Search

The aim of this study was to experimentally assess the luminescence efficiency of a cerium fluoride (CeF3) inorganic scintillator in crystal form as a possible alternative to high-luminescence but hygroscopic cerium bromide (CeBr3). The experiments were performed under typical diagnostic radiology X-rays (50–140 kVp). Parameters such as the crystal's absolute luminescence efficiency (AE) and the spectral matching with a series of optical detectors were examined. The replacement of bromine with fluorine appeared to drastically reduce the AE of CeF3 compared to CeBr3 and other commercially available inorganic scintillators such as bismuth germanate (Bi4Ge3O12-BGO). CeF3 reaches a maximum luminescence efficiency value of only 0.8334 efficiency units (EUs) at 140 kVp, whereas the corresponding values for CeBr3 and BGO were 29.49 and 3.41, respectively. Furthermore, the emission maximum (at around 313 nm) moved towards the lower part of the visible spectrum, making CeF3 suitable for spectral coupling with various photocathodes and photomultipliers applied in nuclear medicine detectors, but completely unsuitable for spectral matching with CCDs and CMOS. The obtained luminescence efficiency results denote that CeF3 cannot be applied in medical imaging applications covering the range 50–140 kVp; however, examination of its luminescence output in the nuclear medicine energy range (~70 to 511 keV) could reveal possible applicability in these modalities. [ABSTRACT FROM AUTHOR]

The reduction in the effective dose of evacuated injured persons through contaminated areas of nuclear accidents is an essential emergency services requirement. In this context, there appeared a need to develop a dose-optimised route finding method for firefighting rescue vehicles, which includes the development of a real-time decision support measurement and evaluation system. This determines and visualises the radiation exposure of possible routes in a tested area. The system inside and outside of the vehicle measures the ambient dose equivalent rate, the gamma spectra, and also the airborne radioactive aerosol and iodine levels. The method uses gamma radiation measuring NaI(Tl) scintillation detectors mounted on the outside of the vehicle, to determine the dose rate inside the vehicle using the previously recorded attenuation conversation function, while continuously collecting the air through a filter and using an alpha, beta, and gamma radiation measuring NaI(Tl)+ PVT + ZnS(Ag) scintillator to determine the activity concentration in the air, using these measured values to determine the effective dose for all routes and all kinds of vehicles. The energy-dependent shielding effect of the vehicle, the filtering efficiency of the collective protection equipment, and the vehicle's speed and travel time were taken into account. The results were validated by using gamma point sources with different activity and energy levels. The measurement results under real conditions and available real accident data used in our simulations for three different vehicles and pedestrians proved the applicability of the system. During a nuclear accident based on our model calculations, the inhalation of radioactive aerosols causes a dose almost an order of magnitude higher than the external gamma radiation caused by the fallout contamination. The selection of the appropriate vehicle and its route is determined by the spectrum that can be measured at the accident site but especially by the radioactive aerosol concentration in the air that can be measured in the area. In the case of radiation measuring detectors, the shielding effect of the carrier vehicle must be taken into account, especially in the case of heavy shielding vehicles. The method provides an excellent opportunity to reduce the damage to the health of accident victims and first responders during rescue operations. [ABSTRACT FROM AUTHOR]

Eu:CaHfO3 single crystals with various Eu concentrations were synthesized by the floating zone method, and their photoluminescence (PL) and scintillation properties were investigated. All the samples showed PL peaks at 590, 620, and 650 nm, which were due to the 4f-4f transitions of Eu3+. The PL quantum yield of 1.0% Eu:CaHfO3 was the highest at 42.2% among the samples. The X-ray-induced scintillation spectra showed several emission peaks in the range of 400-690 nm, and the emissions were attributed to the 4f-4f transitions of Eu3+. Among the samples, 0.05% Eu:CaHfO3 showed the highest intensity. In the afterglow curves, the levels were within the range of 1,000-10,000 ppm and those of previous studies. [ABSTRACT FROM AUTHOR]

In this paper, we report the first Bi4Ge3O12-based thin-layer alpha radiation detector. The scintillator was immobilized on a fused silica substrate via pulsed laser irradiation of BGO powder consisting of submicron particles. Laser treatment conditions were shown to influence the morphology and kinetic characteristics of the scintillator. The material we prepared ensures a higher stability of detectors to moisture and air in comparison with its commercially available analogs, while offering a comparable or even higher detection efficiency, and can be used in environmental monitoring, including volumetric alpha activity measurements. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskite single crystals (SCs) are promising materials for detecting ionizing radiation owing to their outstanding photoelectric conversion capability and inexpensive solution processability. However, the accuracy and stability of the detectors have been limited due to the charge traps and defects in SCs, especially when operated under high‐precision photon‐counting mode for energy spectrum acquisition. Here, we proposed a trap freezing deactivation route, which obviously suppressed dark current and noise by up to 97% and 92%, respectively. Furthermore, the bulk ion migration effect was essential for the ability to instantly self‐heal defects induced by radiation damage at temperatures down to −30°C. Consequently, the detector exhibits a record high energy resolution of 7.5% at 59.5 keV for 241Am γ‐ray source, which is the best solution‐processed semiconductor radiation detectors at the same energy range. In addition, the detector maintains over 90% of its initial performance after 9 months of storage when tested in the air. Our results will represent a revision of the paradigm that high‐spectral‐resolution and robust radiation detectors can only be realized with high temperature grown inorganic semiconductor single crystals. [ABSTRACT FROM AUTHOR]

