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Abstract: An essential part of the laboratory procedure associated with optical dating is the irradiation of sample aliquots with known doses of ionizing radiation. Only if laboratory irradiation faithfully reproduces the effects (within the dating sample) of natural irradiation (during burial) will the dates obtained be accurate. Modelling of quartz luminescence suggests that the usual practice of administering laboratory doses at room temperature, and in single exposures, may lead to both equivalent-dose overestimation and increased levels of scatter in individual age estimates for samples with palaeodoses greater than 40Gy. In the model, this effect is due to the large differences between laboratory and natural dose rates. A modification to standard irradiation practices is suggested as a remedy to this problem, whereby laboratory regeneration doses are administered in 10Gy pulses, with the aliquot then being heated to 240°C following each pulse. Empirical measurements of 12 sedimentary samples support the theoretical findings, with significant differences in dose response being observed between single-irradiation and pulsed-irradiation OSL regeneration data. Results are also presented in which the problem of the laboratory dose response failing to reach the level obtained through natural irradiation is remedied by the pulsed-irradiation procedure. It is possible that the application of pulsed-irradiation regeneration may in future lead to a more accurate means of dating the deposition of quaternary sediments, although this remains to be demonstrated empirically by the dating of known-age samples. [Copyright &y& Elsevier]

The Total Skin Electron Beam (TSEB) irradiation is a radiotherapeutic technique that aims to provide the patient's skin surface with a more homogeneous dose, in order to treat cutaneous T-cell lymphomas, both for curative and palliative purposes. Electron irradiation penetrates a few millimeters into the skin, reaching the affected parts completely, without penetrating the internal organs. In vivo dosimetry has become an important role for the treatment of total skin irradiation within a rigorous quality assurance program that should be an integral part of the radiotherapy departments. The use of TLDs in vivo can identify variations in the prescribed dose because its measurement accuracy and great precision. The LiF:Mg,Ti is the most used TL material and widely studied in radiotherapy dosimetry due to near tissue-equivalence of the material, along with its overall reliability. The dosimeters of μLiF:Mg,Ti have been gaining considerable importance in the radiotherapy departments. These detectors allow measurements in vivo with great advantages due to their minimum dimensions of 1 × 1 × 1 mm 3 . This paper reports a comparative study of the TL responses of both materials to dose evaluation in TSEB treatments. The TL response of both materials in several TSEB parameter tests and in clinical application were evaluated, analyzing the dose distribution in a treatment simulation using AldersonRando anthropomorphic phantom. The results showed that the μLiF:Mg,Ti presented greater variation of the response in relation to LiF dosemeters in some parameters analyzed, due to the small dimensions and to evaluate doses absorbed in the surface over a large area in the treatment plan. • LiF:Mg,Ti TLdosimeters applied to TSEB six-dual-field parameter's evaluation. • μLiF:Mg,Ti TL dosimeters applied to TSEB compared with LiF:Mg,Ti. • LiF:Mg,Ti and μLiF:Mg,Ti TL results comparison. [ABSTRACT FROM AUTHOR]

Abstract A TEPC capable of simulating site sizes down to 25 nm was designed and constructed in order to fill the gap between nanodosimetry and experimental microdosimetry. In this paper, this device was proposed for assessing the quality of the therapeutic CATANA (INFN-LNS) proton beam. The detector was irradiated with a modulated 62 MeV proton beam and was placed at different depths across the spread-out of Bragg peak. For each position, several microdosimetric distributions for different simulated site size from 0.5 μm to 35 nm were acquired. The 0.5 μm spectra are in good agreement with spectra measured employing a reference TEPC in the same experimental conditions. The results show that, for bigger sites, microdosimetric distributions follow the slowing down of the primary particles, while, for smaller sites, they exhibit a bimodal shape, in particular at smaller depths in PMMA. The comparison between different simulated volumes shows an increment of the dose-averaged lineal energy with the reduction of the site. Moreover, a comparison between a ratio of the dose-averaged lineal energy for different simulates site sizes and the microdosimetric R B E shows that the smaller is the simulated volume, the better is the resembling of the microdosimetric R B E even if, the agreement is not yet fully reached for any site size. Finally, Monte Carlo simulations show that the electron energy threshold in FLUKA is too high for reproducing microdosimetric distributions for nanometric sites for proton beams. Highlights • Avalanche-confinement TEPC able to simulate site sizes down to nanometric region. • Nano-microdosimetric characterization of the CATANA proton beam line. • New methods for assessing the relative biological effectiveness of a proton beam. [ABSTRACT FROM AUTHOR]

