Search Results (58)

The search for new bright scintillators with performance close to ideal is the target for many research centers worldwide. This paper presents advanced bright thallium (Tl)-based K₂PtCl₆-type intrinsic scintillators for detection and imaging applications. Dopant-free Tl-based compounds of Tl₂HfX₆ and Tl₂ZrX₆ (X = Cl, Br, or mixed halogens) that were investigated, grown, and published previously are now scaled up to one-inch-diameter crystals. Energy resolutions of 4.1% for Tl₂HfCl₆, 4.4% for Tl₂ZrCl₆, 4.8% for Tl₂Hf(Cl,Br)₆, and 4.1% for Tl₂Zr(Cl,Br)₆, as well as light yields of 22,300 ph/MeV for Tl₂HfCl₆, 38,500 ph/MeV for Tl₂ZrCl₆, 19,000 ph/MeV for Tl₂Hf(Cl,Br)₆, and 39,900 ph/MeV for Tl₂Zr(Cl,Br)₆, are measured. These crystals have generally linear responses to gamma-rays above 100 keV. Because of their many favorable attributes, these novel crystals will be beneficial in many gamma-ray detector applications that require better physical densities, Z_eff values, energy resolutions, and relative detection efficiency than NaI:Tl, without the constraints of light yield and decay time constants. Full article

Achieving reliable, grid-scale electricity generation from nuclear fusion, as envisioned by the DEMOnstration Fusion Power Plant (DEMO) and future commercial reactors, requires unprecedented plasma stability and long-term control. This operational goal is fundamentally challenged by, among others, the dynamic nature of the high temperature plasma and the need to monitor high-Z impurities, such as tungsten, which can severely compromise energy confinement, resulting in discharge disruption and damage to internal reactor walls. Real-time Soft X-ray (SXR) diagnostic systems are therefore an integral and critical component of fusion power plant infrastructure, providing essential temporal and spatial resolution data on these fast-evolving phenomena. To address the severe demands imposed by the extreme operating environment of future fusion reactors, such as DEMO (including intense neutron and gamma fluxes), this work details a current stage in the long-term development of an advanced and robust diagnostic system engineered specifically for technological preparation and future application in these high-fluence environments. This paper presents the third generation of the SXR measurement system, GEM3k, based on Gas Electron Multiplier (GEM) technology. This novel diagnostic utilizes a Field Programmable Gate Array (FPGA)-based architecture, specifically designed for the high-rate acquisition of energy- and spatially resolved plasma radiation distributions. The GEM3k design exploits the inherent radiation hardness of GEM detectors, positioning them as robust sensor units for monitoring plasma dynamics and impurity emissions in future fusion environments. The system readout comprises approximately 34,000 individual pixels mapped to nearly 3000 measurement channels in an XYUV coordinate configuration. This layout enables submillimeter spatial resolution simultaneously with a time resolution better than 10 ms. Addressing the engineering challenges of such a complex high-density readout, this work details the comprehensive design of the GEM3k system, focusing on its architecture, electronics, performance estimations, and data distribution strategies. By enabling precise tracking of impurities and fast plasma behavior, the GEM3k system contributes to the stable, high-gain operation required for future fusion reactors. This directly supports the development of sustainable fusion energy and its eventual integration into modern electricity grids. Furthermore, the planned enhancement to a real-time operating mode could pave a way for a next-generation system for direct integration into reactor control loops. Currently in the prototype phase with initial hardware tests completed, the GEM3k design leverages our extensive experience with diagnostics developed for the JET and WEST tokamaks. Full article

