Solid Detectors Research Articles

Light Output Function and Pulse-Shape Discrimination Capability of p-Terphenyl Organic Scintillator in Wide Neutron Energy Range of 1.1 to 19 MeV

In this work, we studied the light-output properties, efficiency function, as well as the pulse-shape discrimination (PSD) capability of p-Terphenyl scintillator. The selected solid cylindrical scintillation detector has a thickness of 45 mm and a diameter of 45 mm. Recently presented studies of light-output functions have only been measured for low-neutron energies. Our motivation has been to determine the light output function for p-Terphenyl scintillator more accurately over a wider neutron energy range. The measurements have been carried out with mono-energetic neutron beams in the wide energy range from 1.1 to 19 MeV. The neutron–gamma spectrometric system which we developed has been used for the measurement. The input analog signal from the detector was digitized with a fast 12-bits analog to digital converter with a sampling frequency of 1 GHz. Measured data from the detector are processed into the gamma and neutron spectra. The accurate light output function for the p-Therphenyl scintillator has been calculated. The pulse-shape discrimination capability, as well as the detection efficiency, of a p-Terphenyl scintillator are lower in comparison with a NE-213 equivalent detector.

Theoretical analysis of neutron spectra measurement with SiC detectors using a machine learning technique

Detecting neutrons is crucial for various nuclear applications. Currently, there exists a technology gap in detecting fast neutrons under high-flux conditions, primarily due to some limitations solid detectors face in supporting high flux. Addressing these challenges requires a balanced approach that combines a detector capable of providing exploitable signals with an effective method for reconstructing the neutron spectrum. This work explores the potential of utilizing machine learning techniques to address this gap by determining neutron spectra using SiC detectors. The machine learning algorithm described in this paper has been tested on measured spectra stored in the IAEA Compendium database. The outcomes of this theoretical study demonstrate the feasibility of the proposed approach in determining neutron spectra from various neutron sources. However, experimental validation is necessary to fully validate the methodology and ensure its applicability in practical settings.

Performance of a coarsely pixelated LAPPD photosensor for the SoLID gas Cherenkov detectors

The SoLID spectrometer's gas Cherenkov counters require photosensors that operate in a high luminosity and high background environment. The reference design features arrays of 9 or 16 tiled multi-anode photomultipliers (MaPMTs), distributed across 32 sectors, to serve the light-gas and heavy-gas Cherenkov counters, respectively. To assess the viability of a pixelated INCOM Large Area Picosecond Photodetector (LAPPDTM) as an alternative photosensor to replace MaPMT arrays in either detector, we evaluated its performance under realistic SoLID running conditions in Hall C at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The results of this test confirmed that the coarse-pixelated (2.5 × 2.5 cm2 pixel size) LAPPD is capable of handling the total projected signal and background rates of the three pillar SoLID experiments. The tested photosensor detected Cherenkov signals with the capability of separating single-electron events from pair production events while rejecting background. Although the design was not aimed at ring-imaging Cherenkov detectors, Cherenkov disk images were captured in two different gas radiators. Through a direct comparison with a GEANT4 simulation, we confirmed the experimental performance of the LAPPD.

Theoretical design of a solid scintillation detector for tritium surface contamination measurement based on CaF2(Eu) sheet and self-coincidence technology of MCP-PMT

Measurement of tritium surface contamination is important for tritium related facilities, especially for fusion devices. A novel detector has been designed for tritium surface contamination measurements based on CaF2(Eu) sheet and Microchannel plate photomultiplier tube (MCP-PMT). Self-coincidence technology has been introduced to obtain lower detection limit by diminishing the background noise caused by γ-rays and hot electrons. Performance of the detector was optimized by specifying the key parameters including the distance of the scintillator and sample, the thickness of light guide, the number of annular electrodes et al., using Monte Carlo method. Results indicate that detection efficiency of 49.4 % and the response deviations at different positions less than 0.5 % could be achieved. The detection limit of tritium under the simulation conditions is 0.09 Bq/cm2 and 0.03 Bq/cm2 when the counting time is 10 s and 60 s, respectively.

