Detection Of Ionizing Radiation Research Articles

Application of area monitors and scintillating detectors in the development of CBRN defense reconnaissance vehicles

This study describes the use of ionizing radiation detectors in a Brazilian Army reconnaissance vehicle (RV), used in area monitoring actions based on the occurrence of a radiological event. Two scintillating detectors, NaI and LaBr3, were used to carry out field measurements of surveying for different distances from a simulated detector position in the vehicle, in order to compare the energy spectra obtained in each measurement system. The Brazilian Army Technological Center (Centro Tecnológico do Exército - CTEx) region was chosen to carry out the measurements. The meteorological information was annotated to verify the conditions into which the experimental apparatus would be submitted. The results suggest that both the NaI and LaBr3 scintillating detector could be used in radiological emergency response RV, offering satisfactory responses in the gamma radiation detection. However, the NaI detector was chosen considering the wide network of technical assistance and its low operational cost. The relevance of this investigation shows the importance of planning responses in emergency situations and the influence of efficient instrumentation in the measurement processes.

Energy band-gap inhomogenities and defect states affecting carrier transport at low temperatures in Thallium Bromide

We report analysis of carrier transport phenomena in Thallium Bromide single-crystals-based ionizing radiation detectors. It is demonstrated that these phenomena, despite the used mature material growth technology, are in general notably affected by still present material macro-inhomogeneities. The inhomogeneities, which are well discerned by optical microscopy and AFM, reveal themselves in carrier transport, causing the space-charge-limited currents, appearance of the built-in polarization voltages and long lasting (photo-) conductivity relaxations at low temperatures. They could be associated with the existing charge trapping states and potential inhomogeneities of the band gap edges, which create potential fluctuations of up to 240 meV. These fluctuations become thermally quenched by the thermally generated carriers above about 260 K.

Nanostructured Glass Composite for Self‐Calibrated Radiation Dose Rate Detection

AbstractThe wide applications of ionizing radiation in various important technologies such as 3D industrial tomography, mammography, and small‐animal micro‐CT with low energy X‐ray have increased the demand for precise radiation measurement. Detection technologies have undergone remarkable progress, but most of them strictly rely on the complicate calibration process, thus remarkably limiting their applications. Here, a nanostructured glass composite system for self‐calibrated radiation dose rate detection (at 40 keV X‐ray) is described. Results show that the in situ precipitation of LiGa5O8 nano‐domains from glass composite results in unique emission centers at ≈496 and ≈718 nm with distinct ionizing radiation response. Subsequently, the radiation level is directly assessed by comparing the radiative transition ratio of these two centers. The nanostructured glass composite can also be constructed into fiber, which exhibits perfect core‐clad configuration and maintains excellent optical activity. The novel principle device with self‐calibrated function is successfully constructed, and the application for online radiation monitoring is demonstrated. The results not only provide an alternative opportunity for developing the next generation of ionizing radiation detection system, but also suggest a powerful pathway for the creation of new optical function through nanocrystallization of glass.

Charge carrier mobility of halide perovskite single crystals for ionizing radiation detection

Halide perovskites have recently emerged as promising semiconductor materials for several applications including solar cells, light-emitting diodes, and radiation detectors. The charge carrier transport properties, which could be evaluated by the mobility-lifetime (mu-tau or μ-г) product, serve an important role for the development of halide perovskites for radiation detection applications. In this Perspective, we first explain the charge transport mechanism and the limiting factors that determine the intrinsic charge carrier mobility in halide perovskite single crystals. Then, we overview the techniques and methods that have been employed for evaluating the charge carrier mobility (for both electrons and holes). Finally, we discuss the discrepancy in the experimentally determined carrier mobility from the literature for halide perovskite single crystals, and provide a perspective on future developments for carrier mobility enhancement.

Investigations into the basic properties of different passive dosimetry systems used in environmental radiation monitoring in the aftermath of a nuclear or radiological event

Due to the need for harmonization of passive dosimetry and the requirements of the international standards in the area of environmental monitoring in radiation protection, multiple types of various passive dosimetry systems based on different ionizing radiation detection mechanisms were subjected to extensive performance testing. In the scope of the EMPIR project 16ENV04 Preparedness, the performance of 12 passive dosimetry systems was examined in radiation fields of different photon energies, angles of incidence and ambient dose equivalent rates in order to estimate their performance in the almost omni-directionally and energetically broad radiation field of the natural environment. The use of different detectors, holders, calibrations, measurement procedures and uncertainties, leads to differences in the measured data. Prior investigations and harmonization of passive dosimetry systems are necessary to achieve reliable and comparable dose measurements in Europe.

