Solid-state Detectors Research Articles

Evaluation of the radiation emission of radon gas from various building materials

Soil and rocks contain radium, which decays to produce radon gas. Given its potential health risks, particularly its association with lung cancer, this study aimed to determine radon levels in different building materials sourced from the Jazan region of Saudi Arabia using a CR-39 solid-state detector. The results indicated that the average radon concentration for all building materials was 291 Bq/m3. Granite showed the highest radon level, with an average concentration of 506 Bq/m3. These results highlight the wide variation in radon content between different building materials, confirming the tendency of granite to retain and release radon gas. Granite recorded the highest radiation dose value, averaging 10.71 μSv/yr. Furthermore, we measured the uranium levels and found them to be within the safe limit. These results recommend granite use primarily in outdoor areas where ventilation can mitigate potential health risks associated with radon exposure. Conversely, its use indoors should be limited to reduce the potential for radon buildup within buildings. Comparison with different studies of radium concentrations in building materials reveals significant differences, particularly high levels in granite, and underscores the need for local assessments to inform safety guidelines and promote public health. Overall, this study underscores the importance of evaluating building materials for their radon emission potential to ensure safer living environments and inform construction practices in areas with similar geological characteristics.

Simulation excess lifetime lung cancer risk due to indoor radon exposure in Eastern Iran - Monte Carlo Simulation method

Indoor environmental radiation, primarily from natural radionuclides, can pose a significant health risk due to continuous exposure. This study investigated the excess lifetime cancer risk (ELCR) associated with indoor radon exposure in Gonabad, eastern Iran, using the Monte Carlo Simulation (MCS) method. CR-39 solid-state nuclear track detectors (SSNTD) were employed to measure radon levels in 50 samples across various geographical directions. The highest ELCR was observed at location S23, with a value of 64 Bq/m³, while the lowest ELCR was found at location S25, with a value of 1 Bq/m³. Further analysis using Duncan's multiple comparison tests revealed significant differences in radon concentration among geographical groups (P ≤ 0.05). MCS analysis indicated that a majority of the population had a relatively low ELCR (approximately 0.001). Notably, individuals aged 65 and over exhibited a higher ELCR from radon exposure, while smokers displayed an increased tendency toward higher ELCR. Additionally, males demonstrated a greater risk compared to females. The cumulative probability distribution showed that a significant proportion of individuals had a relatively low risk of cancer (ELCR ≃ 0.001) from radon exposure. The interquartile range (IQR: 0.0005–0.0015) suggests that most individuals experienced a relatively low cancer risk from radon exposure. This study provides crucial information for developing targeted public health strategies to mitigate the risks of radionuclide exposure in Gonabad City, ultimately improving the well-being of its residents.

Assessment of photon and proton-induced activation in particles accelerators.

Nuclear activation affects all operating, future, or dismantled particle accelerators used in various fields, from medical applications to industrial applications. This work is concerned with the study of the radioactivity induced in various materials (Sc, Cu, Tb, Ta, W, Au) irradiated by hard Bremsstrahlung photons from an electron beam and by secondary neutrons induced by a proton beam. In both cases, the primary beam features an 18 MeV kinetic energy. We have performed Monte Carlo simulations with MCNP, GEANT4, FLUKA, and PHITS, coupled with the analytical codes CINDER'90 or FISPACT-II, to estimate the threshold reaction rates and the induced radioactivity in the samples. We compared the simulations with experimental activation measurements performed by high-resolution gamma spectrometry at a decommissioned medical LINAC and around the CYRCé cyclotron. We also used CR-39 solid-state nuclear track detectors to characterize the thermal and fast neutron components of the secondary fields.

Deep learning-based alpha particles spectroscopy with solid-state nuclear track detector CR-39

A novel approach for alpha particles energy spectroscopy utilizing a sophisticated deep learning machine learning algorithm is introduced. The approach we employ classifies the alpha particles trajectories on a CR-39 detector into six discrete energy levels: 0.5 MeV, 1.5 MeV, 2.5 MeV, 3.5 MeV, 4.5 MeV, and 5.4 MeV. Some 57 different CR-39 detectors were exposed to alpha particles of the stated energy levels using a241Am source. The dosimeters were then subjected to etching and imaging utilizing a Landauer Neutrak© system. A self-developed computer vision method was used to separate the energy-tagged alpha tracks from the CR-39 images. These tracks images were then inputted into an artificial neural network (ANN) algorithm for training. After completing the training, a test dataset was run to assess the algorithm's performance. An average accuracy rate exceeding 98% was attained across the six energy levels.This algorithm has the potential to enhance the precision of alpha particle dosimetry. Furthermore, once generalized to a continuous energy spectrum, as well as for other types of particles such as protons, this algorithm is anticipated to prove highly beneficial for analyzing the outcomes of various laser-driven high-energy particle experiments in general, and specifically for fusion experiments.