Gallium nitride is a wide-direct-bandgap semiconductor suitable for the creation of modern optoelectronic devices and radiation tolerant detectors. However, formation of dislocations is inevitable in MOCVD GaN materials. Dislocations serve as accumulators of point defects within space charge regions covering cores of dislocations. Space charge regions also may act as local volumes of enhanced non-radiative recombination, deteriorating the photoluminescence efficiency. Surface etching has appeared to be an efficient means to increase the photoluminescence yield from MOCVD GaN materials. This work aimed to improve the scintillation characteristics of MOCVD GaN by a wet etching method. An additional blue photo-luminescence (B-PL) band peaking at 2.7–2.9 eV and related to dislocations was discovered. This B-PL band intensity appeared to be dependent on wet etching exposure. The intensity of the B-PL was considerably enhanced when recorded at rather low temperatures. This finding resembles PL thermal quenching of B-PL centers. The mechanisms of scintillation intensity and spectrum variations were examined by coordinating the complementary photo-ionization and PL spectroscopy techniques. Analysis of dislocation etch pits was additionally performed by scanning techniques, such as confocal and atomic force microscopy. It was proved that this blue luminescence band, which peaked at 2.7–2.9 eV, is related to point defects those decorate dislocation cores. It was shown that the intensity of this blue PL band was increased due to enhancement of light extraction efficiency, dependent on the surface area of either single etch-pit or total etched crystal surface. [ABSTRACT FROM AUTHOR]

LIDAL (Light Ion Detector for ALTEA, Anomalous Long-Term Effects on Astronauts) is a radiation detector designed to measure the flux, the energy spectra and, for the first time, the time-of-flight of ions in a space habitat. It features a combination of striped silicon sensors for the measurement of deposited energy (using the ALTEA device, which operated from 2006 to 2012 in the International Space Station) and fast scintillators for the time-of-flight measurement. LIDAL was tested and calibrated using the proton beam line at TIFPA (Trento Institute for Fundamental Physics Application) and the carbon beam line at CNAO (National Center for Oncology Hadron-therapy) in 2019. The performance of the time-of-flight system featured a time resolution (sigma) less than 100 ps. Here, we describe the detector and the results of these tests, providing ground calibration curves along with the methodology established for processing the detector's data. LIDAL was uploaded in the International Space Station in November 2019 and it has been operative in the Columbus module since January 2020. [ABSTRACT FROM AUTHOR]

(1) Background: The IVIscan is a commercially available scintillating fiber detector designed for quality assurance and in vivo dosimetry in computed tomography (CT). In this work, we investigated the performance of the IVIscan scintillator and associated method in a wide range of beam width from three CT manufacturers and compared it to a CT chamber designed for Computed Tomography Dose Index (CTDI) measurements. (2) Methods: We measured weighted CTDI (CTDIw) with each detector in accordance with the requirements of regulatory tests and international recommendations for the minimum, maximum and the most used beam width in clinic and investigated the accuracy of the IVIscan system based on the assessment of the CTDIw deviation from the CT chamber. We also investigated the IVIscan accuracy for the whole range of the CT scans kV. (3) Results: We found excellent agreement between the IVIscan scintillator and the CT chamber for the whole range of beam widths and kV, especially for wide beams used on recent technology of CT scans. (4) Conclusions: These findings highlight that the IVIscan scintillator is a relevant detector for CT radiation dose assessments, and the method associated with calculating the CTDIw saves a significant amount of time and effort when performing tests, especially with regard to new CT technologies. [ABSTRACT FROM AUTHOR]

Additive manufacturing techniques enable a wide range of possibilities for novel radiation detectors spanning simple to highly complex geometries, multi-material composites, and metamaterials that are either impossible or cost prohibitive to produce using conventional methods. The present work identifies a set of promising formulations of photocurable scintillator resins capable of neutron-gamma pulse shape discrimination (PSD) to support the additive manufacturing of fast neutron detectors. The development of these resins utilizes a step-by-step, trial-and-error approach to identify different monomer and cross-linker combinations that meet the requirements for 3D printing followed by a 2-level factorial parameter study to optimize the radiation detection performance, including light yield, PSD, optical clarity, and hardness. The formulations resulted in hard, clear, PSD-capable plastic scintillators that were cured solid within 10 s using 405 nm light. The bestperforming scintillator produced a light yield 83% of EJ-276 and a PSD figure of merit equaling 1.28 at 450-550 keVee. [ABSTRACT FROM AUTHOR]

Scintillators have long been known as radiation detectors and are still used in various applications. Recently, scintillators containing 6Li have been developed as neutron detectors and have attracted attention. 6Li absorbs thermal neutrons and emits α+3H, which is promising as a neutron detector if it can be separated from background gamma rays. We have been developing Eu:LiI–CaI2-based scintillators (Eu:LiCaI) for this purpose. In scintillator detectors, waveform information is generally used to distinguish particles such as neutrons and gamma rays. We propose a new particle identification method using emission wavelength information. In this study, experiments were conducted using Eu:LiCaI crystals, multi-pixel photon counter optical sensors, and long-wavelength cut filters to verify the proposed method. The results of irradiating a 252Cf neutron source and a 60Co gamma-ray source indicate that there is a particle dependence on the output signal ratio with and without filters. This indicates that different types of radiation particles have different emission wavelengths. This is the first demonstration of a wavelength-based particle identification method. [ABSTRACT FROM AUTHOR]