SiC Detector Thickness Optimization for Enhanced Response Variability

Neutron spectroscopy is a crucial point in several nuclear applications. Accurately measuring fast neutron energy distributions in high-flux conditions reveals a significant technology gap, hindering the acquisition of precise energy fluence distributions. This project investigates the potential of machine learning to bridge this gap, focusing on neutron energies from 100 keV to 20 MeV and fluence rates from 1010 n/cm2s to 1012 n/cm2s using solid detectors such as Silicon Carbide (SiC) and Chemical Vapor Deposition (CVD) diamonds. This paper details the simulation design phase of our project, emphasizing the exploration of optimal SiC solid detector thickness to introduce crucial variability for machine learning training.

INVESTIGATION OF CENTERING PROBLEM IN THE CADMIUM ZINC TELLURIDE (CZT) CARDIAC CAMERA

Introduction: Cadmium Zinc Telluride (CZT) Cardiac Cameras are a special SPECT cameras with solid state cadmium zinc telluride detectors. This diagnostic method applied in the evaluation of coronary artery disease is well designed for myocardial perfusion scintigraphy. Aim: CZT cardiac cameras have limited detector area. In patients who are morbidly obese or whose heart is not in its normal location in the body, the center of the heart and the isocenter of the device do not coincide. It is aim to investigate how these conditions affect the imaging performance of the CZT cardiac camera. Methods: A homogeneous and spherical ball with a diameter of 4 cm was used for the research. To be able to measure away from the center a wooden phantom with 8 cavities and a total length of 32 cm was designed. The center as reference point has been determined by matching the center of the device with the center of the sphere. For the next imaging, the image were taken by placing the spherical ball in the other cavities, respectively, without changing the center. Results: According to the results obtained, farther from the center, deviations from sphericity and differences in dose distribution were observed. Counts decreased by 1.5% in the 2nd position and 16% in the 3rd position relative to the center in the X-axis. A disaster area has been formed and the image area has been exited from the 4th imaging. Conclusion: It is very important to center the patient as much as possible, otherwise the doctor will misdiagnose.

Determine the hazards of radioactive elements and radon gas manufacturing processes in an Egyptian fertilizer factory

This study investigated the levels of radioactivity in soil surrounding a phosphate fertilizer factory in Egypt, aiming to assess potential risks to the population exposed to radiation. Concentrations of 238U, 226Ra, 232Th, and 40K were measured in soil samples collected from two subsites: one near the factory (subsite 1) and another further away (subsite 2). Two different systems were used for measuring radioactivity, a high-purity gamma ray spectroscopy system with an HPGe detector for gamma-emitting isotopes and a CR-39 solid nuclear track detector for alpha-emitting radon gas. Subsite 1, located close to the factory, displayed significantly elevated levels of 226Ra compared to global background levels (514 and 456 Bq/kg vs. 35 Bq/kg). Additionally, the concentrations of 238U (241.06 Bq/kg vs. global average 35 Bq/kg), 232Th (16.15 Bq/kg vs. global average 30 Bq/kg), and 40K (146.36 Bq/kg vs. global average 400 Bq/kg) were all above global averages. Furthermore, a high concentration of radon gas (337.06 μSv/y) was measured at subsite 1. The strong positive correlation observed between 226Ra and 238U (0.96256) provides further evidence of potentially elevated radioactivity levels near the factory. In contrast, subsite 2, situated farther from the factory, exhibited natural radioactive background levels within international limits. Quantitative analysis revealed that gamma ray absorbed doses for 226Ra and 232Th exceeded global averages in some samples. Specifically, 226Ra doses ranged from 7.8 to 46.26 ppm (exceeding the 20 ppm global average in some cases), and 232Th doses ranged from 1.98 to 9.14 ppm (exceeding the 10 ppm global average in some cases). The concentration of 40K, however, remained within the global range (0.07%–0.69 %). The observed imbalances in the ratios of Th/U (0.17–0.24 Bq/kg and 0.73–0.24 ppm) and U/Ra (0.81–0.73 Bq/kg and 0.73–0.17 ppm), both of which are significantly lower than their respective global averages of 4 and 2.4, point towards the presence of fertilizer-derived contamination. This conclusion is further supported by the high phosphate concentrations detected in the samples. Overall, this study suggests that radioactive contamination near the phosphate fertilizer factory significantly exceeds global background levels and international limits in some cases. This raises concerns about potential risks posed to surrounding agricultural land and crops.