Impact of the Abrasive Solution Heating Process With Different Techniques on the Etching Parameters for the SSNTD (CN-85)

Abstract The presented work aims to compare and analyze the impact of the abrasive solution heating process using three different techniques on the etching parameters for the solid-state nuclear track detector (SSNTD) (CN-85). Water bath technique (WB) is using water as a conduction medium of heat transfer to heat the etching solution. The thermal oven technique (TO) is using air as a convection heat transfer medium to heat the etching solution. Finally, the micro-wave technique (MW) as electromagnetic radiation no need for a medium to heat the etching solution. That comparison will be achieved at different irradiation times to an Americium-241 source (241Am) of 5.486 MeV energy and 10 μCi activity as an alpha particle's emitter. Two irradiation times 10 s and 20 s are applied. Small pieces of CN-85 detectors (1 × 1) cm2 were used. CN-85 detector parameters of the etching process, with the three applying techniques (WB, TO, and MW), are estimated and compared. The obtained results from the three techniques are compared. The etching process time is developed to nearly 5 min for MW with heating by radiation mechanism compared to 25–35 min for etching techniques (WB and TO) with heating by conduction and convection mechanisms, respectively. The efficiency of MW technique with range of from 70% to 75% are five times greater than that for WB and TO techniques.

Dosimetry for FLASH and other non-standard radiotherapy sources

We review current dosimetry practices for non-standard radiotherapy sources. We classify radiotherapy sources as established, variations of established, or novel. Our review concentrates on novel sources including ultra-high dose-rate (FLASH) sources and some that have yet to be used for clinical radiotherapy. Factors which differentiate non-standard sources include dose-rate, temporal pulse structure, spatial fractionation, focusing, the presence of magnetic fields, and energy range. For the most part we exclude techniques which use materials inside the tumor to modify the dose. Dosimetry techniques include ionization chambers, film, alanine, calorimetry, and solid-state detectors. We review dosimetry only, neglecting other issues such as beam monitoring, patient delivery systems and treatment planning.

4D-tracking with digital SiPMs

Silicon Photomultipliers (SiPMs) are the state-of-the-art technology in single-photon detection with solid-state detectors. Single Photon Avalanche Diodes (SPADs), the key element of SiPMs, can now be manufactured in CMOS processes, facilitating the integration of a SPAD array into custom monolithic ASICs. This allows implementing features such as signal digitization, masking, full hit-map readout, noise suppression, and photon counting in a monolithic CMOS chip. The complexity of the off-chip readout chain is thereby reduced.These new features allow new applications for digital SiPMs, such as 4D-tracking of charged particles, where spatial resolutions of the order of 10µm and timestamping with time resolutions of a few tens of ps are required.A prototype of a digital SiPM was designed at DESY using the LFoundry 150nm CMOS technology. Various studies were carried out in the laboratory and at the DESY II test-beam facility to evaluate the sensor performance in Minimum Ionizing Particles (MIPs) detection. The direct detection of charged particles was investigated for bare prototypes and assemblies coupling dSiPMs and thin LYSO crystals. Spatial resolution ∼20µm and a full-system time resolution of ∼50ps are measured using bare dSiPMs in direct MIP detection. Efficiency >99.5%, low noise rate and time resolution <1ns can be reached with the thin radiator coupling.

Calibration-free infrared absorption spectroscopy using cantilever-enhanced photoacoustic detection of the optical power

We report on sensitive tunable laser absorption spectroscopy using a multipass gas cell and a solid-state photoacoustic optical power detector. Unlike photoacoustic spectroscopy (PAS), this method readily allows a low gas pressure for high spectral selectivity and a free gas flow for continuous measurements. Our photoacoustic optical power detector has a large linear dynamic range and can be used at almost any optical wavelength, including the middle infrared and THz regions that are challenging to cover with traditional optical detectors. Furthermore, our approach allows for compensation of laser power drifts with a single detector. As a proof of concept, we have measured very weak CO2 absorption lines at 9.2 µm wavelength and achieved a normalized noise equivalent absorption (NNEA) of 2.35·10−9 Wcm−1Hz−1/2 with a low-power quantum cascade laser. The absolute value of the gas absorption coefficient is obtained directly from the Beer-Lambert law, making the technique calibration-free.