The Nd-doped LaMgAl11O19 single crystals were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, several sharp emission peaks due to the 4f–4f transitions of Nd3+ were observed at 900, 1060, and 1340 nm in the near-infrared range, and the decay curves show the typical decay time for Nd3+. The samples show good afterglow properties comparable with practical X-ray scintillators. The 1% and 3% Nd-doped LaMgAl11O19 samples show a good linearity in the dynamic range from 6–60,000 mGy/h. [ABSTRACT FROM AUTHOR]

The review is devoted to the analysis of the compositional disordering potential of the crystal matrix of a scintillator to improve its scintillation parameters. Technological capabilities to complicate crystal matrices both in anionic and cationic sublattices of a variety of compounds are examined. The effects of the disorder at nano-level on the landscape at the bottom of the conduction band, which is adjacent to the band gap, have been discussed. The ways to control the composition of polycationic compounds when creating precursors, the role of disorder in the anionic sublattice in alkali halide compounds, a positive role of Gd based matrices on scintillation properties, and the control of the heterovalent state of the activator by creation of disorder in silicates have been considered as well. The benefits of introducing a 3D printing method, which is prospective for the engineering and production of scintillators at the nanoscale level, have been manifested. [ABSTRACT FROM AUTHOR]

In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment's protection. However, in many cases, it is impossible to monitor ionising radiation directly at the required location continuously. This is typically either due to the lack of space to accommodate the entire dosimeter or in environments with high ionising radiation activity, electromagnetic radiation, and temperature, which significantly shorten electronics' lifetime. To allow for radiation measurement in such scenarios, we designed a fibre optic dosimeter that introduces an optical fibre link to deliver the scintillation radiation between the ionising radiation sensor and the detectors. The sensors can thus be placed in space-constrained and electronically hostile locations. We used silica optical fibres that withstand high radiation doses, high temperatures, and electromagnetic interference. We use a single photon counter and a photomultiplier to detect the transmitted scintillation radiation. We have shown that selected optical fibres, combined with different scintillation materials, are suitable for measuring gamma radiation levels in hundreds of kBq. We present the architecture of the dosimeter and its experimental characterisation with several combinations of optical fibres, detectors, and scintillation crystals. [ABSTRACT FROM AUTHOR]

The paper addresses the development of composite scintillation materials providing simultaneous real-time monitoring of different types of ionizing radiation (α-, β-particles, γ-rays) in mixed fluxes of particles and quanta. The detectors are based on composite heavy oxide scintillators consisting of a thin single-crystalline film and a bulk single-crystal substrate. The film and substrate respond to certain types of ionizing particles, forming together an all-in-one composite scintillator capable of distinguishing the type of radiation through the different time characteristics of the scintillation response. Here, we report the structure, composition, and scintillation properties under different ionizing radiations of (Lu,Gd,Tb)3(Al,Ga)5O12:Ce films deposited using liquid phase epitaxy onto Gd3(Al1−xGax)5O12:Ce (GAGG:Ce) single-crystal substrates. The most promising compositions with the highest light yields and the largest differences in scintillation decay timing under irradiation with α-, β-particles, and γ-rays were selected. Such detectors are promising for environmental security purposes, medical tomography, and other radiation detection applications. [ABSTRACT FROM AUTHOR]

Scintillators, which are widely used as radiation detectors, are phosphors that release absorbed ionizing radiation energy as ultraviolet or visible light. Inorganic glass scintillators have several advantages over inorganic crystal scintillators, such as ease of fabrication and low costs. However, unlike inorganic crystals, which can emit up to tens of thousands of photons/MeV, inorganic glasses exhibit less than several hundred photons/MeV in most cases. Here, we studied an inorganic glass scintillator that exhibits a light yield of 2700 photons/MeV, which exceeds those of previous inorganic glass scintillators with high light yields of approximately 2000 photons/MeV. The density of this material is 3.28 g/cm3, which is relatively high among glass scintillators. Moreover, a fast scintillation decay with a decay time constant of 30.0 ns was obtained and is attributed to the 5d–4f transition of Ce3+. Thus, this glass is suitable for gamma- and X-ray detection, thereby expanding the practical applicability of inorganic glass scintillators. [ABSTRACT FROM AUTHOR]