This paper summarises recent developments in the Risø TL/OSL reader. These new developments include an elevated temperature irradiation facility that has been expanded to measure variable temperature radioluminescence (RL) during beta irradiation. This RL facility allows the measurement of TL, OSL and RL in the same software-controlled automatic sequence. To provide an alternative to the 90Sr beta source, the performance of a software-controlled mini X-ray generator has been investigated. This has the advantage of providing a range of dose rates spanning more than three orders of magnitude up to more than 2 Gy/s. A separate bleaching facility has also been added to the reader, new powerful infrared (IR) light-emitting diodes have replaced the IR laser diode in the general OSL unit, and an IR laser has been included in the single-grain OSL attachment. This paper describes these new facilities, and illustrates their applications with representative measurements. [Copyright &y& Elsevier]

Abstract 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. Highlights • Experimental and theoretical calibration of CR-39 and Makrofol detectors were done. • V function for Makrofol was presented. • Previously developed software was modified to enable Makrofol calibration. • Optimisation of chamber and detector dimensions was theoretically performed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The tissue equivalent proportional counter (TEPC) is the most accurate device for measuring the microdosimetric properties of a particle beam, showing to assess the relative biological effectiveness by linking the physical parameters of the radiation field with the corresponding biological response. Nevertheless, no detailed information on the track structure of the impinging particles can be obtained, since the lower operation limit of the common TEPCs is about 0.3 μm. On the other hand, the pattern of particle interactions at the nanometer level, which demonstrated to have a strong correlation with radiation-induced damages to the DNA, is measured directly by only three different nanodosimeters worldwide: practical instruments are not yet available. The gap between microdosimetry and track-nanodosimetry can be filled partially by extending the TEPC response down to the nanometric region. A feasibility study of a novel TEPC designed to simulate tissue-equivalent sites in the nanometric domain was performed. The present paper aims at describing the design, the development and the characterization of this avalanche-confinement TEPC. Irradiations with photons, fast neutrons and low-energy carbon ions demonstrated the capability of this TEPC of measuring in the range 0.3 μm–25 nm. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Extended Bonner Spheres spectrometer was used to measure the angular distribution of neutron spectral fluence around NYLON6 phantom irradiated with pencil beam of 100, 150 and 200 MeV protons at the Proton Therapy Center Praha. Measurements were supplemented by a calculation of neutron spectral fluences at different depths of the phantom. The calculation of neutron spectral fluence at different depth of the phantom demonstrated that the majority of high energy neutrons was generated at the beginning of the proton trajectory in the phantom and the neutron yield decreased with increasing depth, with a minimum at the depth corresponding to the Bragg peak. Therefore, attention should be paid not only to the tissue behind the irradiated volume, but also to the preceding tissue. However, the neutron spectral fluence in the vicinity of the treated tissue can only be determined by calculation, mainly due to the dimensions of the neutron spectroscopic instrumentation. This paper presents a suitable technique and experimental conditions to acquire reliable data necessary for the proper determination of neutron spectral fluence. From the measured spectral fluences, the neutron fluence in whole-range and partial energy intervals were determined together with the corresponding ambient dose equivalents at measurement positions. The obtained results indicate that high energy neutrons predominate at the direction of the proton beam and more neutrons are generated by higher energy protons. [ABSTRACT FROM AUTHOR]

