Radiation Detectors Research Articles

Determination of the type of radioactive nuclei and gamma spectrometry analysis for radioactive sources

Determining the type of radioactive nuclei is the second activity after the inventory of radioactive waste in Kosovo, their location and the number of radioactive sources. Before starting any type of radioactive waste action, it is necessary to determine the content of their activity, the type of radioisotope, physical and chemical form and the risks associated with their management. The realization of this is achieved as a combination of quality assurance processes, the inventory of the radioisotope and its activity that is present in the waste, the composition of the waste material and direct measurements. This serious activity was carried out entirely in the field and was undertaken due to the lack of source certification or any other indication of their classification and activity. The process of determining the type of radioactive nuclei helps to realize a more effective characterization of them as well as to determine the path of waste management. The probability that a gamma radiation detector interacts with it to produce a pulse represents the effectiveness of the detector.

Evaluation of High-Resolution Radiation Detectors in Small Field Radiation Measurements

Evaluation of High-Resolution Radiation Detectors in Small Field Radiation Measurements

Probing the optical properties and toxicological profile of zinc tungstate nanorods.

Zinc tungstate is a semiconductor known for its favorable photocatalytic, photoluminescence, and scintillation properties, coupled with its relatively low cost, reduced toxicity, and high stability in biological and catalytic environments. In particular, zinc tungstate evinces scintillation properties, namely the ability to emit visible light upon absorption of energetic radiation such as x rays, which has led to applications not only as radiation detectors but also for biomedical applications involving the delivery of optical light to deep tissue, such as photodynamic therapy and optogenetics. Here, we report on the synthesis of zinc tungstate nanorods generated via an optimized but facile method, which allows for synthetic control over the aspect ratio of the as-synthesized anisotropic motifs via rational variation of the solution pH. We investigate the effect of aspect ratio on their resulting photoluminescent and radioluminescent properties. We further demonstrate the potential of these zinc tungstate nanorods for biomedical applications, such as photodynamic therapy for cancer treatment, by analyzing their toxicological profile within cell lines and neurons.

Mega-electron volt proton detection using a thin diamond membrane detector

The development of single crystal chemical vapour deposition (scCVD) diamond membrane radiation detector is introduced in this paper. The fabrication of the diamond membrane radiation detector is illustrated, including the improvement of the diamond membrane sample and the usage of a homemade printed circuit board (PCB) to reduce the influence of the external noise and to build a complete device in a small volume. From the experimental results, the behavior of the diamond radiation detector using a beam of 2 MeV protons indicates that a 6.1 μm Optical-grade diamond membrane is capable of detecting the transmitted protons with low energy loss. The experimental results are fitted using the modified Hecht equation to introduce the avalanche effect.

Temperature-Dependent Photoluminescence from Well-Resolved Excited State Structures in Rare-Earth-Based Double Perovskites.

Lead-free halide double perovskites (DPs) have become a research hotspot in the field of photoelectrons due to their unique optical properties and flexible compositional tuning. However, the reports on the optical properties of DPs primarily concentrate on the room temperature state and only exhibit single emission band. Here, we synthesized Cs2NaYCl6:Sb3+, Dy3+ DPs by a solvothermal method to realize white light emission with photoluminescence (PL) quantum yield as high as 70.7%. The energy-transfer process from self-trapped excitons (STEs) to Dy3+ ions was revealed by optical characterization and theoretical simulation calculations. Interestingly, we observed the double-emission from low-energy STE emission of Sb3+ ions and Dy3+ emission at low temperatures, and the double-emission is consistent with the asymmetric doublet feature of the 3P1 → 1S0 transition split into two minima. The PL spectra further showed that the fluorescence intensity ratios of Dy3+ ions at 580 and 680 nm were strongly temperature-dependent, and the relative sensitivity is up to 1.79% K-1 at 360 K. Moreover, the near-infrared and radiation luminescence properties indicated that the Cs2NaYCl6:Sb3+, Dy3+ DPs also have good prospects for night vision and radiation detection, as well as the great potential for applications in solid-state illumination and optical temperature measurement.