While there is great demand for effective, affordable radiation detectors in various applications, many commonly used scintillators have major drawbacks. Conventional inorganic scintillators have a fixed emission wavelength and require expensive, high-temperature synthesis; plastic scintillators, while fast, inexpensive, and robust, have low atomic numbers, limiting their X-ray stopping power. Formamidinium lead halide perovskite nanocrystals show promise as scintillators due to their high X-ray attenuation coefficient and bright luminescence. Here, we used a room-temperature, solution-growth method to produce mixed-halide FAPbX 3 (X = Cl, Br) nanocrystals with emission wavelengths that can be varied between 403 and 531 nm via adjustments to the halide ratio. The substitution of bromine for increasing amounts of chlorine resulted in violet emission with faster lifetimes, while larger proportions of bromine resulted in green emission with increased luminescence intensity. By loading FAPbBr 3 nanocrystals into a PVT-based plastic scintillator matrix, we produced 1 mm-thick nanocomposite scintillators, which have brighter luminescence than the PVT-based plastic scintillator alone. While nanocomposites such as these are often opaque due to optical scattering from aggregates of the nanoparticles, we used a surface modification technique to improve transmission through the composites. A composite of FAPbBr 3 nanocrystals encapsulated in inert PMMA produced even stronger luminescence, with intensity 3.8× greater than a comparative FAPbBr 3 /plastic scintillator composite. However, the luminescence decay time of the FAPbBr 3 /PMMA composite was more than 3× slower than that of the FAPbBr 3 /plastic scintillator composite. We also demonstrate the potential of these lead halide perovskite nanocomposite scintillators for low-cost X-ray imaging applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the Exradin W2 scintillator, PTW microDiamond, IBA Razor Nano, and IBA Razor chamber detectors for small‑field dose measurements and validate the measured data against the EGSnrc user code and observe the variation between daisy‑chained and direct measurement methods for the above detectors. Materials and Methods: The W2 scintillator, microDiamond, Razor Nano, and Razor chamber detectors were used to measure the in‑plane and cross‑plane profiles and the output factors (OFs) at 10 cm depth, and 90 source‑to‑surface distance for 6MV X‑rays (Elekta Versa HD). The field sizes ranged from 0.5 cm × 0.5 cm to 5 cm × 5 cm. The BEAMnrc/ DOSXYZnrc user codes (EGSnrc) were used to simulate the reference profiles. Gamma analysis was performed to compare the measured and simulated dose distributions. Results: The OFs measured with the W2 scintillator, microDiamond, Razor Nano chamber, Razor chamber, and the calculated Monte Carlo (MC) showed agreement to within 1% for the 3 cm × 3 cm field size. The uncertainty in the MC simulation was observed to be 0.4%. The percent difference in OFs measured using daisy‑chained and direct measurement methods was within 0.15%, 0.4%, 1.4%, and 2.4% for microDiamond, W2 scintillator, Nano, and Razor chamber detectors, respectively. Conclusion: The lateral beam profiles and OFs of W2 scintillator, microDiamond, Razor Nano, and Razor chambers exhibit good agreement with the MC simulation within the nominal field sizes. Our results demonstrate that we can achieve considerable time‑saving by directly measuring small‑field OFs without daisy‑chained methods using microDiamond and W2 scintillator. In terms of ease of use, sensitivity, reproducibility, and from a practical standpoint, we recommend microDiamond for small‑field dosimetry. [ABSTRACT FROM AUTHOR]

Scintillators, which can convert high‐energy ionizing radiation into visible light, have been serving as the core component in radiation detectors for more than a century of history. To address the increasing application demands along with the concern on nuclear security, various strategies have been proposed to develop a next‐generation scintillator with a high performance in past decades, among which the novel approach via structure control has received great interest recently due to its high feasibility and efficiency. Herein, the concept of "structure engineering" is proposed for the exploration of this type of scintillators. Via internal or external structure design with size ranging from micro size to macro size, this promising strategy cannot only improve scintillator performance, typically radiation stopping power and light yield, but also extend its functionality for specific applications such as radiation imaging and therapy, opening up a new range of material candidates. The research and development of various types of structured scintillators are reviewed. The current state‐of‐the‐art progresses on structure design, fabrication techniques, and the corresponding applications are discussed. Furthermore, an outlook focusing on the current challenges and future development is proposed. [ABSTRACT FROM AUTHOR]

The non-intrusive screening of shipping containers at national borders serves as a prominent and vital component in deterring and detecting the illicit transportation of radioactive and/or nuclear materials which could be used for malicious and highly damaging purposes. Screening systems for this purpose must be designed to efficiently detect and identify material that could be used to fabricate radiological dispersal or improvised nuclear explosive devices, while having minimal impact on the flow of cargo and also being affordable for widespread implementation. As part of current screening systems, shipping containers, offloaded from increasingly large cargo ships, are driven through radiation portal monitors comprising plastic scintillators for gamma detection and separate, typically 3He-based, neutron detectors. Such polyvinyl-toluene plastic-based scintillators enable screening systems to meet detection sensitivity standards owing to their economical manufacturing in large sizes, producing high-geometric-efficiency detectors. However, their poor energy resolution fundamentally limits the screening system to making binary "source" or "no source" decisions. To surpass the current capabilities, future generations of shipping container screening systems should be capable of rapid radionuclide identification, activity estimation and source localisation, without inhibiting container transportation. This review considers the physical properties of screening systems (including detector materials, sizes and positions) as well as the data collection and processing algorithms they employ to identify illicit radioactive or nuclear materials. The future aim is to surpass the current capabilities by developing advanced screening systems capable of characterising radioactive or nuclear materials that may be concealed within shipping containers. [ABSTRACT FROM AUTHOR]

Organic–inorganic perovskite materials with a bulk structure MAPbX3 (MA: methylamine, X: halogen) have attracted much attention in various applications such as solar cells, photodiodes, and radiation detectors. Herein, we synthesized (CH3NH3)Pb1-xMnxCl3 (or Mn-doped MAPbCl3) crystals by inverse temperature crystallization method to develop scintillator materials and evaluated their photoluminescence (PL) and scintillation properties systematically. The Mn-doped MAPbCl3 crystals showed a sharp emission peak at approximately 410–430 nm with short decay times on the order of nanoseconds and a broad peak at approximately 600 nm with a long decay time on the order of milliseconds in PL and scintillation. Furthermore, pulse height spectra of the Mn-doped MAPbCl3 crystals with a shaping time of 1 µs were measured, and the obtained scintillation light yields were estimated to be 66 (x = 1), 82 (x = 5), and 67 (x = 10) photons/5.5 MeV-α. Moreover, afterglow levels of the Mn-doped MAPbCl3 crystals were found to be 161 (x = 1), 264 (x = 5) and 170 (x = 10) ppm, which were comparable to a previously reported afterglow level of Tl-doped CsI. [ABSTRACT FROM AUTHOR]