In the present paper the formation of defects in LiKSO 4 andK 2 SO 4 crystals after excitation by 4–11 eV photons at the temperature of liquid nitrogen was studied by the methods of thermal activation and vacuum-ultraviolet spectroscopy. It is shown experimentally that electron-hole trapping centers are formed as a result of capture of electrons and holes by anion complexes S O 4 2 − created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to the s-state of the cation in the conduction band. It is supposed that the formation of defects in LiKSO 4 and K 2 SO 4 crystals is caused by the dissociation of excited anion complexes, created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to free, antibinding orbitals 4 t 2 ∗ and 3 a 1 ∗ in the conduction band. In this case, stable electron S O 3 − v a + e − and hole O 3 − trapping centers are formed. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the effect of 8 MeV of electron beam (EB) energy irradiation on the electrical conductivity and dielectric properties of sodium fluoride NaF-doped polyethylene oxide (PEO) film. The structural and chemical characterizations were employed using X-ray diffractometry (XRD) and Fourier Transform Infrared (FTIR) techniques respectively before and after irradiation. The morphology study carried out using Scanning Electronic Microscopy (SEM) analysis. The DC electrical conductivity showed increases with dose and temperature and was consistent with Arrhenius behavior. The maximum conductivity of 1.1 × 10−5 S/cm and minimum activation energy of 0.25 eV were obtained at 25 kGy, 338 K; further increases in the dose resulted in a reduction in conductivity. The real (ε′) and imaginary (ε″) part of the dielectric constant suddenly decreased in a low frequency region (40–640 Hz), subsequently independent at higher frequency. The AC conductivity showed increases with frequency and temperature for all films. The dielectric constant and AC conductivity increased at the 25 kGy dose due to chain scission. Further increases in dose such as 50 and 75 kGy, resulted in a decrease in dielectric constant and AC conductivity due to cross-linking. The electric modulus approach was used to calculate the dielectric relaxation time (τ), which decreased at 25 kGy and then increased at 50 and 75 kGy doses. The modulus data were fitted using a non-exponential Kohlrausch–Williams–Watts (KWW) function ϕ (t), and the results indicate the existence of a non-Debye relaxation. [Copyright &y& Elsevier]

Abstract: This paper investigates the influence of activator concentration and temperature on the scintillation process in CsI:Na crystal which was excited by a pulsed electron beam (Eex = 0.25 MeV, t 1/2 = 15 ns, W = 0.003…0.16 J/cm2) at temperature within 77–300 K. It has been established that the transition of Na-bound two halide exciton from singlet state causes 3 eV emission of CsI:Na. The capturing of Vk by Na+ ion determines the scintillation pulse shape. Thermal liberation of Vk from VkA centers results in an inertial rise of the emission pulse in lightly activated CsI:Na and in a mono-exponential decay of the emission pulse in heavily activated CsI:Na. The value of thermal dissociation energy of VkA centers is 0.24 ± 0.01 eV, which was obtained from the temperature dependences of the emission decay time constant for CsI:2.8∙10−3%Na and of the rise time constant for CsI:2.0∙10−4%Na. [Copyright &y& Elsevier]

LiF crystal doped with magnesium (Mg), copper (Cu) and phosphorous (P) was grown in the form of multicrystalline sheet using Edge-defined film-fed growth (EFG) technique for dosimetry application. These crystals were grown in argon gas atmosphere using graphite crucible and stainless steel die. Dosimetry peak was observed at 210 °C for as-grown crystal. As reported earlier LiF:Mg, Cu, P is a highly sensitive material but losses its sensitivity if annealed at temperature above 240 °C. In this paper, the effect of annealing temperature on thermoluminescence glow-curve structure, maximum peak temperature, peak height and integrated area of the glow peak of EFG grown samples was investigated in detail. Annealing temperature range from 220 °C to 500 °C was considered for the study. Experimental results of the obtained glow curve show that with increase in annealing temperature, glow peak shift towards higher temperature region with substantial increase in TL intensity. Annealing at 500 °C for 10 min gave maximum TL intensity with main dosimetry peak positioned at 233 °C. Change in the defect structure with different pre-annealing temperature was analysed using trapping parameters. [ABSTRACT FROM AUTHOR]