Radionuclides distribution in soils and radon level assessment in dwellings of Mungo and Nkam Divisions, Cameroon.

Radionuclide and radon levels have been investigated in soil samples and residential environments within the Mungo and Nkam Divisions of the Littoral Region. These analyses employed gamma spectrometry facilitated by a NaI (Tl) detector for soil samples, yielding average activity concentrations of 226Ra, 232Th, and 40K at 23.8, 72, and 105Bqkg-1, respectively. Various radiological parameters were calculated to evaluate radiological hazards. Additionally, the indoor radon concentrations were quantified utilizing the CR-39 solid-state nuclear track detector (Radtrack), revealing an average concentration of 25Bqm-3 and an associated inhalation dose of 0.66mSv y-1. Risk assessments for lung cancer attributable to indoor radon exposure incorporated models such as the Harley model. An observed moderate correlation between indoor radon levels and external 226Ra concentrations implies that radon intrusion indoors might be substantially influenced by the 226Ra present in the subjacent soil, considering the construction of residential structures directly upon these terrains.

Estimation of radon annual effective dose and excess lung cancer risk for the residents of KufrKhal, Jordan

This study aims to measure radon gas concentration, calculate the annual effective dose, and calculate excess lung cancer risk in KufrKhal-Jerash north of Jordan. Radon is a radioactive gas located everywhere and contributes more than 40% of people’s total dose from natural radiation. The Risk concerns have resulted from the increase in mortality due to lung cancer in KufrKhal. About 117 well-calibrated dosimeters were among the study area’s districts (Hill 1, Hill 2, Hill 3, and village center). Each dosimeter consists of a plastic cup with known dimensions and a piece of solid state nuclear track detector (SSNTD) type CR-39 fixed in the inner bottom of the cup. After 90 days, the retrieved detectors were chemically etched, and the track density (tracks.cm−2) was determined. The results showed that the average radon concentrations drastically varied between the districts of KufrKhal (17.1–128.8 Bqm−3). However, the mean radon values in different districts are closely related (64.4–75.5 Bq.m−3). The lowest concentration (17.1 Bqm−3) was found in the Hill 1 district, and the highest value (128.8 Bqm−3) was found in the village center. However, the overall radon concentration in KufrKhal was approximately 69.2 Bqm−3. This value is within the range of the national average level (43.2 – 77.4 Bq.m−3) and way below the national action level (200 Bq.m−3). Furthermore, the corresponding values of the annual effective dose (AED) and the excess lung cancer risk (ELCR) for dwellers in this village were calculated to be 1.8 mSv.y−1 and 0.2%, respectively. These values, according to Jordan’s national regulations are acceptable.

Nonlinear Calibration and Temperature Sensitivity of Makrofol Solid-State Nuclear Track Detectors for Radon Measurement

A key characteristic of a solid-state nuclear track detector (SSNTD) is that as more alpha tracks accumulate on the detector, the likelihood of track overlap will increase, making it difficult to distinguish individual events. This article presents the calibration of an in-house SSNTD using a Makrofol polycarbonate detector and electrochemical etching. The calibration employs a nonlinear log-logistic quantile function, which is nearly linear at low exposures but accounts for the reduced efficiency at high exposures due to overlapping alpha tracks. The function can be fitted to calibration measurements very accurately, eliminating systematic errors previously associated with the method at certain radon exposures. This article explores the uncertainties and detection limits associated with the calibration and outlines methods for their evaluation. Additionally, it includes a preliminary discussion on the method’s sensitivity to temperature.

Assessment of tracheobronchial and lung dose due to radon and thoron inhalation.