Computational investigation of transport parameters of ions in gas-filled radiation detectors

In this study, a novel computational method was developed to investigate the transport characteristics of ions in gas-filled radiation detectors, which are closely linked to the behavior of ions in gaseous detectors. Parameters such as polarizability, mean free path, collision frequency, and mean free time, which directly impact ion mobility, were physically manipulated using the Monte Carlo technique, and the results were validated against fundamental physical principles. As an initial scenario, computations were performed on the mobility of Ar+ ions in an argon environment as a carrier gas. The distribution of the radial velocity components of the ion following an ion-gas collision was represented as a two-dimensional histogram with a disc-shaped pattern, and this result was elucidated utilizing the Maxwell-Boltzmann distribution. The findings regarding the mean free time and mean free path of an Ar+ ion in an argon carrier gas align with the results derived from Skullerud's methodologies. These findings hold promise for Garfield++ simulations, enabling the computation of ion mobility and even cluster ions in the mixture, thereby considering their impact on the detector's gain parameters. The results of this investigation offer novel insights into the behavior of ions within detector settings, significantly enhancing our comprehension of the mobility of ions and its effects on radiation detection efficiency.

Distributed Optical Fiber-Based Radiation Detection Using an Ultra-Low-Loss Optical Fiber

The combination of an ultra-low-loss optical fiber sensitive to ionizing radiation and an optical time domain reflectometer (OTDR) is investigated to explore the feasibility of a single-ended distributed radiation detector. The peculiarity of the tested fiber resides in its regenerative high radiation-induced attenuation (RIA) response in the infrared spectrum (1310 nm), which returns to a low value once the irradiation has ended, combined to its sensitivity, highly increasing with the dose rate. In this work, only some sections of the fiber line were irradiated with 100 kV X-rays at room temperature, to prove the spatially resolved radiation detection capabilities of the system. The transient RIA response of the fiber was characterized at different pre-irradiation doses. A pre-irradiation treatment was shown to stabilize the optical fiber response, improving its RIA vs. dose rate linearity and repeatability. This improved response, in terms of radiation quantification, comes at the cost of a lower detection threshold. This work lays the bases for a distributed radiation detector, with some capabilities in dose rate evaluation.

GPU Optimization Techniques to accelerate optiGAN - a particle simulation GAN

Abstract The demand for specialized hardware to train AI models has increased in tandem with the increase in the model complexity over the recent years. Graphics Processing Unit (GPU) is one such hardware that is capable of paralellizing operations performed on a large chunk of data. Companies like Nvidia, AMD, and Google have been constantly scaling-up the hardware performance as fast as they can. Nevertheless, there is still a gap between the required processing power and processing capacity of the hardware. To increase the hardware utilization, the software has to be optimized too. In this paper, we present some general GPU optimization techniques we used to efficiently train the optiGAN model, a Generative Adversarial Network that is capable of generating multidimensional probability distributions of optical photons at the photodetector face in radiation detectors, on an 8GB Nvidia Quadro RTX 4000 GPU. We analyze and compare the performances of all the optimizations based on the execution time and the memory consumed using the Nvidia Nsight Systems profiler tool. The optimizations gave approximately a 4.5x increase in the runtime performance when compared to a naive training on the GPU, without compromising the model performance. Finally we discuss optiGANs future work and how we are planning to scale the model on GPUs.

Development of an FPGA‐Based Pulse‐Height Analyzer for Scintillation Detectors in Gamma Energy Spectroscopy

This study presents the development of a Pulse Height Analyzer (PHA) using an FPGA‐based hardware platform, specifically the National Instruments MyRIO embedded device, for radiation detectors. Electronic pulses generated by the detector when exposed to radiation are triggered, digitized, and transferred to a data buffer. A pulse height analysis tool categorizes these pulses and stores pulse‐height information in registers or channels, enabling the construction of a pulse‐height distribution. The data of pulse‐height distribution is then recorded on a computer via a user‐friendly interface. The Pulse Height Analyzer was implemented using a 3‐inch by 3‐inch NaI(Tl) scintillation detector for gamma energy measurements, employing standard radioisotopes Na‐22 and Co‐60. Gamma energy spectra were acquired and analyzed. Our results demonstrate that the achieved energy resolution is comparable to that of the commercial Pulse Height Analyzers, such as EASY‐MCA 2K, a product of AMETEK Inc. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Facile synthesis of RGO/TiO2 heterojunction on SiNWs on Si chip for near infrared detector