The low-energy ultraviolet or visible photons can be produced by the interaction between the scintillator materials and ionizing radiation. For this reason, scintillator materials are widely used as radiation detectors, which are prevalently utilized in different applications such as nuclear medicine imaging, homeland security, high-energy physics, oil drilling explorations, etc. Herein, a high-atomic-number (Z) zirconium-based metal-organic framework nanoflower material CJLU-1 (Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (OH) 6 (TCA) 2 (H 2 O) 6) (H 3 TCA = tri-carboxylic acids 4,4′,4″-nitrilotribenzoic acid) was synthesized and can effectively convert X-ray into visible light. CJLU-1 is composed of secondary structural unit hexagonal Zr metal cluster and connected by TCA ligands. The photo luminescence spectra (PL) emission peak and excitation peak of CJLU-1 are at 470 nm and 395 nm respectively. CJLU-1 exhibited radioluminescence (RL) peak with a maximum at 480 nm under steady-state excitation with X-rays. Moreover, by accommodating different guest molecules such as xylene and RhB in the same MOF material, intensity-tunable X-ray scintillation can be facilely achieved, providing a new class of scintillating materials with luminescence intensity tunability. The high-Z hexagonal Zr clusters, which are arranged in an orderly fashion, absorb and interact with the ionizing radiation and sensitize the adjacent organic ligands TCA to produce efficient RL. This work contributes to the development of high-Z zirconium-based MOFs and RL intensity-tunable scintillation materials towards future practical nuclear sensing applications. A high-atomic-number (Z) zirconium-based metal-organic framework nanoflower material CJLU-1 was synthesized and can effectively convert X-ray into visible light. [Display omitted] • A zirconium-based MOF was constructed and realized tunable radioluminescence upon accommodation of guest molecules. [ABSTRACT FROM AUTHOR]

In this study, a radiation measurement system with multifunctions for the rapid radiological characterization of a decommissioned nuclear facility site was developed and evaluated. The system remotely and simultaneously measures the beta and gamma radiation from the soil at a decommissioned nuclear facility site and wirelessly transmits the measurement data to the main server, which collects and analyzes the data. The radiation-measuring part of the system is composed of a sensing probe, multichannel analyzer (MCA), and laptop computer. The sensing probe is a phoswich radiation sensor (PHORS) consisting of two inorganic scintillators (NaI(Tl) and CaF2(Eu)), each of which simultaneously measures the count rates and energies of the beta and gamma radiation. To test the performance of the PHORS, the beta and gamma radiation from a radiation source at 0–10 cm depths (at steps of 1 cm) under a soil surface was measured. The measurements show that the radiation count rates agree well with the theoretically predicted ones; the PHORS is as good as commercial radiation detectors in providing the energy spectrum of a radionuclide. In addition, a chi-square test was conducted, and the energy resolution was evaluated. The communication part of the system consisting of a global positioning system (GPS) and long-term evolution telecommunication (LTE) modem can successfully transmit the measurement data and their location information. [ABSTRACT FROM AUTHOR]

Radiation portal monitors are commonly used to detect and intercept unauthorized movement of nuclear and other radioactive materials at country borders. A total of twelve double- pillar portal monitors are present at the Greek-North Macedonian border, each containing two polystyrene scintillating detectors per pillar. Spatial and spectral response testing of the scintillating detectors to gamma radiation was performed by using different radioactive sources and comparing the measurement results with Monte Carlo simulations. A good agreement of the experimentally deduced activities of different point sources, needed for alarm triggering of the radiation portal monitors with Monte Carlo calculated values, was observed. Spectral results show no photopeaks in the spectra due to low resolution of these detectors. The broad peaks observed in the spectra correspond to the Compton edge. Measured spectra with a 137Cs source placed directly on the scintillating detector, at several positions away from the photo multiplier tube, show an energy shift of the Compton edge towards lower energies, as the source is moving away from the photo multiplier tube. The energy shift is due to light transfer mechanisms within the scintillator volume and therefore, it is only observed in optical simulations and not in gamma-ray particle simulations. [ABSTRACT FROM AUTHOR]

Scintillators belong to the oldest types of radiation detectors. Nowadays, for spectrometric purposes the use of semiconductive detectors is more common, but scintillation detectors are still in use for various specific measurement purposes. We have investigated the dependence of a gamma spectrum measured by NaI(Tl) scintillation detector on temperature changes. We examined the need of energy or efficiency recalibration and software compensation. Due to temperature dependence, scintillation detectors require energy recalibration before environmental and outdoor measurements or before the use of etalon sources for obtaining spectrum for follow-up calibration. We have elaborated on a simple method for energy recalibration of scintillation detectors at different temperatures. This method was converted into an algorithm and it can be either burned into instrument EPROM or used in software processing. [ABSTRACT FROM AUTHOR]