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New neutrino–nucleus interaction cross-section measurements are required to improve nuclear models sufficiently for future long baseline neutrino experiments to meet their sensitivity goals. A time projection chamber (TPC) filled with a high-pressure gas is a promising detector to characterise the neutrino sources used for such experiments. A gas-filled TPC is ideal for measuring low-energy particles, which travel further in gas than in solid or liquid detectors and using high-pressure increases the target density, resulting in more neutrino interactions. We examine the suitability of multiwire proportional chambers (MWPCs) from the ALICE TPC for use as the readout chambers of a high-pressure gas TPC. These chambers were previously operated at atmospheric pressure. We report the successful operation of an ALICE TPC outer readout chamber (OROC) at pressures up to 4.2 bar absolute (barA) with Ar-CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {Ar-CH}_4$$\\end{document} mixtures with a CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CH}_{4}$$\\end{document} content between 2.8 and 5.0%, and so far up to 4 bar absolute with Ar-CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {Ar-CO}}_2$$\\end{document} (90-10). The charge gain of the OROC was measured with signals induced by an 55Fe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{55}\ ext {Fe}$$\\end{document} source. 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In Ar-CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {Ar-CO}}_2$$\\end{document} with 10% CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CO}_{2}$$\\end{document} at 4 barA, a gain of (4.2±0.1)·103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(4.2\\pm 0.1)\\cdot 10^{3}$$\\end{document} was observed with anode voltage 2975V\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${2975}\\,\\hbox {V}$$\\end{document}. We extrapolate that at 10 barA, an interesting pressure for future neutrino experiments, a gain of 5000 in Ar-CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext {Ar-CO}}_2$$\\end{document} with 10% CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CO}_{2}$$\\end{document} (10,000 in Ar-CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {Ar-CH}_4$$\\end{document} with ∼4%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\!{4}{\\%}$$\\end{document}CH4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {CH}_{4}$$\\end{document}) may be achieved with anode voltage of 4.6kV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${4.6}\\,\\hbox {kV}$$\\end{document} (∼3.6kV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim \\!{3.6}\\,\\hbox {kV}$$\\end{document}).

Superconducting transition edge bolometer for high-flux neutron detection

Needs for neutron detection and monitoring in high neutron flux environments are increasing in several different fields. A completely solid-state, current mode bolometric detector is constructed as a solid substrate transition edge sensor based on a high-Tc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_c$$\\end{document} superconducting meander. The detector consists of four individual pixels of which three pixels include 10B4C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{10}{\\hbox {B}}_{4}\\hbox {C}}$$\\end{document} neutron absorption layers. The absorbed energy per neutron absorption reaction is modelled and compared to experimental data. The response of the tested detector is directly correlated to a cold neutron beam with a flux of 1.8×108n/cm2/s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${1.8\ imes 10^{8}}\\,{\\hbox {n}/{\\hbox {cm}}^2/\\hbox {s}}$$\\end{document} modulated by a slit. The signal is found to be an order of magnitude higher than the thermal background. The dynamics described by the temporal saturation constants is governed by a modulation frequency less than 1Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${1}\\hbox { Hz}$$\\end{document}. The thermal response is dynamic and never fully saturates for 50s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${50}\\hbox { s}$$\\end{document} exposures. The efficiency for this proof-of-principle design is 1–2%. Possibilities for optimization are identified, that will increase the efficiency to become comparable to existing solid boron-10 detectors. The existing detectors with event-based read-out have limited functionality in high flux environments. The superconducting bolometer described in this work using current-mode readout will pave the way for high flux applications.