This paper presents the procedures employed for experimental functional and performance characterization of a 2 × 2 pixel prototype detection system tailored specifically for the X and Gamma-ray Imaging Spectrometer (XGIS) instrument onboard the THESEUS mission. The XGIS system comprises of two coded masked wide field cameras integrated with monolithic SDDs (Silicon Drift Detectors) and CsI:Tl (Thallium doped-Cesium Iodide) scintillators, contributing to its broad X and $\gamma$-ray detection range. Given the space instrumentation complexity, thorough requirement qualification and testing procedures are essential. This work focuses on working principle, the testing setup utilized, and observed performance for the small scale four-pixel XGIS prototype. Furthermore, the alignment of light output performance of the four-pixel SDD and scintillator prototype detection system with the XGIS instrument requirements is emphasized. Full article

The increasing demand for sustainable and multifunctional materials in radiation shielding and optical applications has driven research toward utilizing natural and waste-derived reinforcements in polymer matrices. However, achieving effective attenuation performance across different radiation types using eco-friendly fillers remains a significant challenge. In this study, polyvinyl chloride (PVC)/Polystyrene (PSt) blend composites (1:1 weight ratio) were reinforced with powdered snail shell (SSP) as a biogenic additive, aiming to enhance their shielding and optical performance. Composites containing 5%, 10%, 20%, and 30% SSP (w/v) were fabricated and characterized. Key parameters including linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), mean free path (MFP), half-value layer (HVL), and effective atomic number (Zeff) were measured using a variable-energy X-ray source (13.37–59.54 keV) and ULEGe detector. Fast neutron shielding performance and theoretical values for build-up factor (EBF) and macroscopic neutron cross-sections were also calculated. The results showed a marked improvement in X-ray attenuation with increasing SSP content (SSP30 > SSP20 > SSP10 > SSP5), while neutron shielding declined due to the high oxygen content of SSP. Among the tested samples, the SSP30 composite exhibited the highest X-ray attenuation efficiency, whereas the SSP5 composition showed the greatest enhancement in optical reflectance and neutron absorption, indicating optimal performance in these respective tests. Additionally, 5% SSP incorporation improved optical reflectance by 12%, indicating enhanced photon backscattering at the material surface. This behavior contributes to improved gamma shielding efficiency by reducing photon penetration and enhancing surface-level attenuation. These findings highlight the potential of snail shell-based fillers as low-cost, sustainable reinforcements in multifunctional polymer composites. Full article

The X and Gamma Imager and Spectrometer (XGIS) on board THESEUS is a finely pixelized and modular instrument designed for broadband high-energy transient detection. XGIS consists of two cameras, each composed of 10 supermodules, with each supermodule further divided into 10 modules and each module made with 64 independent readout pixels based on Silicon Drift Detectors coupled with 5 × 5 × 30 mm³ CsI scintillator bars. An algorithm to quickly read out the signals from the 64 pixels and send them in chronological order through the module and supermodule logic up to the camera logic is under development. Furthermore, a challenge for space-based high-energy instruments is distinguishing X-/gamma-ray photons while effectively rejecting background photons and particles, including electrons, protons, and heavier cosmic rays. Unlike traditional systems that rely on anticoincidence systems, XGIS aims to achieve background rejection through an innovative readout logic that analyzes the spatial and temporal properties of energy deposits in the detector. By leveraging the finely pixelized structure, the readout system can differentiate single-photon events from charged-particle tracks based on energy deposition patterns and event topology. Full article

X-ray response performances of a p-NiO/β-Ga₂O₃ hetero-junction diode (HJD) X-ray detector were studied before and after γ-ray irradiation at −200 V, with a total dose of 13.5 kGy(Si). The response performances of the HJD X-ray detector were influenced by the trap-assistant conductive process of the HJD under reverse bias, which exhibited an increasing net (response) current, nonlinearity, and a long response time. After irradiation, the Poole–Frenkel emission (PFE) dominated the leakage current of HJDs due to the higher electric field caused by the increased net carrier concentration of β-Ga₂O₃. This conductive process weakened the performance of the HJD X-ray detector in terms of sensitivity, output linearity, and response speed. This study provided valuable insights into the radiation damage and performance degradation mechanisms of Ga₂O₃-based radiation detectors and offered guidance on improving the reliability and stability of these radiation detectors. Full article