Here, a ternary nanostructure-based heterojunction was developed for the detection of infrared (IR) radiation in near wavelength range. During materials synthesis process, silicon nanowires (SiNWs) were developed using metal assisted chemical etching (MACE) technique whereas reduced graphene oxide (RGO) sheets and TiO2 nanoparticles were synthesized by chemical vapour deposition (CVD) and solvothermal method, respectively. Thereafter, RGO/TiO2 nanostructure was deposited over SiNWs to form a heterojunction. To analyse the stoichiometry, morphology, and internal structure, various characterization techniques were performed such as scanning electron microscope (SEM), transmission electron microscope (TEM), Energy dispersive spectrometer (EDS), X-Ray Diffractometer (XRD), UV–Vis spectrophotometer and X-Ray Photoelectron Spectrometer (XPS). The RGO/TiO2@SiNWs nanostructure-based heterojunction was used for the detection of near IR radiation where the responsivity (R) was found to be 17.22 × 10−3 A/W and detectivity (D) was measured to be 0.23 × 1011 Jones with response time < 1 s and recovery time < 3 s. These results were found comparatively better than pristine RGO@Si and RGO@SiNWs nanostructure-based sensors used for the near IR detection under same conditions. The photocurrent response was also recorded with 5 ON/OFF cycles which depicted a good reproducibility of the prepared detector. Hence, the SiNWs on Si chip based highly sensitive and selective photodetector can be used to set a new milestone for various near IR applications.

Cd0.90Mn0.10Te single crystal for γ – Ray detector application: A comprehensive analysis of structural and compositional homogeneity

This study provides a comprehensive examination of the Cd0.90Mn0.10Te (CMT) single crystal in its role as a radiation detector. Covering aspects from the growth process to detector performance, the primary emphasis is placed on ensuring the uniformity of composition along the growth axis. A cost-effective custom-built vertical Bridgman (VB) setup is developed for the growth of highly homogeneous Cd0.90Mn0.10Te (CMT) single crystal. CMT single crystals of 10 mm diameter and 130 mm length with near uniform stoichiometry along the growth axis were grown using VB method. Laue diffraction confirms the single crystallinity of the grown crystal. The measured lattice constant is comparable to the theoretical value calculated using Vegard’s law. The two mode vibrations of the CdTe and MnTe sublattices were confirmed by Raman spectroscopy. The observed high optical transmittance in the mid-infra-red (IR) region and a nearly constant bandgap of ∼1.6 eV for the wafers taken at different locations along the growth axis reveals the IR transparency and compositional uniformity of the grown crystal. The energy dispersive X-ray spectroscopy proved that the elemental distribution is uniform in the grown crystal. The IR microscopic imaging shows Te inclusions with a number density in the range of ∼2.6–4.5 × 104 cm−2. The resistivity of the CMT crystal for all wafers was found to be in the order of 109 Ωcm. The γ–ray spectral resolution of ∼22 % of 59.5 keV irradiation from 241Am source is achieved.

Assessment of the technical state of mining machinery and devices with the use of diagnostic methods

Abstract In this article, one of the possible, effective methods of assessing the technical state of mining machinery and devices has been presented. The article's main goal is to show the possible methods and ways of measuring temperature, oscillations, and vibrations generated during the operation of mining equipment and machines’ gears, which are possible in underground conditions. Devices measuring temperatures without coming into contact with the given object are built based on different types of infrared radiation detectors or matrixes of such detectors. Thermal imaging devices picture the temperature distribution on the entire surface instead of pyrometers, which measure temperatures at a given point. However, vibrations and oscillations generated by the work of gears of devices and machinery have been made using a vibrometer pen and a machine condition tester, after which the obtained measurements were used to diagnose the degradation of individual elements of those machines. Such an assessment of the degradation of individual elements of machines in production conditions has been applied with positive results in one of the mines of the Polish Mining Group (Polska Grupa Górnicza – PGG).

Bright Innovations: Review of Next-Generation Advances in Scintillator Engineering.

