose response, based on the competitive interaction between active electron trapping centers and deep hole centers during excitation and heating of a phosphor. It is shown by analytical and numerical calculations that the sublinear response is observed at low doses, when the trap occupancy is far from saturation. It is found that the linearity index of TL dose response depends on the concentration of the deep hole traps, and on the coefficient of non-radiative electron recombination. The TL dose response is derived in parametric form. A new analytical expression is derived for the threshold doses, at which the TL response changes from a sublinear growth to an almost linear behavior. This phenomenon of a sublinear TL response changing into a linear behavior, is explained by the deep traps filling up to saturation. The dependence of the linearity index on the model parameters is found by numerical methods.

This paper presents a low-level liquid scintillation counting spectrometer with five identical counting units that allow simultaneous measurements to be performed. The counting chambers are enclosed in high purity copper and lead shielding which significantly decreases the background count rate. Each of the five counting chambers is equipped with a high stability software-controllable power supply, and each counting module contains a signal analyzer that measures the pulse height, pulse shape and the time between subsequent pulses, returning all the data as a time-stamped sequence which enables the identification of pulse pairs. Such pulse pairs, arising from the decay of 214 Bi/ 214 Po, provides a sensitive tool for 222 Rn contamination determination in low-level 14 C measurements. This enables radiocarbon dating or bio-component determination to be performed directly after liquid scintillator production without the risk of 222 Rn interfering with the measurement of 14 C.

In this paper, dosimetric phosphor; lithium tetraborate (Li 2 B 4 O 7 ) which has been synthesized and doped with Cu, Ag transition metals using two different synthesis methods (solution-assisted method and microwave-assisted method) and thermoluminescence characteristics of synthesized lithium tetraborate are analyzed. Synthesized Li 2 B 4 O 7 : Cu and Li 2 B 4 O 7 : Cu, Ag phosphors were characterized with X-ray Diffraction, Transmission Electron Microscopy, Scanning Electron Microscopy, and Differential Thermal Analysis to determine structural and morphological properties. Thermoluminescence (TL) properties of the lithium tetraborate samples, doped with varied amounts of copper in the range 0.02 wt% - 0.1 wt% and constant amount of silver (0.04 wt%) was added as co-dopant, were studied. TL results demonstrate that 0.08% Cu and 0.04% Ag doped lithium tetraborate synthesized with solution-assisted method has the highest dosimetric sensitivity. Kinetic parameters (trap depth and order of kinetic) of this sample were calculated using peak shape, variable heating rate and computer glow curve deconvolution methods.

Thermoluminescence (TL) glow curves from feldspar samples have been studied extensively in luminescence dating and dosimetry applications. However, the mechanism responsible for their unusual shape and behavior in preheated samples is not well understood. This paper presents new experimental TL glow curves for four types of preheated feldspar samples; an orthoclase, a sanidine and two microclines. Both the preheat temperature and the duration of the preheat are varied, before measurement of the remnant TL glow curve. Kinetic analysis of the experimental results is carried out using a recently proposed physical kinetic model which describes localized electronic recombination in a random distribution of donor-acceptor pairs, with nearest-neighbor interaction. The experimental data are analyzed using two different methods within the model. In the first method one follows the development of the distribution of nearest neighbor distances for each of the four stages of the experiment, namely irradiation followed by heating to a temperature and holding the sample at this temperature for certain time, and finally measurement of the TL glow curve. In the second method the TL glow curves are analyzed by using a single adjustable parameter in the model, which characterizes the thermal history of the sample. Good agreement is found between the two methods. However, the second method is much simpler to use in practical situations, and in principle it can be applied for any thermally or optically pretreated feldspar sample.

On silver halide (AgX) emulsion grains (∼200 nm in diameter) for neutrino detection in OPERA project, a latent image center composed of a cluster of ≧4 Ag atoms is formed with ∼18 electron-hole pairs by current photographic process in each grain. According to the analysis in this paper, AgX emulsion grains (∼40 nm) for dark matter detection should behave quite differently, forming a latent image center under such extraordinary condition that as many as ∼1000 electrons and surplus positive holes are created for ∼10 femtoseconds (fs) in each grain, causing violent recombination and re-halogenation of Ag clusters. Therefore, it is necessary to strongly reduce the recombination and re-halogenation of Ag clusters in the nuclear emulsions for dark matter detection. Further proposals are made on the design of nuclear emulsions for dark matter detection.

In the present paper the sensitivity V of plastic nuclear track detectors CR-39 to the space radiation, accelerated heavy ions in wide LET range and α-particles is studied. Different approaches for V evaluation are considered and compared. Main attention is given to the method that is appropriate for the measurement of short range heavy secondaries of space radiation. Finally, the experimental verification of the designed V function is carried out via simulation of the secondaries with low energy α-particles in the vicinity of the Bragg peak.

The main two trapping parameters in thermoluminescence (TL), the activation energy and the frequency factor, are often calculated and used for the evaluation of the stability of the TL signal at a given temperature. In several cases, “anomalous” values of these parameters, either very high or very low have been reported in the literature. In practically all of these cases, the values reported have been recognized to be effective values which resulted from some special circumstances related to the specific materials in hand. Obviously, these effective values are not associated directly with the real rate of thermal release of carriers from traps at the ambient temperature, prior to heating, and therefore, they do not indicate the real decay time of the TL signal or, in other words, the stability of the signal which may be used in TL dosimetry or dating of archaeological or geological samples. In the present paper, we discuss briefly some of these cases and add, in more detail, a rather elementary situation of very low effective activation energy and frequency factor. A model with two trapping states and one kind of recombination center is used and the simulation includes the numerical solution of the relevant sets of coupled differential equations in the three stages of the measurement, namely, excitation, relaxation and heating for a given set of the trapping parameters. The parameters are chosen in such a way that two overlapping TL peaks occur, which look together like a single first-order peak, but with anomalously low evaluated effective activation energy and frequency factor. Implications regarding the possible results in glow curve deconvolution are discussed.