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BackgroundLead-free/lead-composite nuclear radiation protection materials are becoming increasingly prevalent in military applications to safeguard the health and safety of military personnel. Currently, accurate measurement and tracing of the shielding performance of military nuclear radiation protective clothing is difficult.PurposeThis study aims to measure lead equivalent in nuclear radiation protection materials for satisfying the radiation performance evaluation requirements of international mainstream military radiation protective clothing.MethodsFirstly, a device to measure lead equivalence in protective clothing was developed. Then, the reference radiation mass for lead equivalence at a photon energy of 130 keV was determined using a combination of Monte Carlo simulation and experimental measurements. Finally, the shielding performances of a standard lead sheet were assessed using developed device under narrow beam conditions, and shielding performances of military nuclear radiation protective clothing materials produced by a few manufacturers were tested in the same conditions.ResultsEvaluation results show the relative expanded uncertainty of lead equivalent measurement results for standard lead sheet and military nuclear radiation protective clothing samples correspond to 4.2% (k=2).ConclusionsThis study identifies measurement conditions for subsequent performance tests of additional military nuclear radiation protective materials prior to delivery.

BackgroundThe solar X-ray detector (SXD) is the main scientific instrument onboard the Macau Science Satellite-1B (MSS-1B). It consists of two parts—a soft X-ray detection unit and a hard X-ray detection unit—with a dual-channel design comprising a silicon drift detector (SDD) and a cadmium zinc telluride detector (CZT). Both the precise energy spectrum and intensity of the Sun can be simultaneously obtained by the SXD, hence to quantify the level of solar flares and study their evolutionary process.PurposeThis study aims to calibrate the detection efficiencies of the SDD and CZT, so as to invert the observed data for obtaining real solar X-ray data.MethodsThe Monte Carlo code MCNP5 (Monte Carlo N-Particle 5) was employed to calculate the SDD and CZT efficiencies by simulation. Soft and hard X-ray detection efficiency calibration experiments were performed using a monochromatic X-ray ground calibration facility via relative measurement methods.ResultsThe experimental results for the SDD-1 and CZT-1 efficiency calibration agree well with the predicted results of the simulation. In particular, the maximum relative error between the experimental and simulated efficiencies of SDD-1 dose not exceed 3.59%@16 keV, and the maximum relative error between the experimental and simulated efficiencies of CZT-1 dose not exceed 9.54%@120 keV. The relative expanded uncertainty of the monochromatic X-ray flow intensity measurement is 3.8% (k=2), and the uncertainty of the simulation results for the SXD is 0.12%.ConclusionsThis study provides not only data support for SXD onboard MSS-1B satellite, but also valuable guidance for the calibration of other astronomical satellites' detectors in the future.

BackgroundA CdZnTe (CZT) detector is a compound semiconductor detector with a high atomic number and high detection efficiency, it can be used at room temperatures to detect short wavelength radiation such as X-ray and γ ray.PurposeThis study aims to investigate the factors affecting the energy spectrum characteristics of the CZT detector.MethodsThe geometric model of the detector was established by using Geant4 software, and the intrinsic detection efficiency and absorption rate of CZT crystal in the planar size of 10 cm×10 cm were simulated. The charge collection efficiency of the crystal was calculated using the Hecht formula and the γ-ray energy spectrum was obtained by collecting the deposition energy and position information in the crystal. By analyzing the physical properties of crystals, the impact of physical properties on detector performance was explored.ResultsSimulation results show that incomplete charge collection significantly influences the spectral performance of the detector. When the γ ray energy is less than 50 keV, the spectrum is not affected by hole wake whilst the influence of hole wake is more obvious when the energy is between 50 keV and 100 keV. The energy spectrum is gradually aggravated by the influence of hole wake when the γ ray energy is above 100 keV.ConclusionsThis effect of hole wake for CZT detector can be reduced by increasing the bias voltage, but the increased bias voltage shifts the spectrum's peak, and the shift amount is determined by the maximum charge collection efficiency of the crystal.