Abstract: This paper gives a review of recent developments in luminescence measurement facilities on the Risø TL/OSL reader including radio-luminescence (RL), exo-electron and violet stimulation attachments, and a method for characterising and if necessary correcting for beta irradiation source non-uniformity. We first describe improvements to the existing RL option to allow near infra-red detection (NIR) during irradiation by the built-in 90Sr/90Y beta source. The RL optical signal is collected by a liquid light guide through an F34-901 interference filter and detection is based on a dedicated thermoelectrically cooled NIR sensitive PMT (detection window peak at 855 nm, FWHM 27 nm). Software and electronics have been modified to allow standard TL and OSL measurements in the same sequence as RL measurements. Together with a new bleaching source based on a high-power UV LED (395 nm; 700 mW/cm2), this facility has been used to measure natural doses in feldspar using the decaying NIR RL signal. Secondly, we present a method for mapping radiation field of the built-in 90Sr/90Y β-source and estimating grain-location specific dose-rates. This is important for the accuracy of single grain results, when radiation field is spatially non-uniform across the sample area. We document the effect of this correction method and further investigate on the effect of lifting the source to achieve a better dose-rate uniformity. Finally we summarise two recently-developed novel facilities to help investigate (i) the time scales involved in OSL processes (time-resolved exo-electron detection) and (ii) extending the age range (violet stimulated signals from deep quartz OSL traps). [Copyright &y& Elsevier]

Abstract: The effects of high Frequency (HF) progressive ultrasonic wave on the F-centers in KCl single crystals are discussed in this paper. Ultrasonics of 3 MHz and 9 MHz are used in the present investigation to produce strain wave perturbation on the F-centers. The thermoluminescence (TL) glow curves obtained from X-irradiated normal and strain wave exposed KCl single crystals show two peaks. In the TL glow curves recorded from X-irradiation followed by the ultrasonic wave exposure of KCl single crystals result in the shift of these peaks to higher temperature side with an increase in their separation and a change in relative areas. However, no additional peaks were seen. Apart from this the strain wave perturbation was also found to effect trapping parameters. [Copyright &y& Elsevier]

Abstract: Systematic measurements of swelling of CR-39 nuclear track detector (NTD) due to irradiation with fission fragments and alpha particles over a wide range of fluences from 252Cf are presented here. Precisely designed and optimized exposure and chemical etching experiments were employed to unfold the structure of radiation induced surface damage. Delays in the startup of the chemical etching of latent tracks in low radiation fluence detectors are measured and are found to contain important information about structure of the surface damage. Simple atomic scale pictures of radiation induced surface damage and its chemical etching are developed using measurements of radiation induced swelling of CR-39 detectors and nuclear track parameters. The computer code SRIM2010 was utilized for the calculations of basic features of latent tracks of fission fragments and alpha particles in CR-39. Another computer code TRACK_VISION was used to compute parameters of etched tracks. Computations and experimental findings in the paper coherently compose a realistic picture of radiation damage. [Copyright &y& Elsevier]

Abstract: Mixed Alkali halide crystals containing KBr and NaI in different compositions were grown by slow evaporation technique. Obtained transparent crystals were doped with gold to study the role of dopant on the mixed crystals. Crystals were subjected to 60Co γ-radiation. The irradiated samples were subjected to Thermoluminescence, Optical Absorption and Electron Spin Resonance studies. Effect of Au+ doping on TL intensity and absorption coefficient is discussed in the present paper. [Copyright &y& Elsevier]

Abstract: The use of optically stimulated luminescence (OSL) in radiation dosimetry has been conditioned by the availability of suitable dosimetry (OSLD) materials. The crucial property dictating the suitability of a material as an OSLD is the material’s defect structure. This paper reviews some of the recent developments in radiation dosimetry that have been enabled by knowledge of the charge trapping and recombination processes occurring in OSLD materials during irradiation and stimulation. Although many materials have been and are currently being studied, this short review focuses on just two, namely carbon-doped aluminum oxide (Al2O3:C) and europium-doped potassium bromide (KBr:Eu). The defect structure and trapping/recombination mechanisms in these materials have led to application in several areas of radiation dosimetry and dose imaging. Two recent areas of development are in space dosimetry (for Al2O3:C) and in medical dosimetry (for KBr:Eu). This overview briefly describes these latter modern applications and relates the functionality of the OSLDs to their basic defect properties. [Copyright &y& Elsevier]