The purpose of this work is to analyze the use of detecting materials in radiation monitors as well as the replacement of widely used 3H-based neutron counters by neutron-detection scintillation technology. The replacement of helium counters is a consequence of two factors: the lack of 3He and widespread use of 3He-based counters in safety equipment, such as volumetric neutron detectors. Selection criteria for evaluating promising technologies are used in this work, specifically, high absolute neutron detection efficiency – efficiency at least 1.5 counts in 1 sec in detecting 1 ng 252Cf at distance of 2 m in a 20 mm thick moderator and low sensitivity to γ-ray detection – γ-ray detection efficiency not exceeding 10–6 with irradiation by a 0.1 μSv/h γ-ray source. Since they can have a large sensitive area and high resolution, scintillation detectors are now being proposed as alternatives to helium counters. But it is necessary to find an optimal scintillator possessing simultaneously low sensitivity to γ-radiation and to choose an optimal method of measuring information. Promising neutron detection technologies based on the glasses Li2OSiO2:Ce3+, LiF/ZnS(Ag+), Li6Gd(BO3)3:Ce, Cs2LiYCl6(Ce) (CLYC) as well as EJ-254 boron-doped plastic are examined from the standpoint of the posed problems. [ABSTRACT FROM AUTHOR]

Dielectric function spectra of purified thallium bromide crystals grown by the Bridgman method were studied over the photon range of 1.5–5.4 eV at room temperature. In addition, density functional theory (DFT)-based calculations of the electronic band structure were performed. Interband optical transitions associated with the obtained dielectric function were determined using standard critical point analysis. The electronic bands involved in each particular interband transition in the accessed photon energy range were identified within the calculated band structure. [ABSTRACT FROM AUTHOR]

Radiation detection characteristics of a device combining a YAP:Ce (cerium-doped yttrium aluminum perovskite) scintillator and a ZnO UV sensor were studied using X-ray radiation. Both ZnO and YAP have high resistance to radiation. A photoconductive-type UV sensor with comb-shaped Al electrodes with a gap of 50 μm was fabricated on the Zn-face of a nitrogen-doped ZnO single crystal. A photocurrent spectrum of the ZnO UV sensor showed a peak at wavelength of about 370 nm, and the sensor did not show a response in wavelengths of the visible light region. Scintillation characteristics of YAP:Ce were investigated under the condition of X-ray radiation. Scintillation luminescence of YAP:Ce showed a spectrum with a peak at a wavelength of about 360 nm, which almost corresponds to the peak wavelength of a photocurrent spectrum of the ZnO UV sensor. A device having a structure in which the YAP:Ce scintillator is placed above the ZnO UV sensor was fabricated. When the YAP:Ce scintillator was irradiated by X-rays, the photocurrent of the ZnO UV sensor was proportional to the X-ray intensity. The sensitivity of the device was improved by deposition of a reflective Al film on the YAP:Ce scintillator. The device using the combination of a YAP:Ce scintillator and a ZnO UV sensor can be used as a radiation detector with high radiation resistance. [ABSTRACT FROM AUTHOR]

Environmentally-friendly materials are being pursued world-wide for applications across a wide range of technologies. For application in spray-printed radiation detectors, water-based scintillator inks have been produced by combining a thermoplastic elastomer poly (vinyl) alcohol (PVA) and Gd 2 O 3 :Eu 3+ scintillator nanoparticles. Formulations of these green inks with different concentrations of scintillator nanoparticles have been assessed in terms of their rheological properties: the optimal concentration of scintillator nanoparticles in the water-based ink for spray-printing was 0.75 wt%. This optimized ink formulation exhibits Newtonian behavior with a viscosity around 100 cps and performance characteristics suitable for spray-printing scintillators for indirect X-ray detectors. [ABSTRACT FROM AUTHOR]

Accurate estimation of radioactivity content of various samples and effluents is essential in all stages of operation at a nuclear facility. Generally, two separate systems are used for estimation of α and gross β activity. A single counting setup with a detector probe consisting of a combination of ZnS (Ag) and plastic scintillator detectors can be applied for this purpose. This paper describes design, development, and characterization of a combination detector system for simultaneous assessment of α and β/γ radioactivity content of an electrodeposited or planchetted sample or that of a filter paper. Pulse height discrimination technique has been utilized to distinguish between α and β radiations. The β activity counts had been observed to contribute <0.7% in α activity. Counts from α activity are added up in β channel counts, and it was observed that for 239Pu source, it is about 2.5 times. Efficiency of the system for β sources was found to have varied from about 14% (137Cs) to 23% (90Sr/90Y). The efficiency for 238Pu α source was found to be 13.4%. [ABSTRACT FROM AUTHOR]

A scoping study of a commercially available resin selective for aqueous plutonium (Pu), AnaLig® Pu-02, modified with scintillator was investigated as a scheme to simultaneously concentrate and detect Pu in aquatic matrices. The extractive scintillating resin was comprised of a silica base, functionalized for plutonium extraction, grafted with plastic scintillator of polyvinyl toluene (PVT) and 2-(1-naphthyl)-4-vinyl-5- phenyloxazole (vNPO) fluor. Scintillator was incorporated onto the AnaLig® Pu-02 resin in a two-step process of silanization followed by surface-polymerization. Successful modification was facilitated by grinding the resin beads prior to silanization to expose cleaved silica surface sites appropriate for scintillator grafting. The modified resin was subjected to initial characterization of batch uptake and radioluminosity measurements where a total detection efficiency of 32.5% was observed. The modified resin was then subjected to pH 1 simulants containing environmental relevant groundwater constituents of varying concentration. Concentrations of 0.001M Fe(III) interfered with Pu uptake, while concentrations of up to 0.01M Ca(II) and 0.001 mM concentration of natural uranium and thorium had minimal influence on plutonium uptake. A translucent column packed with the modified AnaLig® Pu-02 was placed in a commercial flow-cell radiation detector for real-time detection of plutonium; a total detection efficiency of 20.4% was achieved for on-line measurements. The modification of AnaLig® Pu-02 results in a minimum detection limit capable of meeting the EPA limit for gross alpha activity in drinking water given a sufficient counting time of 15 min and approximately 300 mL of solution volume. • Scintillation functionality added to a commercially available resin. • Demonstrated sensitive off-line and on-line quantification of aqueous plutonium. • Demonstrated selective uptake of Pu(IV/V) over Fe(III) and other common ions. [ABSTRACT FROM AUTHOR]