On the limit of the accuracy of timе stamp at the detection of annihilation γ-quanta with a scintillation detector

An influence of the various relaxation processes of the electronic excitations causing the scintillation in the crystalline compounds under ionising radiation is analysed. It was found that the intracenter relaxation of electronic excitations in the luminescence ion forms a physical limit for the time resolution of the scintillation detector. The limit of the time resolution, which can be provided when measuring the ionising radiation with a scintillation detector, has been established by simulation. A comparison of the time resolution limits for various errors by the electronic part of the ionising radiation detector is performed. It is shown that inorganic scintillation materials based on single crystals activated by cerium ions have a limit of 10 ps, while self-activated scintillators with low yield and short scintillation kinetics may show results not worse than 20 ps. It has been demonstrated that a further increase in the scintillation yield while keeping the short kinetics in self-activated materials can provide a better time resolution in comparison with Ce-activated materials in future detectors.

Neural network approach for efficient calculation of the current correction value in the femtoampere range for a new generation of ionizing radiation monitors at CERN

The European Organization for Nuclear Research (CERN) conducts experiments that involve colliding beams of particles either together or into stationary targets. During these interactions, stray radiation may be generated. The ionizing radiation detectors installed at several locations close to the beam lines and targets of these areas allow CERN radiation protection by precisely monitoring radiation levels. Radiation monitoring is one of the main responsibilities of the Radiation Protection Group and a crucial task to indirectly ensure safety at CERN and its surrounding environment.After 30 years of reliable service, the ARea CONtroller (ARCON) system has reached the end of its lifecycle. A new generation of radiation monitors called CROME (Cern RadiatiOn Monitoring Electronics) has been developed at CERN. These monitors incorporate embedded processing capabilities in order to execute various algorithms, such as evaluation of the real electrical current generated by the radiation detectors when they are subject to ionizing fields. This paper presents a case study of a new method for offset correction of a femtoampere current. At this scale, the measured current is sensitive to surrounding environmental factors, such as temperature, vibration. and the permittivity of the air. To guarantee the high precision of calculation and real-time operation, and to overcome the limitations of the field-programmable gate array (FPGA) platform used, a novel method utilizing a neural network approach is proposed. The results obtained with a new model are very satisfactory in terms of both accuracy of prediction and reduced computational complexity. This may encourage further usage of neural networks in safety-critical systems.

Self-assembled eco-friendly metal halide heterostructures for bright and color-tunable white radioluminescence

Scintillators with color-tunable radioluminescence have attracted great attention due to the advantage of satisfying needs required by different radiation detection applications. However, while most traditional scintillators achieve efficient radioluminescence through exciton migration or activator-assisted recombination mechanism, the challenges relating to spectral modulation remain. Here, a composite scintillator consisting of a eco-friendly metal halide heterostructure demonstrates color-tunable radioluminescence with color temperature ranging from 2,505.6 K to 14,215.9 K. Under X-ray irradiation, the composite scintillator emits bright white light with a color rendering index of 92.6 set and a luminescent yield of 21,400 photons/MeV, which originates from self-assembled metal halide heterostructure and efficient energy transfer. The performance exhibited by the composite heterostructure material provides and proves a feasible strategy for realizing color-tunable scintillators in ionizing radiation detection.

Comparative Studies of Ionizing Radiation Detectors Made on the Basis of Various Types of Diamond Plates

The results of experiments on the study of polarization phenomena and the charge collection efficiency in test structures of diamond ionizing radiation detectors using diamond plates of various types, including single-crystal NRNT-type, single-crystal CVD-type, as well as polycrystalline type, when exposed to alpha-radiation with an energy of 5.5 MeV are presented. Studies have demonstrated the existence of a number of problems with the device quality of diamond plates that affect the performance of spec-trometric-type detectors.

EFFECT OF DEFECTS ORIGINATING UNDER THE PROTON IRRADIATION ON THE ELECTROPHYSICAL AND DETECTOR PROPERTIES OF CdTe:Cl AND CdZnTe

The work is dedicated to studying by computer modeling the mechanisms of the influence of radiation defects, originating under high energy proton irradiation, on the resistivity ρ, lifetime of nonequilibrium electrons n and holes p in CdTe:Cl and Cd0.9Zn0.1Te, and charge collection efficiency η of room temperature ionizing radiation detectors based on these materials. The effect of recombination at deep levels of radiation defects on the degradation of n, p, and  of detectors based on CdTe:Cl and Cd0.9Zn0.1Te was studied. Energy levels of radiation defects also substantially effect on compensation degree of semiconductor decreasing ρ. The main factors affecting the abrupt or gradual decrease in the resistivity and charge collection efficiency of these detectors during their bombardment by high-energy protons, leading to complete degradation of their recording ability, were found. The important role of purity and deep donor concentration in initial state of the detector material was indicated.