Half-life of the nuclear cosmochronometer 176Lu measured with a windowless 4π solid angle scintillation detector

The 176Lu-176Hf nuclear decay is a powerful tool to measure the age of astrophysical and geological events and has been used as a “cosmochronometer”. However, the half-life values of 176Lu measured with various experiments differ significantly. Furthermore, the half-life values evaluated from Lu-Hf isochrons in meteorites and terrestrial rocks with known ages show two different values. Here we report half-life measurements using a method that is almost independent of various uncertainties. To the best of our knowledge this is the most accurate value of 176Lu half-life. We measure the total energy released from 176Lu decay using a windowless 4π solid angle detector based upon bismuth germanate (BGO) scintillation crystals, where a natural Lu sample is located inside of the detector. The measured half-life of (3.719 ± 0.007) × 1010 yr corresponding to a decay constant of (1.864 ± 0.003) × 10−11 yr−1 is consistent with that obtained from the analysis of terrestrial rocks within the uncertainty.

Characteristics of Indoor and Soil Gas Radon, and Discussion on High Radon Potential in Urumqi, Xinjiang, NW China

Urumqi City, located in the northwest of China, is a city with a high indoor radon concentration in a nationwide indoor radon survey in China. This study focuses on the assessment of the indoor radon level and its distribution in this city. Indoor radon measurement using RAD7 and solid nuclear track detector (SSNTD), soil gas radon measured by RAD7, and the determination of the specific activity of uranium and radium in soil samples by a high pure germanium spectrometer were performed from 2021 to 2023. The results reveal a wide range of indoor radon concentrations in Urumqi, with anomalies above 400 Bq/m3 in some dwellings. The arithmetical and geometric mean values of indoor radon concentration are 80 ± 77 Bq/m3 and 58 Bq/m3, respectively. The geometric mean value of radon measured by SSNTD is 101 Bq/m3. The distribution of areas with a high indoor radon concentration is spatially consistent with deep and large active faults or overlapping and intersection zones of multiple groups of faults. It is recommended to conduct a more comprehensive investigation and research into the elevated radon potential and radioactivity associated with building materials.

Cryogenic phonon-detector model with solid argon for detecting dark matter* *This work is supported by the National Key Research and Development Program of China (2017YFA0402203) and the National Natural Science Foundation of China (12075161)

Over the past few years, phonon detectors have emerged as a prevailing technology for detecting low-mass dark matter due to their low thresholds and high resolution. These detectors, which employ either dual-phase detectors combining phonon-light or phonon-electron interactions, have significantly advanced direct dark matter detection efforts. Argon, as a low-background and high-reserve detection medium, has also played a crucial role in this field. Both liquid-argon single-phase detectors and gas-liquid two-phase time projection chambers (TPCs) have contributed substantially to the direct detection of high-mass dark matter. By integrating these distinct detector types, the upper limits of the corresponding mass cross-section in dark matter detection can be lowered. We propose a phonon detector utilizing solid argon as the absorber, which combines the advantages of both aforementioned detector types. However, due to the requirement for an ultra-low temperature environment in the tens of millikelvin (mK) range, experimental investigations of solid argon phonon detector performance are currently constrained by technical limitations. Therefore, the performance analysis of the solid argon phonon detector presented in this study is only based on sapphire phonon detectors. Although there may be discrepancies between this approximation and the actual performance, the intrinsic characteristics of phonon detectors permit a qualitative evaluation of the solid argon phonon detector's potential capabilities.

Can we use heavy nuclei to detect relic neutrinos?

Recent analysis of the viability of solid state-based relic neutrino detectors has revealed the fundamental necessity for the use of heavy, A>100, beta -decayers as neutrino targets. Of all heavy isotopes, and stand out for their sufficiently low decay energies, reasonable half-life times and stable daughter nuclei. However, the crucial bit of information, that is the soft neutrino capture cross-section is missing for both isotopes. The main reason for that is a particular type of beta -decay, which precludes a simple link between the isotope’s half-life time and the neutrino capture rate. In light of the necessity for a reliable estimate of the capture rate – unimpeded by potentially devastating theoretical uncertainties – prior to using the isotope in a full-scale experiment, we propose an experimental method to bypass this difficulty and obtain the capture cross-section of a soft neutrino by a given isotope from the isotope’s beta -spectrum.