Abstract: In this paper the EPR spectra of the radicals induced in oyster shells after irradiation to (0.5–2) kGy ionizing radiation doses are analyzed. EPR spectra of irradiated shells showed the complex radical composition of biocarbonates, characterized by the presence of SO2 −, SO3 − and CO2 − radicals with different symmetries. In particular, the radiation-induced line at g = 2.0038, due to the gx component of the orthorhombic SO3 −, was well distinguishable from the rest of the spectrum. The gx component of the orthorhombic SO3 − was found to be intense and stable enough to allow the identification at least for the whole shelf life of the oyster. Furthermore, it is still well visible at low microwave powers for which the other signals are weak or non-visible and has a linear dose response in the (0.5–2) kGy range. A possible procedure protocol for the identification of irradiated oysters, can be based on acquisitions of the spectrum at low microwave power values (tenths of milliWatt) and low modulation amplitude values (0.03–0.05 mT) and on the identification of the g = 2.0038 signal as a proof of the ionizing radiation treatment performed on the sample. [Copyright &y& Elsevier]

Abstract: This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum München. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers. [Copyright &y& Elsevier]

Abstract: This paper was intended as a study of the radiological characteristics of a polymer gel detector in a clinical proton beam irradiation. The depth dose distributions in the detector were examined with regard of dose and dose rate dependences in the response. Our experimental results indicated that the dose response depended considerably on the depth from the incident position, and also the dose rate in the proton irradiation. We estimated the dose response at different depth of the incident proton beam from the depth-R 2 relations with various dose, and the spread-out depth dose in a single field irradiation derived from these dose responses obtained the good agreement with a planned dose distribution. In conclusion, our method with MAGAT type polymer gel is effective in a quality assurance of fundamental reproducibility test for three dimensional radiation therapy planning system, such as monitor unit verification and standard isodose verification using a single field proton beam. However the depth dose distribution should be evaluated depending on irradiation dose rate, SOBP width, and maximum energy. [ABSTRACT FROM AUTHOR]

Abstract: Well known, widely applied high sensitive thermoluminescence (TL) detector LiF:Mg,Cu,P (MCP-N) was investigated. This paper analyses changes of the TL emission spectrum of MCP-N after irradiation with ultra high doses (up to 500 kGy). Spectral dependence of TL on dose is very complex especially in the region of very high doses (>1 kGy). As a general trend we found that the number of peaks increases with dose in the long-wavelength region indicating new types of recombination centres (RCs). Wavelength peak positions for increasing doses are quite stable. Only some of them show slight red-shift. [Copyright &y& Elsevier]

Abstract: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900°C, beta irradiation dose as high as 1700Gy, and temperature of stimulation up to 200°C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of ∼35μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18μs when the annealing temperature is changed from 600 to 900°C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to report the sensitization of the TL peak appearing at 270°C in the glow curve of natural quartz by using the combined effect of heat-treatments and irradiation with high doses. For this, thirty discs with were prepared from plates parallell to a rhombohedral crystal face. The specimens were separated into four lots according to its TL read out between 160 and 320°C. One lot was submitted to doses of 60Co radiation starting at 2kGy and going up until a cumulative dose of 25kGy. The other three lots were initially heat-treated at 500, 800 and 1000°C and then irradiated with a single dose of 25kGy. The TL response of each lot was determined as a function of test-doses ranging from 0.1 to 30mGy. As a result, it was observed that heat-treatments themselves did not produce the strong peak at 270°C that was observed after the administration of high doses. This peak is associated with the optical absorption band appearing at 470 nm which is due to the formation of [AlO4]° acting as electron–hole recombination centers. The formation of the 270°C peak was preliminary analyzed in relation to aluminum- and oxygen-vacancy-related centers found in crystalline quartz. [Copyright &y& Elsevier]