This review focuses on modern scintillators, the heart of ionizing radiation detection with applications in medical diagnostics, homeland security, research, and other areas. The conventional method to improve their characteristics, such as light output and timing properties, consists of improving in material composition and doping, etc., which are intrinsic to the material. On the contrary, we review recent advancements in cutting-edge approaches to shape scintillator characteristics via photonic and metamaterial engineering, which are extrinsic and introduce controlled inhomogeneity in the scintillator's surface or volume. The methods to be discussed include improved light out-coupling using photonic crystal (PhC) coating, dielectric architecture modification producing the Purcell effect, and meta-materials engineering based on energy sharing. These approaches help to break traditional bulk scintillators' limitations, e.g., to deal with poor light extraction efficiency from the material due to a typically large refractive index mismatch or improve timing performance compared to bulk materials. In the Outlook section, modern physical phenomena are discussed and suggested as the basis for the next generations of scintillation-based detectors and technology, followed by a brief discussion on cost-effective fabrication techniques that could be scalable.

Development of a phoswich detector utilizing bismuth germanate crystal scintillator and polyethylene naphthalate scintillation film

In this study, we present the development of a phoswich detector system employing a Bismuth Germanate (BGO) crystal scintillator in combination with a Polyethylene naphthalate (PEN) film plastic scintillator. Phoswich detectors can contribute to various applications, including radiation monitoring, medical imaging, and nuclear physics experiments, due to their ability to discriminate between different types of radiation. The thin PEN film is sensitive to α and β radiation, while the BGO scintillator exhibits good γ radiation detection efficiency. The incident radiation type and its energy can be determined by analyzing the difference in decay times between these two scintillators. This paper presents an analysis of the detector’s response to α, β, and γ radiation, and the particle tagging efficiencies are to be over 99.9%, 92%, and 99.8%, respectively.

Anisotropic optoelectronic properties of lead-free Cs3Bi2I9 single-crystal photodetectors

Lead-free halide perovskites have attracted widespread research interest due to their excellent optoelectronic properties and environmental friendliness. As one of the bismuth iodide compounds, Cs3Bi2I9 perovskite has been extensively explored in the field of photovoltaic devices and radiation detectors due to their non-toxic lead-free components and excellent stability. In this work, we successfully grow large-sized Cs3Bi2I9 single crystals (SC) with (l00) and (00l) crystal exposure facets by inverse temperature crystallization method. Under 525 nm light illumination with the intensity 15 mW cm−2 and 7 V bias, the (l00) Cs3Bi2I9 SC shows 2 times higher photocurrent, 3.6 times higher responsivity, and 2.8 times higher detectivity than the (00l) Cs3Bi2I9 SC, respectively. Superior response time in the scale of millisecond is obtained in both (l00) and (00l) Cs3Bi2I9 SCs. Based on the first-principle calculation, the (l00) SC possesses a higher charge distribution density and a wider dispersion distribution than (00l) SC, suggesting that more electrons in the (l00) SC can be excited in a wider range. The tighter arrangement of Cs+ and [BiI6]− octahedra in the (l00) SC than (00l) SC leads to the anisotropic photoelectric performance in (l00) and (00l) Cs3Bi2I9 SCs. Our results provide a strategy for the oriental growth of Cs3Bi2I9 SCs and the design of anisotropic optoelectronic devices with excellent performance.

Mn(II)-Based Metal Halide with Near-Unity Quantum Yield for White LEDs and High-Resolution X-ray Imaging.

Metal halides have drawn great interest as luminescent materials and scintillators due to their outstanding optical properties. Exploring new types of phosphors with easy production processes, excellent photophysical properties, high light yields, and environmentally friendly compositions is crucial and quite challenging. Herein, a novel Mn(II)-based metal halide (4-BTP)2MnBr4 was produced using a facile solvent evaporation method, which exhibited a strong green emission peaking at 524 nm from the d-d transition of tetrahedral-coordinated Mn2+ ion and a near-unity quantum yield. The prepared white light-emitting diode device has a wide color gamut of 100.7% NTSC with CIE chromaticity coordinates of (0.32, 0.32). In addition, (4-BTP)2MnBr4 demonstrates excellent characteristics in X-ray scintillation, including a high light yield of 98 000 photons/MeV, a sensitive detection limit of 37.4 nGy/s, excellent resistance to radiation damage, and successful demonstration of X-ray imaging with high resolution at 21.3 lp/mm, revealing the potential for application in diagnostic X-ray medical imaging and industry radiation detection.