This review explores the applications of room temperature semiconductor detectors, with a focus on Cd(Zn)Te based detection systems, in non-destructive testing and evaluation (NDT&E). Cd(Zn)Te detectors, which operate efficiently at ambient temperatures, eliminate the need for cryogenic cooling systems and offer high energy and spatial resolution, making them ideal for a wide range of NDT&E applications. Key performance parameters such as energy resolution, spatial resolution, time resolution, detector efficiency, and form factor are discussed. The paper highlights the utilization of Cd(Zn)Te detectors in various imaging and spectroscopic applications, including nuclear threat detection and non-proliferation, archaeological NDT, and Unmanned Aerial Vehicle radiological surveying. Cd(Zn)Te detectors hold significant promise in NDT&E due to their high-resolution imaging, superior spectroscopic capabilities, versatility, and portability. Full article

Low-density foreign objects (LDFOs) in foods pose significant safety risks to consumers. Existing detection methods, such as metal and X-ray detectors, have limitations in identifying low-density and nonmetallic contaminants. To address these challenges, our research group constructed and optimized a continuous-wave sub-terahertz (THz) imaging system for the real-time, on-site detection of LDFOs in infant snacks. The system was optimized by adjusting the attenuation value from 0 to 9 dB and image processing parameters [White (W), Black (B), and Gamma (G)] from 0 to 100. Its detectability was evaluated across eight LDFOs underneath snacks with scanning at 30 cm/s. The optimal settings for puffed snacks and freeze-dried chips were found to be 3 dB attenuation with W, B, and G values of 100, 50, and 80, respectively, while others required 0 dB attenuation with W, B, and G set to 100, 0, and 100, respectively. Additionally, the moisture content of infant snacks was measured using a modified AOAC-based drying method at 105 °C, ensuring the removal of all free moisture. Using these optimized settings, the system successfully detected a housefly and a cockroach underneath puffed snacks and freeze-dried chips. It also detected LDFOs as small as 3 mm in size in a single layer of snacks, including polyurethane, polyvinyl chloride, ethylene–propylene–diene–monomer, and silicone, while in two layers of infant snacks, they were detected up to 7.5 mm. The constructed system can rapidly and effectively detect LDFOs in foods, offering a promising approach to enhance safety in the food industry. Full article

Ultra-high-energy cosmic rays (UHECRs) are extremely rare energetic particles of ordinary matter in the Universe, traveling astronomical distances before reaching the Earth’s atmosphere. When primary cosmic rays interact with atmospheric nuclei, cascading extensive air showers (EASs) of secondary elementary particles are developed. Radio detectors have proven to be a reliable method for reconstructing the properties of EASs, such as the shower’s axis, its energy, and its maximum (${\mathrm{X}}_{\max }$). This aids in understanding fundamental astrophysical phenomena, like active galactic nuclei and gamma-ray bursts. Concurrently, data science has become indispensable in UHECR research. By applying statistical, computational, and deep learning methods to both real-world and simulated radio data, researchers can extract insights and make predictions. We introduce a convolutional neural network (CNN) architecture designed to classify simulated air shower events as either being generated by protons or by iron nuclei. The classification achieved a stable test error of 10%, with Accuracy and ${\mathrm{F}}_1$ scores of 0.9 and an MCC of 0.8. These metrics indicate strong prediction capability for UHECR’s nuclear composition, based on data that can be gathered by detectors at the world’s largest cosmic rays experiment on Earth, the Pierre Auger Observatory, which includes radio antennas, water Cherenkov detectors, and fluorescence telescopes. Full article