In this paper, we develop a novel energy-resolved X-ray detector based on the CuIn 1-x Ga x Se 2 (CIGS) photoelectric conversion layer. The effect of Ga content on the crystal phase and the dark current of the photoelectric conversion layer has been studied. Furthermore, the photoelectric conversion capability of the CIGS thin film layer is optimized by the surface passivation process including the sulfurization treatment and Al 2 O 3 treatment, achieving a low dark current of 90 nA/cm2 and high specific detectivity of 2.3 × 1014 Jones. The optimized CIGS photoelectric conversion layer and the Gd 2 O 2 S scintillator are used in the X-ray detector. The directions of the incident X-ray propagation and the induced fluorescence signal propagation are mutually perpendicular, thus the effective thickness of the scintillator is substantially increased without sacrificing the resolution of the sensor. In addition, the X-ray response of the detector is evaluated, the pixels at different X-ray penetration depths show obvious differences in absorption, contributing its ability of energy-resolution. The sensitivity of the prepared indirect X-ray detector is ∼8 μCGy air −1cm2 at an irradiation intensity of ∼6.5 mGy air /s. This work offers a new strategy to fabricate high performance energy-resolved X-ray detectors. [Display omitted] • An energy-resolved X-ray detector is first constructed with CIGS absorption layer. • The CIGS photodetector shows a low dark current of 90 nA/cm2. • High specific detectivity of 2.3 × 1014 Jones performed for the CIGS photodetector. • The X-ray detector has ∼8 μCGyair−1cm2 at a ∼6.5 mGyair/s irradiation intensity. • The CIGS photodetector realizes low radiation dose without sacrificing resolution. [ABSTRACT FROM AUTHOR]

For the first time a molecule of 2-(4-styrylphenyl)benzoxazole containing benzoxazole and stilbene groups is applied as a scintillator dopant acting as a wavelength shifter. In this article a light yield of the plastic scintillator, prepared from styrene doped with 2 wt% of 2,5-diphenylbenzoxazole and 0.03 wt% of 2-(4-styrylphenyl)benzoxazole, is determined to be as large as 60%±2% of the anthracene light output. There is a potential to improve this value in the future by the optimization of the additives concentrations. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop and evaluate fiber-optic sensors for the remote detection of gamma rays in areas that are difficult to access, such as a spent fuel pool. The fiber-optic sensor consists of a light-generating probe, such as scintillators for radiation detection, plastic optical fibers, and light-measuring devices, such as PMT. The (Lu,Y)2 SiO5:Ce(LYSO:Ce) scintillator was chosen as the light-generating probe. The (Lu,Y)2 SiO5:Ce(LYSO:Ce) scintillator has higher scintillation efficiency than the others and transmits light well through an optical fiber because its refraction index is similar to the refractive index of the optical fiber. The fiber-optic radiation sensor using the (Lu,Y)2 SiO5:Ce(LYSO:Ce) scintillator was evaluated in terms of the detection efficiency and reproducibility for examining its applicability as a radiation sensor. [ABSTRACT FROM AUTHOR]

This manuscript summarizes recent results on the development of composite luminescent materials based on the single-crystalline films and single crystals of simple and mixed garnet compounds obtained by the liquid-phase epitaxy growth method. Such composite materials can be applied as scintillating and thermoluminescent (TL) detectors for radiation monitoring of mixed ionization fluxes, as well as scintillation screens in the microimaging techniques. The film and crystal parts of composite detectors were fabricated from efficient scintillation/TL materials based on Ce3+-, Pr3+-, and Sc3+-doped Lu3Al5O12 garnets, as well as Ce3+-doped Gd3−xAxAl5−yGayO12 mixed garnets, where A = Lu or Tb; x = 0–1; y = 2–3 with significantly different scintillation decay or positions of the main peaks in their TL glow curves. This work also summarizes the results of optical study of films, crystals, and epitaxial structures of these garnet compounds using absorption, cathodoluminescence, and photoluminescence. The scintillation and TL properties of the developed materials under α- and β-particles and γ-quanta excitations were studied as well. The most efficient variants of the composite scintillation and TL detectors for monitoring of composition of mixed beams of ionizing radiation were selected based on the results of this complex study. [ABSTRACT FROM AUTHOR]