Bright and durable scintillation from colloidal quantum shells

Efficient, fast, and robust scintillators for ionizing radiation detection are crucial in various fields, including medical diagnostics, defense, and particle physics. However, traditional scintillator technologies face challenges in simultaneously achieving optimal performance and high-speed operation. Herein we introduce colloidal quantum shell heterostructures as X-ray and electron scintillators, combining efficiency, speed, and durability. Quantum shells exhibit light yields up to 70,000 photons MeV−1 at room temperature, enabled by their high multiexciton radiative efficiency thanks to long Auger-Meitner lifetimes (>10 ns). Radioluminescence is fast, with lifetimes of 2.5 ns and sub-100 ps rise times. Additionally, quantum shells do not exhibit afterglow and maintain stable scintillation even under high X-ray doses (>109 Gy). Furthermore, we showcase quantum shells for X-ray imaging achieving a spatial resolution as high as 28 line pairs per millimeter. Overall, efficient, fast, and durable scintillation make quantum shells appealing in applications ranging from ultrafast radiation detection to high-resolution imaging.

Characterization of pure organic NTI crystals for direct x-ray detection

Accurate detection of x-ray radiation is essential for tissue equivalence detection and safety control during medical radiotherapy. Here, a promising radiation detector based on organic 1,8-naphthalimide (C12H7NO2, NTI) single crystals is proposed. NTI single crystals with dimensions of 8 × 2 × 1 mm3 were synthesized by an optimized solvent-cooling method, and the crystal structure was characterized to elucidate the anisotropy mechanism. The coplanar detector made by NTI has a leakage current of less than 0.1 pA at an electric field strength of 1 kV cm−1 and provides excellent detection of 5.49 MeV α-particles (241Am) with a full-energy peak resolution of up to 32.3%. The calculated electron mobility (μe) and electron mobility-lifetime product (μτ)e were 7.9 cm2 V−1s−1 and 1.56 × 10−6 cm2 V−1, respectively. Additionally, the detection limit of the NTI detector was 0.35 µGy s−1 in the electric field strength range of 0.2–1.0 kV cm−1 under a 20 kV x-ray beam with a high sensitivity of 56.2 μC Gy−1cm−2. Consequently, the NTI detector achieves an excellent spatial resolution of 0.8–0.9 lp mm−1 in terms of x-ray imaging capability.

The Charged Particle Detection System of the SRD Module onboard the China Space Station

The radiation field environment outside the Earth varies greatly with space location and the cycle of solar activity, and the radiation environment near the space station’s orbit is much more complex than that on the Earth’s surface. Various high-energy cosmic ray particles and secondary particles produced by them and the bulkhead of the space station greatly impact the health of astronauts and the working conditions of instruments. Each aircraft is always equipped with some dedicated radiation monitoring instruments to assess the exposure risk for astronauts, and to analyze the causes of instrument failures. The Space Radiation Detector Module (SRDM) is working in the China Space Station (CSS) to measure the radiation environment inside, including two parts: the Charged Particle Detection System (CPDS) and the Neutron Detection System (NDS). The CPDS, which is the main content of this paper, contains a detector unit, that consists of three silicon detectors a BGO calorimeter, and the corresponding readout electronics unit of the detector unit. Ground test results show that the detection system can detect various charged particles from hydrogen to nitrogen ions with an energy resolution of less than 15%. The actual measurement results for a period in orbit show that the main types of charged particles in the cabin are protons and α particles, with measured energies ranging from 0.8 to 265.2 MeV for protons and from 1.0 to 61.6 MeV/A for α particles(where A is the mass number), and linear energy density (LET) range mainly from 1.0 to 612.4 keV/μm. The radiation environment data measured in CSS can provide an important reference value for the exposure risk, life science experiments, and the status of instruments on board.

A quasi-spherical optical module QSM-6M based on the Hamamatsu R877 PMT for the detection of Cherenkov radiation in water

In this paper, we describe the quasi-spherical optical module QSM-6M to detect Cherenkov radiation in water. The module is based on six photomultiplier tubes (PMTs) with flat photocathodes Hamamatsu R877. We discuss the results of the photomultiplier testing, as well as the choice of the high-voltage divider providing the PMT dynamic range from 1 to 105 photoelectrons. The techniques for studying QSM-6M characteristics, as well as the results of the underwater testing of the module for an 18-month period are presented. We also present the results of the analysis of the QSM-6M response to single-muon and multiparticle events detected by the installations of the Experimental Complex NEVOD.