The detection of Gamma-Ray Bursts (GRBs) using spaceborne X/gamma-ray photon detectors depends on a reliable background count rate estimate. This study focuses on evaluating a data-driven background estimator based on a neural network designed to adapt to various X/gamma-ray space telescopes. Three trials were conducted to assess the effectiveness and limitations of the proposed estimator. Firstly, quantile regression was employed to obtain an estimation with a confidence range prediction. Secondly, we assessed the performance of the neural network, emphasizing that a dataset of four months is sufficient for training. We tested its adaptability across various temporal contexts, identified its limitations and recommended re-training for each specific period. Thirdly, utilizing Explainable Artificial Intelligence (XAI) techniques, we delved into the neural network output, determining distinctions between a network trained during solar maxima and one trained during solar minima. This entails conducting a thorough analysis of the neural network behavior under varying solar conditions. Full article

This study explores the suitability of (Cd,Mn)Te and (Cd,Mn)(Te,Se) as room-temperature X-ray and gamma-ray detector materials, grown using the Bridgman method. The investigation compares their crystal structure, mechanical and optical properties, and radiation detection capabilities. Both crystals can yield large-area single crystal samples measuring approximately 30 × 30 mm². In low-temperature photoluminescence analysis, both materials showed defect states, and annealing in cadmium vapors effectively eliminated donor–acceptor pair luminescence in (Cd,Mn)Te but not in (Cd,Mn)(Te,Se). Moreover, harder (Cd,Mn)(Te,Se) exhibited a higher etch pit density compared to softer (Cd,Mn)Te. X-ray diffraction examination revealed uniform lattice constant distribution in both compounds, with variations at a part per million level. (Cd,Mn)Te crystals demonstrated excellent single crystal properties with narrower omega scan widths, while (Cd,Mn)(Te,Se) exhibited a high contribution of block-like structures with significantly larger misorientation angles. Spectroscopic evaluations revealed better performance of a pixelated (Cd,Mn)Te detector, in comparison to (Cd,Mn)(Te,Se), achieving a mean full width at half maximum of 14% for the 122 keV gamma peak of Co-57. The reduced performance of the (Cd,Mn)(Te,Se) detector may be attributed to deep trap-related luminescence or block-like structures with larger misorientation angles. In conclusion, Bridgman-grown (Cd,Mn)Te emerges as a more promising material for X-ray and gamma-ray detectors when compared to (Cd,Mn)(Te,Se). Full article

In recent years, rare earth silicate compounds have attracted the extensive attention of researchers owing to their potential for applications in scintillation crystals in gamma ray or X-ray detectors, as well as in thermal or environmental barrier coatings. Large high quality crystals of three members of the rare earth monosilicates family of compounds, $R_2{\mathrm{SiO}}_5$ (with R = Dy, Ho, and Er), have been grown by the floating zone method, using a laser-diode-heated floating zone furnace. Crystal growths attempts were carried out using different parameters in order to determine the optimum conditions for the growth of these materials. The phase purity and the crystalline quality of the crystal boules were analysed using powder and Laue X-ray diffraction. Single crystal X-ray diffraction experiments were carried out to determine the crystal structures of the boules. The optimum conditions used for the crystal growth of $R_2{\mathrm{SiO}}_5$ materials are reported. The phase purity and high crystalline quality of the crystals produced makes them ideal for detailed investigations of the intrinsic physical and chemical properties of these materials. Full article

LaBr${}_3$:Ce crystals have good scintillation properties for X-ray spectroscopy. Initially, they were introduced for radiation imaging in medical physics with either a photomultiplier or SiPM readout, and they found extensive applications in homeland security and gamma-ray astronomy. We used 1${}^{″}$ round LaBr${}_3$:Ce crystals to realize compact detectors with the SiPM array readout. The aim was a good energy resolution and a fast time response to detect low-energy X-rays around 100 keV. A natural application was found inside the FAMU experiment, at RIKEN RAL. Its aim is a precise measurement of the proton Zemach radius with impinging muons, to contribute to the solution to the so-called “proton radius puzzle”. Signals to be detected are characteristic X-rays around 130 KeV. A limit for this type of detector, as compared to the ones with a photomultiplier readout, is its poorer timing characteristics due to the large capacity of the SiPM arrays used. In particular, long signal falltimes are a problem in experiments such as FAMU, where a “prompt” background component must be separated from a “delayed” one (after 600 ns) in the signal X-rays to be detected. Dedicated studies were pursued to improve the timing characteristics of the used detectors, starting from hybrid ganging of SiPM cells; then developing a suitable zero pole circuit with a parallel ganging, where an increased overvoltage for the SiPM array was used to compensate for the signal decrease; and finally designing ad hoc electronics to split the 1${}^{″}$ detector’s SiPM array into four quadrants, thus reducing the involved capacitances. The aim was to improve the detectors’ timing characteristics, especially falltime, while keeping a good FWHM energy resolution for low-energy X-ray detection. Full article