Optimization, Validation and Application of Quantitative Method for the Determination of Acrylamide in Potato Chips Samples in Yemen Using GC-NPD

Over the last two decades, numerous analytical methods for determining acrylamide concentration in a wide range of food products have been developed. Some studies focused on the methods of extracting acrylamide from complex food matrices. In the present study, solid Phase Extraction (SPE) and Gas Chromatography-Nitrogen Phosphorus Detector (GC-NPD) analysis were employed to develop a simple and cost-effective acrylamide determination method. Method validation and optimization steps were carried out and used to determine acrylamide concentrations in potato chips purchased from Yemeni markets. In the concentration range of 0.1- 5 ppm, the validated method demonstrated good sensitivity within a 0.012 ppm limit of detection (LOD) and an excellent linearity of 0.996 correlation coefficient. Eighteen samples of potato chips purchased from local markets in Sana'a, Yemen, were analyzed using this method. Three of the 18 samples of interest contained various acrylamide concentration levels of 879.4, 795.6, and 754.7 ppb. These were higher than the EU Commission's indicative value for the acrylamide in potato chips (750 ppb). As a result, the optimized GC-NPD protocol proved to be useful for the acrylamide analysis, paving the way for the development of an acrylamide quantification prescreening tool in the food industry.

Construction of hierarchically porous metal-organic framework HP-UiO-66-30% for sensitive determination of benzoylurea insecticides

Due to widespread application of benzoylurea insecticides (BUs) and its persistence in environment, the effective capture of benzoylurea insecticides residues in environment is an important issue of environmental safety monitoring. To obtain excellent adsorption performance, creating defective structure in metal-organic frameworks (MOFs) can be employed as the method for adjusting its properties. Zirconium(Ⅳ)-based MOF termed as UiO-66-30% was constructed with 2-aminoterephthalic acid (NH2-BDC) and terephthalic acid (H2BDC) as building blocks. After calcination and removal of thermal-sensitive ligand (NH2-BDC), hierarchically porous UiO-66-30% (HP-UiO-66-30%) with multistage pore structure and good stability was obtained. The unique structure of HP-UiO-66-30% endowed it to achieve instantaneous equilibrium (within 2 min) when it was used as a dispersed solid phase extraction (d-SPE) adsorbent to extract BUs from environmental samples, greatly reducing the operation time. A wide linear range (0.05–200 ng mL−1), good linearity (R2 ≥ 0.9980), low detection limits (0.01–0.03 ng mL−1) and quantification limits (0.05–0.1 ng mL−1) were obtained for BUs. In addition, the HP-UiO-66-30% material possessed the good reusability and the adsorption capacity did not change significantly over 16 adsorption-desorption cycles. Finally, the established dispersed solid phase extraction-high performance liquid chromatography-diode array detector (d-SPE-HPLC-DAD) method was successfully applied to determination of BUs residues in environmental soil samples. The results demonstrated that HP-UiO-66-30% was an excellent sorbent for extraction BUs from environmental samples.

Radiotherapy delivery error detection with electronic portal imaging device (EPID)-based in vivo dosimetry.

Radiotherapy delivery error detection with electronic portal imaging device (EPID)-based in vivo dosimetry.

Comparison of morphological characteristics for alpha tracks in CR-39 using different radon monitors

CR-39 is a solid nuclear track detector that is commonly used for long-term passive radon monitoring. For a specific incident particle, etching condition and type of CR-39, the morphology of the nuclear tracks in CR-39 varies with the energy and angle of incident particles. This study systematically compares the performance of six different passive radon monitors from the perspective of nuclear track morphology using both theoretical calculations and experiments. Based on different shapes of exposure chambers for these monitors, different strategies for dealing with incident α particles can be observed, especially for those emitted from deposited progeny on the inner wall. These characteristics contribute to the strengths and weaknesses of each monitor in terms of efficiency, uncertainty, robustness in measurement, and consistency of track morphology. The results of this study revealed that the optimisation of the radon monitor should be multidirectional and situation-oriented. It was expected to be helpful to improve radon measurement using these monitors.