Abstract: Microscopic glass slides are soda-lime glasses which are readily available and are easy to manufacture with low production cost. The application of these glasses as nuclear track detector will help us to make use of these glasses as solid-state nuclear track detector. The present paper describes the variation in the etching, optical and structural properties of the soda-lime microscopic glass slides due to neutron irradiation of different fluences. The color transformation and an increase in the optical absorption with neutron irradiation are observed. Both the bulk and track etch rates are found to increase with neutron fluence, thus showing a similar dependence on neutron fluence, but the sensitivity remains almost constant. [Copyright &y& Elsevier]

Abstract: In this paper, we review existing methods for long-term measurements of radon decay products with solid-state nuclear track detectors. We then propose a method to determine the equilibrium factor using the bare LR 115 detector. The partial sensitivities of the LR 115 detector to and its -emitting short-lived progeny, and , were investigated. We determined the distributions of lengths of major and minor axes of the perforated -tracks in the LR 115 detector produced by , and through Monte Carlo simulations. The track parameters were first calculated using a track development model with a published function, and by assuming a removed active layer of . The distributions determined for different -emitters were found to be completely overlapping with one another. This implied equality of partial sensitivities for radon and its progeny. Equality of partial sensitivities makes convenient measurements of a proxy equilibrium factor possible which is defined in the present work as and is equal to the ratio between the sum of concentrations of the two -emitting radon progeny to the concentration of radon gas . In particular, we have found , where (track/m2) is the total track density on the detector, (for the function mentioned above and for a removed active layer of ), is the exposure time and (Bq/m3) is the concentration of . If is known (e.g., from a separate measurement), we can obtain . The proxy equilibrium factor is also found to be well correlated with the equilibrium factor between radon gas and its progeny through the Jacobi room model. This leads to a novel method for long-term determination of the equilibrium factor. Experimental irradiation of LR 115 detectors to known concentrations as well as known equilibrium factors were carried out to verify the present method. The relationship between and the removed layer was then derived for the function specifically determined for the LR 115 detectors we were using for the experiments. The actual removed layers for individual detectors after etching were measured accurately using surface profilometry. A curve showing the relationship between the removed layer and the track diameter of normally incident 3MeV -particles is also provided for other researchers, who do not have access to surface profilometry, to use the present technique conveniently. [Copyright &y& Elsevier]

In recent years, the number of experiments related to the simulation of chemical reactions induced by radiation, that may take place in the interstellar medium, is growing very fast. To have a quantitative picture of the changes observed in those systems, a low-temperature dosimeter is needed. The aim of this paper is to search for a dosimetric system that can be used in those laboratory simulation experiments. Three systems were used in this study, (1) LiF:Mg,Cu,P, (2) CaSO4: Dy and (3) ferrous sulfate in frozen aqueous solution. There is a considerable effect in their behavior in relation to the irradiation temperature. The results for the two TL dosimeters show that their responses are dependent on the irradiation temperature. At low-radiation dose the response was linear with the dose (10–600 Gy). For the case of iron salt the response was linear in the range used (0–600 Gy). Numerical simulations fit the experimental data obtained with this dosimeter. [Copyright &y& Elsevier]

This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20–50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100–1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800–875 K, along with a concomitant decrease in the concentration of recombination centers (F+-centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed. [Copyright &y& Elsevier]

ThO2–PuO2 mixed oxide (MOX) experimental fuel pins have been fabricated at Bhabha Atomic Research Centre, for irradiation experiments as a part of an advanced fuel development programme. During the quality control of fuel pellets, the homogeneous distribution of the fissile plutonium in them has been ascertained using alpha autoradiography and gamma autoradiography techniques. The quantitative estimation of the plutonium-rich regions of the pellets has been carried out by optical microdensitometry and digital image analysis. This paper discusses the implementation of the techniques and presents a few typical results. [Copyright &y& Elsevier]