We present an innovative X-ray spectroscopy system to address the complex study of the X-ray emissions arising from laser–target interactions, where the emissions occur within extremely brief intervals from femtoseconds to nanoseconds. Our system combines a Gas Electron Multiplier (GEM) detector with a silicon-based Timepix3 (TPX3) detector. These detectors work in tandem, allowing for a spectroscopic radiation analysis along the same line of sight. With an active area of 10 × 10 cm${}^2$, the GEM detector allows for 1D measurements for X-ray energies (2–50 keV) by utilizing the full 10 cm gas depth. The high-energy part of the radiation beam exits through a downstream side window of the GEM without being absorbed in the gas volume. Positioned side-on at the GEM detector’s exit, the TPX3 detector, equipped with a pixelated sensor (55 µm × 55 µm; active area 14 mm × 14 mm), uses its full 14 mm silicon sensor to detect hard X-rays (50–500 keV) and gamma rays (0.5–10 MeV). We demonstrate the correct operation of the entire detection system and provide a detailed description of the Timepix3 detector’s calibration procedure, highlighting the suitability of the combined system to work in laser plasma facilities. Full article

Since bentonite can absorb neutrons and gamma rays without sacrificing structural integrity, it is frequently used as the main shielding material in many nuclear installations. Recently, there has been a trend toward enhancing the shielding qualities of bentonite by adding various chemicals. However, the majority of the added materials either require particular handling procedures or pose health risks. The availability of environmentally friendly additives would be wonderful. The addition of barite to bentonite composites greatly raises the density of the specimens. Additionally, the performance of bentonite–barite composites as radiation shielding materials is improved by adding various amounts of bulk and nano Bi₂O₃ as a filler (6%, 13%, and 20%). Energy dispersive X-ray analysis (EDX) was used to determine the chemical makeup of the produced specimens. The scanning electron microscopy (SEM) pictures showed the samples’ cross-sections’ porosity and homogeneity. ²⁴¹Am, ¹³³Ba, ¹³⁷Cs, and ⁶⁰Co are radioactive sources that emit energies of 59.53, 80.99, 356.01, 661.66, 1173.23, and 1332.5 keV, respectively, and the NaI (Tl) scintillation detector was used in this investigation. The area under the peak of the observed energy spectra was measured using the Genie 2000 program in both the specimen’s absence and presence. The coefficients for linear and mass attenuation were calculated. To determine the theoretical mass attenuation coefficients, the XCOM program was utilized and then compared to the corresponding experimental values. Various radiation shielding parameters dependent on the linear attenuation coefficient were computed for each studied composite. These parameters include the mean free path (MFP), half value layer (HVL), and tenth value layer (TVL). Also, the Z_eff and the EABF were determined for each specimen. According to the findings, bismuth oxide was added to bentonite–barite composites to reduce the transmitted flux through the specimens, which increased the LAC of the bentonite–barite composites. Furthermore, adding nanosized bismuth oxide particles increased the sample’s density and improved the material’s shielding properties. At a photon energy of 0.356 keV, the relative deviation (∆%) between the experimental nano- and micro values for Bi₂O₃ (20 wt%) was 12.1974, confirming that the nanoparticles increase attenuation efficiency. Full article