Preparation of Large Volume Solid Argon Crystal and Its Feasibility Test as a Scintillation Material

An important background to the liquid argon detectors is that they are caused by the diffusion of radioactive isotopes in a scintillator (liquid phase). This radioactive isotope is produced in argon’s surrounding devices, such as circulation pipelines and liquid argon containers. The solid argon as a scintillation material in the detector can inhibit the diffusion and drift of radioactive isotopes in a solid phase scintillator. Additionally, the structure of a solid argon detector is simple and reduces the total source of radioactive background. In the CDEX-300 detection system, solid argon could substitute for liquid argon as the veto detector, preventing radioactive isotopes drifting to the central main detector (HPGe detectors array) surface to reduce backgrounds. Therefore, solid argon has great potential in the experiments since it is especially helpful to get the lower background in a larger active volume than liquid argon required in those low background detection experiments. This work introduces the preparation process and device of the large volume transparent crystalline argon, the acquisition of scintillation light, and the pulse amplitude spectrum of 137Cs obtained from a prototype detector of transparent solid argon crystal. The results show that the scheme proposed in this study can successfully produce a large volume transparent crystalline argon detector, the scintillation light signals can be effectively obtained from the solid argon scintillator, and the corresponding pulse amplitude spectrum is given. This work indicates that it is feasible to develop a solid argon crystal scintillation detector by using our approach.

Investigation of thermal neutron detection efficiency of Boron Carbide converter material using GEANT4 simulation for different types of detector configurations

A lot of advancement in the field of semiconductors has made it possible to design a solid state neutron detector. They are small in size and compact, have economical bulk fabrications, require low power for their operation. Hence it can act as a plausible alternative to traditional neutron detector such as gas filled and scintillation detectors. It has been observed that many factors like the choice of converter material, LLD settings and geometrical configurations have an impact on the thermal neutron detection efficiency of solid state neutron detector design. Therefore in the present research work, a systematic GEANT4 simulation have been performed on estimating the simulated thermal neutron detection efficiency (η) for five different solid state detector geometrical configurations design with Boron Carbide (10B4C) as a converter material. These detectors geometry configurations designs are planar, rectangular parallel trenches, cylindrical perforation, stack and spherical (single and multi-layer). The objective of the simulations was to obtain critical geometrical features for which the efficiency reaches the maximum value, of the given detector configurations. The influence of the different enrichment levels of 10B (20% to 80%) in Boron Carbide and different Low-Level Discriminator (LLD) value setting (from 100 keV to 700 keV) on the simulated thermal neutron detection efficiency was also investigated. Finally, the simulated multi channel analyzer spectra or in other words histoplots were obtained for all the detector configurations.

In orbit testing of SOLID debris detector

The number of artificial objects in space increases due to past and present space activities. To analyse the quantity of the small (diameter >100 μm up to cm) space debris and meteoroids, an innovative in-situ impact detection method has been developed at DLR (German Aerospace Center) in Bremen, Germany. The method Solar panel-based Impact Detector “SOLID” uses solar panels for impact detection. Since solar panels provide large detection areas and exist on nearly all satellites, this method enables for the collection of large amounts of data in different orbits. An impacting object generates a permanent damage on a panel. The damage can be determined during analysis scan as well as confirmed or refuted in the frame of subsequent scans of the panels. Those properties of the sensor system can significantly improve the amount as well as the quality of measurement data to be used for environmental model validation. The SOLID method was successfully verified on ground by Hypervelocity Impact (HVI) tests at Fraunhofer EMI, Freiburg, Germany. The ability of the detection method SOLID for impact detection of space debris and meteoroids was clearly demonstrated on ground. Since July 2017, the SOLID sensor system is placed in a 600 km Sun-synchronous orbit on the microsatellite mission TechnoSat of Technische Universität Berlin (TUB). Four solar panels equipped with SOLID technology are installed on the satellite for in-orbit testing and environmental exploration. The total detection area of all panels is about 0.0755 m2. The system was designed to detect space debris or meteoroid objects with a diameter larger than 100 μm. In total 15,570,047 scans were performed over the four years in space. By means of measurement data changes were identified on one panel. However, so far, the telemetry data shows no clear evidence for an impact.