The main sources of natural background radiation are radon, thoron and their progeny, which may cause health risks to humans. Keeping in mind the importance of the subject, three samples each from 10 selected residential areas, including the centre of Babylon Governorate, Iraq, and its districts, were collected. Concentration of radon and thoron was measured using solid-state track detectors (CR-39). The arithmetic means of the concentration of radon and thoron were 47.367±19.56 and 133.246±16.585 Bqm-3, respectively; these values are considered safe when compared with the upper reference level of 200-600 Bqm-3 recommended by the International Commission for Radiological Protection (ICRP). The value of the inhalation equivalent dose from radon gas discovered in these areas with rate 37.893 nSv is less than the value of the global average of 1.15 mSv. This indicates that the risks related to inhalation of radon are low as the lung dose rate (DLung), tracheobronchial region (DT-B), annual effective dose (AED) and excess lifetime cancer risk (ELCR) is (1.894 nGyh-1, 22.736 nSv, 0.236 mSvy-1 and 0.835 x10-3), respectively. While the value of the inhalation equivalent dose (IED) from thoron as effective dose to lung DLung, AED and ELCR are equal to (0.133 nSv, 0.167 mSvy-1 and 0.587 x 10-3), respectively. To conclude, the rates in the study area are less than the ICRP recommended level of 3 mSv; therefore, the studied areas are safe from the health risks of inhalation of radon and thoron.

Coherent long-term average indoor radon concentration estimates obtained by electronic and solid state nuclear track detectors

Despite the rapid development of consumer-grade electronic radon monitors, their capabilities to assess long-term average radon concentrations are not systematically investigated. We present the results of a year-long measurement campaign in 32 dwellings and workplaces in two areas with typical and high radon concentrations in Bulgaria. A systematic comparison was made between electronic monitors and the gold standard — solid-state nuclear track detectors (SSNTDs). RadonEye Plus2 (RE) monitors were used, calibrated and metrologically tested at the three participating laboratories. Two SSNTD-based detectors were utilized: passive radon detectors (PRDs) developed by UKHSA, and CDs/DVDs, developed at SU. Two PRDs for quarterly radon measurements, a RE, a CD and a DVD were placed at each location. Additional old CDs/DVDs were collected for retrospective radon estimates. The results for the annual average radon concentrations, estimated by the four methods are presented. The average difference between the REs and PRDs estimate was 8% (median 4%), between the REs and CDs was 5% (median 0.4%) and between REs and DVDs was −10% (median −12%). The Z-score, representing the difference normalized to its uncertainty, in most cases fell within −1 and 1, indicating excellent agreement. The retrospective estimates also demonstrated excellent agreement with the other data. However, in some cases, small but statistically significant biases were identified between REs and SSNTDs or between different SSNTDs, requiring an inclusion of a reference instrument in future studies. Overall, the results imply that with sound metrological assurance, RadonEye Plus2 monitors can assess long-term average radon concentrations with sufficient accuracy.

Radiation protection in dental imaging: Evaluating the impact of the SABA thyroid shield during panoramic and cone beam computed tomography

BackgroundDental panoramic radiography (DPR) and cone beam computed tomography (CBCT) are an imaging modalities in dentistry. However, these procedures involve exposure to ionising radiation, raising concerns about radiation-induced thyroid damage. To mitigate these risks, thyroid shields have been introduced. This study aimed to evaluate the effectiveness of the SABA thyroid shield in reducing thyroid radiation exposure during DPR and CBCT scans. MethodAn experimental study to measure surface dose in the thyroid region during (DPR) and (CBCT) scans using an Anthropomorphic Phantom and a Solid-State Detector. The attenuation percentage was calculated between radiation surface doses with and without shielding. The significance of the Saba thyroid shield was calculated using a t-test. ResultsFor DPR scans, the average surface doses in the thyroid reduced significantly from 301.1 μGy (at 85 kVp) and 170.3 μGy (at 60 kVp) to 64.43 μGy and 12.94 μGy, respectively, when the Saba thyroid shield was used. For CBCT scans, the average surface doses in the thyroid decreased significantly from 814.43 μGy (for 11 × 13 cm2 field size) and 32.40 μGy (for 5 × 5 cm2 field size) to 62.91 μGy and 12.07 μGy, respectively, with the application of the Saba thyroid shield. The maximum attenuation percentages in the thyroid for the DPR and CBCT scans were 92.40% and 92.27%, respectively. Statistically significant differences between the surface dose reduction with the Saba shield and without it was observed in both DPR scans (p < 0.0000) and CBCT scans (p < 0.0003). ConclusionThe study demonstrates that Saba thyroid shields effectively reduce doses in the thyroid region during dental DPR and CBCT scans. The dose reduction depends on tube voltage for DPR scans, field size, and its position for CBCT scans. Findings highlight the importance of using Saba thyroid shields to minimise radiation exposure and protect the thyroid gland during dental scans.