X-ray and γ-ray detection have been extensively studied and applied in medical imaging, security inspection, homeland security, non-destructive testing and other various fields. Perovskite materials have become excellent candidates for radiation detector devices due to their high radiation absorption coefficient, high carrier mobility-lifetime product and defect tolerance. The solution method offers significant advantages in the preparation of perovskite materials. It is a cost-effective approach that can be carried out at low temperatures or under ambient conditions. Additionally, it is also easier to implement for industrial production. This method plays a crucial role in optimizing the material system and achieving the preparation of high quality and large area crystal materials in the future. This paper analyzes the effects of crystal growth and material composition on radiation detection performance, focusing on the solution preparation of perovskite materials. The study aims to improve radiation detection performance by optimizing crystal growth quality and device structure design. Additionally, it also summarises the challenges faced by perovskite materials in the field of radiation detection and suggests future research directions. The results of this study are expected to serve as a reference for the industrialization of perovskite materials in the field of radiation detection. [ABSTRACT FROM AUTHOR]

BackgroundCalibration is an important way to assess the performance of radiation monitoring instruments and to ensure their accuracy and reliability for measurement.PurposeThis study aims to solve the traceability problem of dose meters at low dose rate.MethodsFirst of all, reference radiation masses of 55 kV, 70 kV, 100 kV, 170 kV, 240 kV were established and their energy spectra were measured by adding additional filtering to the X-ray radiation field. Then, the energy spectrum of each radiative mass was simulated by the EGS (Electron Gamma Shower) program to obtain the radiative mass half-value layer and the average energy. Finally, the kerma rate at the reference point was measured by using a large volume spherical ionization chamber, followed by calibration of conventional radiation environmental monitoring instruments.Results & ConclusionsThe results showed that the relative deviation between the simulated energy spectra and measured spectra does not exceed 1.6% and the dose rate decreases with more additional filtration. The established dose rates for the radiation masses ranged from 606 nGy·h-1 to 4 451 nGy·h-1 the uncertainty is 6.0% (k=2). The uncertainty of the calibration measurement results of the high-pressure ionization chamber 6150AD dose rate meter is 7.0% (k=2).

BackgroundLow energy X-rays are often used in superficial radiotherapy, its air kerma or absorbed dose to water is usually measured with a plane-parallel ionization chamber.PurposeThis study aims to investigate the response of the plane-parallel ionization chamber in the low energy X-ray calibration process and the scattering caused by the change of the radiation field.MethodsFirst of all, Monte Carlo simulation of four reference radiations (30 kV, 25 kV, 50 kV(b) and 50 kV(a)) was carried out in the low-energy X-ray standard radiation field. Then, two commonly used plane-parallel ionization chambers. i.e., PTW23344 and PTW23342, were calibrated and measured in air and phantom respectively by experiment, and the size of radiation field was changed by using different secondary apertures.ResultsThe readings of the two ionization chambers increase with the increase of the diameter of the radiation field, but the overall trend is gradually flattening. Ratios between chamber's readings in air and in phantom of the two ionization chambers decreases as the diameter of the radiation field decreases, and the overall trend gradually flattening. The average increase in the calibration coefficient of the absorbed dose to water in the radiation field of the PTW23344 ionization chamber in the range of 4.5 cm to 9 cm is 2.85 times that in the range of 9 cm to 13.5 cm whilst the average increase of the calibration coefficient of the absorbed dose to water in the range of 2.03 cm to 4.05 cm is 1.50 times that in the range of 4.05 cm to 6.08 cm in the radiation field.ConclusionsIt is necessary to make the radiation field completely cover the sensitive volume of the ionization chamber to achieve the condition of electron balance measurement, but not too large to cause too much scattering and damage.

The temperature of the working environment is one of the key factors in determining the properties of semiconductor detectors, and it affects the absolute accuracy and stability of the standard detector. In order to determine the temperature coefficient of CdTe detector used for X-rays detection, a precise temperature control system was designed. In this experiment, detectors and radiographic source were set inside a thermostat with temperature of 0~40°C, so that the temperature can be regulated for the test of the temperature coefficient of CdTe detector. Studies had shown that, with the increase of the temperature, the energy resolution and detection efficiency of the CdTe detector would deteriorate, and under 10°C the detectors have better performance with the 8 keV X-rays.