In the anisotropic scintillators the light output and the pulse shape for heavy particles ( p, α, nuclear recoils) depend on the direction with respect to the crystal axes; the response to γ/ β radiation is isotropic instead. This feature offers the possibility to study the directionality approach, which is applicable in the particular case of those Dark Matter candidate particles inducing just nuclear recoils. Among the anisotropic scintillators, the ZnWO has unique features, which make it an excellent candidate for this type of research, and there is still plenty of room for the improvement of its performances. In this paper the possibility of a low background pioneer experiment (named ADAMO-Anisotropic detectors for DArk Matter Observation) to exploit deep underground the directionality approach by using anisotropic ZnWO scintillators is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Anew type high spatial resolution radiation detector based on UV scintillators + UV imaginggas photomultiplier is presented. The prototype UV detector consists of a 10cm×10cm μPIC,2GEMs,aUV transparent windowandaCsI photocathode deposited on the window or the surface of the upper GEM. The effective photo-sensitive area is ø34mm andthe readouts are 400um-pitch strips.Anewlydeveloped LuLiF4(Nd) crystal which emits 183nm photonsis directly coupled to the detector as the window. The detector was tested in pulse mode operation with 5.5MeV α particles from 241Am and 122keV γ rays from 57Co. The window images were clearly obtained and the position resolution of o(mm) is confirmed. [Copyright &y& Elsevier]

Abstract: SuperB is a super-flavor factory that will be built in Tor Vergata (Italy). The project, recently approved by the Italian Government, and classified as the flagship project of the Italian INFN, foresees the construction of a high intensity asymmetric electron-positron collider and of the related detector. The expected luminosity of 2x1036cm−2 s−1, a factor 100 higher than the last generation of B-factories, will allow the high statistic study of rare decays and, possibly, will allow a deeper insight in the field of new physics. Part of the SuperB apparatus is the Instrumented Flux Return (IFR). This detector exploits the flux return iron structure of the superconducting solenoid as absorber for the identification of muons and neutral hadrons. In more details, It consists of ≃ 92 cm of iron interleaved by 9 layers of highly segmented scintillators. The detection technique is based on relatively inexpensive extruded plastic scintillator bars produced at the FNAL-NICADD facility. The scintillation light is collected through Wave Length Shifting fibers and guided to recently developed devices called Silicon Photon Multipliers used as photodetectors. The use of plastic scintillator as active material ensures reliability, robustness and long term stability while the high granularity and the fast response guarantee a good space-time resolution, extremely important to cope with the expected high particles flux. The readout scheme under evaluation is this manuscript is the double coordinate readout (“BIRO readout”) where two layers of orthogonal scintillator bars provide both, the polar and azimuthal coordinate. In order to deeply understand the performances and possible drawbacks of the above technique, a full depth prototype has been designed and built in Ferrara and Padova, and tested at the Fermilab Test Beam Facility (FBTF) in December 2010. In this paper a comprehensive description of the IFR related R&D studies will be presented. In particular, we will focus on the results of the Fermilab beam test, issues and future activities will also be outlined. [Copyright &y& Elsevier]

Abstract: Extruded scintillator with wavelength shifting (wls) fiber for light collection and silicon avalanche photo-detection (SiPM), followed by modest amplification remains an attractive candidate for large area counters such as are required for muon detectors/tail catchers for collider detectors. We report on R & D for the optimization of such detectors which has included the development of ad hoc SiPMs and frontend electronics with 12 bit waveform digitization at 100 – 200MHz. Bias voltage is generated locally and provision is made for on board data storage and fast transfer to a local PC for immediate analysis. In addition to describing the data collection and counter assembly we will present representative data results from tests performed at the Fermilab Test Beam Facility. [Copyright &y& Elsevier]

Abstract: Knowledge of prompt fission γ-ray emission has been of major interest in reactor physics for a few years. Since very few experimental spectra were ever published until now, new measurements would be also valuable to improve our understanding of the fission process. An experimental method is currently being developed to measure the prompt fission γ-ray spectrum from some tens keV up to 10 MeV at least. The mean multiplicity and total energy could be deduced. In this method, the γ-rays are measured with a bismuth germanate (BGO) detector which has the advantage to present a high P/T ratio and a high efficiency compared to other γ-ray detectors. The prompt fission neutrons are rejected by the time of flight technique between the BGO detector and a fission trigger given by a fission chamber or a scintillating active target. Energy and efficiency calibration of the BGO detector were carried out up to 10.76 MeV by means of the 27Al(p,γ) reaction. First prompt fission γ-ray spectrum measurements performed for the spontaneous fission of 252Cf and for 1.7 and 15.6 MeV neutron-induced fission of 238U at the CEA, DAM, DIF Van de Graaff accelerator, will be presented. [Copyright &y& Elsevier]

Radiation detectors, employed in X-ray medical imaging, consist of a scintillating (fluorescent) screen emitting visible light coupled to optical sensors. Screens are fabricated by specially developed scintillators (phosphors). Up to now scintillation screens were prepared by sedimentation on fused silica substrate (spectrosil B) in a form of transparent disk 30mm in diameter and 3mm in thickness. A new sedimentation method is proposed by deposition of scintillation powders on rectangular Borosilicate glass substrate 22x22 mm² with thicknesses of 0.13-0.17 mm (Waldemar Knittel-GmbH). The optical properties of the substrate were examined in terms of light absorption and transmission in the range between 200-800nm (visible range) and found adequate for use with the common scintillation powders (transmissivity 95%). New screens of various coating thicknesses were examined under medical X-ray irradiation, placed in direct contact with a CMOS (RadEye) optical detector. X-ray images of a test object demonstrate the fine quality and spatial resolution of the above screens. Due to the rectangular shape of the substrate images taken from the prepared screens are indicative for their potential use in the X-ray digital medical systems. [ABSTRACT FROM AUTHOR]