HARDWARE AND SOFTWARE COMPLEX FOR MEASURING HARD X-RAY RADIATION ON THE TORSATRON “URAGAN-2M”

This paper presents an automated measuring system for radiation monitoring and measurement of hard X-ray radiation in real time on the "Uragan-2M" torsatron. The system includes an ionizing radiation detector based on a scintillator and a photomultiplier tube, equipment for preliminary processing and normalization of detector signals, and a microcontroller unit for control, measurement and processing.

Design considerations for a new generation of SiPMs with unprecedented timing resolution

The potential of photon detectors to achieve precise timing information is of increasing importance in many domains, PET and CT scanners in medical imaging and particle physics detectors, amongst others. The goal to increase by an order of magnitude the sensitivity of PET scanners and to deliver, via time-of-flight (TOF), true space points for each event, as well as the constraints set by future particle accelerators require a further leap in time resolution of scintillator-based ionizing radiation detectors, reaching eventually a few picoseconds resolution for sub MeV energy deposits. In spite of the impressive progress made in the last decade by several manufacturers, the Single Photon Time Resolution (SPTR) of SiPMs is still in the range of 70–120 ps FWHM, whereas a value of 10 ps or even less would be desirable. Such a step requires a break with traditional methods and the development of novel technologies. The possibility of combining the extraordinary potential of nanophotonics with new approaches offered by modern microelectronics and 3D electronic integration opens novel perspectives for the development of a new generation of metamaterial-based SiPMs with unprecedented photodetection efficiency and timing resolution.

Inorganic Halide Perovskitoid TlPbI3 for Ionizing Radiation Detection

AbstractRoom temperature semiconductor detector (RTSD) materials for γ‐ray and X‐ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI3 are reported on. This compound crystallizes in the ABX3 non‐perovskite crystal structure with a high density of d = 6.488 g·cm–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally‐activated defects. High‐quality TlPbI3 single crystals of centimeter‐size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈1012 Ω·cm is readily obtainable, and detectors made of TlPbI3 single crystals are highly photoresponsive to Ag Kα X‐rays (22.4 keV), and detects 122 keV γ‐rays from 57Co radiation source. The electron mobility‐lifetime product µeτe was estimated at 1.8 × 10–5 cm2·V–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI3.

Análise de parâmetros π-híbridos de um MOSFET com encapsulamento TO-220 sob feixes de raios X para diagnóstico médico

Nas últimas décadas o MOSFET (Metal Oxide Semiconductor Field Effect Transistor) tem sido utilizado como detector de radiação ionizante, principalmente em aplicações dosimétricas em radioterapia. A base do método de funcionamento de tal dispositivo eletrônico em radioterapia consiste em mensurar a variação da tensão de limiar do MOSFET, pois este parâmetro elétrico é proporcional à dose de radiação ionizante depositada no dispositivo. O objetivo deste trabalho é apresentar um método inovador de medição da dose de radiação ionizante por meio da medição da variação de alguns parâmetros π-híbridos de um MOSFET. Foram analisados apenas transistores com encapsulamento TO-220 e dois tipos de polaridades distintas: canal n e canal p. Os dispositivos foram submetidos aos feixes de raios X cuja energia está na faixa aplicada ao diagnóstico médico. Os resultados mostraram que os parâmetros π-híbridos transcondutância e uma capacitância variam com a dose acumulada de radiação até o limite de 100 Gy.

Evaporated Perovskite Thick Junctions for X-Ray Detection.

X-ray detection is widely utilized in our daily life, such as in medical diagnosis, security checking, and environmental monitoring. However, most of the commercial X-ray detectors are based on inorganic semiconductors, e.g., Si, CdTe, and Ge, which require complex and costly fabrication processes. Metal halide perovskites have recently emerged as a set of promising candidates for ionizing radiation detection, owing to the high attenuation coefficient, long carrier lifetime, and excellent charge transport properties. Perovskite single crystals have been successfully implemented in X-ray detection, but the fragile single crystals limit the device fabrication and the integration with a read-out circuit. In addition, it is hard to reach inch-size single crystals for real application. Flexible devices based on perovskite films or composite films have also been reported, but either the thickness or charge transport properties are limited by the solution processes. In this work, we introduced thermal co-evaporation to deposit highly efficient formamidinium lead iodide perovskite films. Considering the trade-off between X-ray absorption and charge transport, we optimized the active layer thickness and achieved large-area and flexible X-ray detectors with state-of-the-art device performance, including extremely low dark current and noise, fast response, and high sensitivity of 142.1 μC Gyair-1 cm-2.