The modification of thin layer interfaces by ion irradiation (ion beam mixing) is the most elegant way to learn about the atomic transport processes induced by the energy deposited along the ions path. Ion beam mixing in the nuclear stopping regime has been intensively studied for about 30 years, while ion beam mixing by electronic energy deposition became a matter of interest only after about 1993. In this paper an attempt will be made to briefly summarise the present knowledge on atomic transport processes induced by the electronic energy loss of swift heavy ions on the basis of our recent ion beam mixing experiments with layered systems. Swift heavy ion beam mixing is strongly related to nuclear track formation and therefore a short introduction into the present ideas of the ion''s energy deposition and the track formation processes will be given. Afterwards the few experiments on high-energy ion beam mixing performed until recently will be shortly reviewed. Finally we will discuss in detail our mixing data in ceramic systems and show that swift heavy ion beam mixing is a threshold process and results from transient interdiffusion in the molten ion track. [Copyright &y& Elsevier]

Abstract: This paper discussed the neutron doses induced by the high energy medical linear accelerator (Linac). Thermoluminescent dosimeter (TLD) pairs are usually chosen to distinguish the doses of neutrons from photons in mixed radiation field. In this work, TLD-600 and TLD-700 chips were used to investigate the dose contributions of neutrons induced by 15 MV photon beam of the medical Linac used in radiotherapy. A Rando phantom filled with these dual-TLD chips was irradiated in the 15 MV photon beam to assess the doses contribution of the induced neutrons. Besides, dual-TLD chips were also placed in the treatment room to estimate the spatial dose distribution of neutrons. In the results, dose contributions of neutrons in phantom are less than 0.1% compared with the maximum dose of photons. The dose distribution of neutrons in the treatment room was also revealed. [Copyright &y& Elsevier]

Abstract: The high temperature thermoluminescence (HTTL) in the glow curve of LiF:Mg,Ti (TLD-100) is of continuing interest due to the dependence of the HTTL on ionization density. Following high ionization density irradiation, the intensity of the HTTL relative to peak 5 is much greater than the same ratio following low ionization density irradiation. Special attention has focused on the details of the linearity/supralinearity of the HTTL dose response at levels of dose between 10 and 500 mGy and whether the batch history (previous irradiation and annealing) affects the HTTL dose response? In this paper we demonstrate that batch identity leads to differences of ∼100% in the degree of the supralinearity of the dose response of peak 7 between two groups of TLD-100 chips. The results suggest that there may be significant non-universalities in the HTTL dose response and that further research is required to provide a sound basis for the use of the HTTL of TLD-100 in dosimetric applications. [Copyright &y& Elsevier]

Abstract: A new method of thermoluminescent (TL) measurement of radiation doses ranging from micrograys up to a megagray has been recently developed at IFJ. This method is based on a newly discovered behavior of LiF:Mg,Cu,P detectors at doses exceeding 1 kGy. Significant changes in their glow-curves are observed at higher doses; of special importance is occurrence of a new, well separated peak for doses above 50 kGy, thus these detectors can be used for measurements of doses at ultra-high dose range. In order to check the glow-curve features in the high dose region for different types of LiF:Mg,Cu,P and LiF:Mg,Ti detectors after irradiation with heavy charged particles, tests at the 24 GeV/c proton beam of IRRAD1 irradiation zone at the CERN Proton Synchrotron accelerator up to 1 MGy were performed. The occurrence of the high dose peak in the glow-curve of LiF:Mg,Cu,P detectors resulting from heavy particles irradiation was confirmed. Results of this investigation are presented in this paper. [Copyright &y& Elsevier]

Abstract: This paper describes results of experimental studies on radiation defects in nominally pure single crystals of corundum in two initial states: α-Al2O3 with an unperturbed lattice and α-Al2O3:C with a high concentration of anion vacancies. Defects were identified from optical absorption spectra, ionoluminescence, pulsed cathodoluminescence and photoluminescence spectra. It is shown that mostly color centers of the F- and F+-types are formed in the α-Al2O3 lattice under irradiation with 5,7MeV protons. [Copyright &y& Elsevier]