Efficient sky-blue radioluminescence of microcrystalline Cs3Cu2I5 based large-scale eco-friendly composite scintillators for high-sensitive ionizing radiation detection

A high-efficiency sky-blue radioluminescence, large-size, eco-friendly hybrid scintillator made of CsI:Na and Cs3Cu2I5 single crystals is expected to become a potential ionizing radiation detection scintillator.

Response of HPRT Gene Fragment Functionalized Gold Nanoparticles to Gamma Ray Irradiation.

Radiation-sensitive biomolecules are highly significant for studying biological effects of radiation and developing ionizing radiation detectors based on biomolecules. In this work, we selected hypoxanthine phosphoribosyl transferase gene fragments sensitive to gamma-ray irradiation as a sensing element for radiation detection. The end was modified with thiol groups. The thiol-modified oligonucleotide sequences were coupled to the surface of gold nanoparticles by Au-S covalent bonds. The DNA attached to the surface of gold nanoparticles forms a DNA-AuNPs assembly through base pairing. The assembly was irradiated by gamma rays. And its response to radiation was studied with ultraviolet-visible spectroscopy and surface-enhanced Raman scattering (SERS) spectroscopy techniques. SERS spectroscopy and ultraviolet spectroscopy can detect the response of the DNA-AuNPs assembly to gamma-ray irradiation below 100 and 100 - 250 Gy, respectively. The results indicated that it was feasible to develop a new approach of gamma-ray detectors using biomolecular assemblies of gold nanoparticles.

CsPbBr3 perovskite detectors with 1.4% energy resolution for high-energy γ-rays

Halide perovskite semiconductors are poised to revitalize the field of ionizing radiation detection as they have done to solar photovoltaics. We show that all-inorganic perovskite CsPbBr3 devices resolve 137Cs 662-keV γ-rays with 1.4% energy resolution, as well as other X- and γ-rays with energies ranging from tens of keV to over 1 MeV in ambipolar sensing and unipolar hole-only sensing modes with crystal volumes of 6.65 mm3 and 297 mm3, respectively. We report the scale-up of CsPbBr3 ingots to up to 1.5 inches in diameter with an excellent hole mobility–lifetime product of 8 × 10−3 cm2 V−1 and a long hole lifetime of up to 296 μs. CsPbBr3 detectors demonstrate a wide temperature region from ~2 °C to ~70 °C for stable operation. Detectors protected with suitable encapsulants show a uniform response for over 18 months. Consequently, we identify perovskite CsPbBr3 semiconductor as an exceptional candidate for new-generation high-energy γ-ray detection. Energy resolution of high-energy photon detectors is desired for applications ranging from biomedical imaging to homeland security. In this work, perovskite-based γ-ray detection with 1.4% energy resolution is demonstrated.

Verificación funcional de detectores de radiación tipo Geiger-Müller en medicina nuclear y radiofarmacia del Instituto Nacional de Cancerología: una propuesta para el aseguramiento de la calidad de equipos de protección radiológica

Basado en la implementación del plan de aseguramiento de la calidad, el objetivo principal de este estudio es realizar el seguimiento y análisis de las verificaciones funcionales realizadas a los equipos detectores de radiación ionizante del Servicio de Medicina Nuclear y del Servicio de Radiofarmacia del Instituto Nacional de Cancerología E. S. E. (INC). Los equipos de estudio fueron dieciséis detectores tipo Geiger-Müller, fijos y portátiles, con fuentes certificadas selladas tipo gotero y planas para la recolección de mediciones realizadas por un periodo de tres años. Como resultado, se encontraron comportamientos variables siempre en el rango del 20 % del error porcentual existentes entre el valor medido y el valor de referencia de cada equipo. El estudio permite concluir que los detectores muestran un comportamiento esperado dentro de la reproducibilidad propia del detector y las desviaciones propias de los diferentes operadores; sin embargo, y con el fin de minimizar las variaciones, es imprescindible contar con un programa de aseguramiento de la calidad de los equipos detectores de radiación que vele por la idoneidad de las medidas realizadas.

Ranking of commercial photodiodes in radiation detection using multiple-attribute decision making approach

Recent studies have shown that silicon PIN photodiodes can be used in the area of detecting ionizing radiation. Selection of proper photodiode as ionizing radiation detector is crucial. In this paper the SMART technique as a subset of multiple-attribute decision making (MADM) approaches is employed in order to rank detectors. Using this method leads to the optimized initial selection of detector. The process of ranking is based on pre-defined attributes such as active area, breakdown voltage, minimum wavelength in the spectral range, wavelength with maximum response in spectral range, dark current, junction capacitance, and power dissipation of photodiodes. Evaluation results of a set of photodiodes show that PS100-6 and S1223-01 are the best and second-best alternatives, respectively. Considering commercial contemplations, cost could also be added to the aforementioned attributes. In this case, BPV10 and BPW34 are found as the best and second-best alternatives.