Abstract: The SrAl2O4:Eu2+, Dy3+ is a phosphor characterized by a long persistent luminescence (PLUM) when it is excited with UV–VIS light and ionizing radiation. In this paper, we study the PLUM behavior as a function of beta irradiation dose in the 0–650 Gy range with a fixed dose rate of 5 Gy/min. The PLUM intensity showed a complex decay behavior, exhibiting a near linear response in the 0–1.7 Gy low dose range and gradually increasing up to 160 Gy. The PLUM reached the saturation for higher doses (>275 Gy) with a slight decrease in the range of 300–650 Gy. In addition, a systematic PLUM enhancement was produced after a thermal cleaning procedure and irradiation at RT in a series of 10 cycles. The observed phenomenon may be related to a radiation-induced process of charge trapping accumulation, which is triggered by thermal stimulation during the irradiation stage. It improves the luminescent characteristics of SrAl2O4:Eu2+, Dy3+ phosphors rendering them suitable for permanent display and illumination devices. [Copyright &y& Elsevier]

This work aims at assessing the performance of a235U enriched fission chamber in order to localize fuel debris, prior to dismantling operations, in a flooded primary containment vessel of a damaged nuclear reactor such as Fukushima Daiichi. Based on both a comprehensive scan of the environment and the detection of neutrons emitted by the melted core, fuel debris can be localized. In this paper, we carry out a simulation study using the MCNP6 code to investigate fission chamber response in the frame of fuel debris localization measurements in a damaged nuclear reactor. The CFUF34 fission chamber (manufactured by PHOTONIS) and the primary containment vessel of Fukushima Daiichi Unit 1 were chosen to conduct this work. Impact of different parameters were investigated with MCNP6, such as: neutron energy, water temperature, fission chamber position (altitude, lateral shift, and rotation), and sensitivity loss due to sediments potentially covering fuel debris. In summary, we show that fuel debris should be sought by their thermal neutron signature at a distance of a few centimeters and that potential rotational movements of the fission chamber up to 60° have a limited impact on signals measured. We also show that sensitivity loss due to sediments potentially covering fuel debris has been evaluated on the order of a factor 10 considering a 30 cm-thick sediment layer. On the other hand, experiments were performed to assess the impact of a strong gamma dose rate on fission chamber measurements. These irradiation trials involved a CFUE32 fission chamber (also manufactured by PHOTONIS) available in our laboratory and three different irradiation means: an X-ray tube, an 192Ir source, and a linear electron accelerator. These experiments enable to draw the conclusion that the fission chamber is not impacted by the gamma dose rate up to 104 Gy h−1, which is in good agreement with specifications provided by the manufacturer (PHOTONIS). In addition, no performance degradation was observed after an integrated gamma dose of 2200 Gy on the fission chamber in a 10 min irradiation. However, when the fission chamber is irradiated by gamma dose rates above 104 Gy h−1 (upper limit of the operating domain specified by PHOTONIS), a significant gamma background is observed. Nevertheless, as the gamma dose rates at Fukushima Daiichi should not exceed 103 Gy h−1, fission chamber measurements performed towards fuel debris localization in the primary containment vessels of the units would not be affected by the severe gamma-ray irradiation. • Investigation of fission chamber response in the frame of fuel debris localization measurements by MCNP6 simulation study. • Fuel debris sought underwater by their thermal neutron signature at a distance of a few centimeters. • Sensitivity loss on the order of a factor 10 considering a 30 cm-thick sediment layer on the top of fuel debris. • Experiments to assess the impact of strong gamma dose rates on fission chamber measurements. • No impact of gamma dose rates up to 104 Gy h−1. Beyond, the fission chamber registers a significant gamma background. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper correlation between track etch properties like track diameter, track etch rate and detection sensitivity with the density of free radicals in irradiated PADC are examined and discussed. The density of free radicals produced by irradiation with light charged particles has been studied in dependence on the temperature and the oxygen concentration by using the electron-spin-resonance (ESR) method. The influences of both environmental parameters on the density and the lifetime of the radicals are strongly correlated with the dependence of important track etch properties. The investigations have been performed for PADC of types TASTRAK and BARYOTRAK. [Copyright &y& Elsevier]