Registration of activity of a single molecule of horseradish peroxidase using a detector based on a solid-state nanopore.

This work demonstrates the use of a solid-state nanopore detector to monitor the activity of a single molecule of a model enzyme, horseradish peroxidase (HRP). This detector includes a measuring cell, which is divided into cis- and trans- chambers by a silicon nitride chip (SiN structure) with a nanopore of 5 nm in diameter. To entrap a single HRP molecule into the nanopore, an electrode had been placed into the cis-chamber; HRP solution was added into this chamber after application of a negative voltage. The reaction of the HRP substrate, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), oxidation by the enzyme molecule was performed in the presence of hydrogen peroxide. During this reaction, the functioning of a single HRP molecule, entrapped in the nanopore, was monitored by recording the time dependence of the ion current flowing through the nanopore. The approach proposed in our work is applicable for further studies of functioning of various enzymes at the level of single molecules, and this is an important step in the development of single-molecule enzymology.

250 μm Thick Detectors for Neutron Detection: Design, Electrical Characteristics, and Detector Performances

Solid State Detectors (SSD) are crucial for fast neutron detection and spectroscopy in tokamaks due to their solid structure, neutron-gamma discrimination, and magnetic field resistance. They provide high energy resolutions without external conversion stages, enabling compact array installations in the harsh environment of a tokamak. Research comparing diamond and 4H-SiC detectors highlights thickness as a key efficiency factor. A 250 μm SiC epilayer with low doping, grown using a high-growth-rate process, exhibits sharp interfaces and minimal defects, essential for neutron detectors. The study evaluates detector designs, and performance using a 4H-SiC substrate. Various detector designs, such as Schottky diodes and p/n diodes, are assessed via I-V and C-V measurements, addressing high depletion voltage challenges. Preliminary neutron irradiation tests validate detector functionality, energy resolution and confirming detector reliability.

Methodology of integrated measurements with radon diffusion chamber

Calibration of Solid-State Nuclear Track Detectors - SSNTD in the diffusion chamber in most cases assumes a constant radon concentration outside the diffusion chamber and a steady state. Although this has been proven to be a valid approximation in most cases, the fact is that the radon concentration outside the chamber is not constant. In this way, the detectors are calibrated to measure the mean radon concentration. For this reason, there is doubt if the time-dependent concentration in dwellings results in the same number of tracks on the detector as the time-averaged radon concentration for the same exposure period. To obtain an answer, time-dependent and steady-state diffusion equations for radon and its progeny were solved. Then the number of tracks on the detector was calculated for these two cases and compared. For that goal, software for solving the time-dependent diffusion equation for time-varying external radon concentration was developed. Results show that concentrations measured using a diffusion chamber are the real concentrations at the measuring site. However, it was also found that the validity of results is not a universal property, as shown in the current paper. In some cases, results can be wrong. For some extreme conditions when diffusion coefficients are disrupted calibration using stationary conditions model will lead to incorrect results of real measurements in experiments where ambiental concentration is time-varying.

PNIPAM microgel coatings of LiF crystal radiation detectors

Thin films of poly(N-isopropylacrylamide) (PNIPAM) microgels have recently attracted significant attention as promising candidates for creating switchable interfaces in biomedical and biotechnological applications. In this study, microgel films are proposed as smart coatings for photoluminescent solid-state radiation detectors based on lithium fluoride (LiF). Understanding the impact of the solid substrate is crucial for customising and refining microgel coatings for specific applications. To investigate the effects of surface quality, microgel size, and particle concentration on the properties of microgel films, PNIPAM microgels were spin-coated onto LiF crystal surfaces and characterised through wettability measurements, UV-Vis-NIR spectrophotometry, and Atomic Force Microscopy. This approach enabled effective control over the optical and morphological properties of the films, paving the way for the development of hybrid and potentially biocompatible radiation detectors using PNIPAM microgel films.

Assess human blood uranium levels of some Iraqi companies

The goal of this study is to measure the uranium concentration levels in the blood of Iraqi workers employed in certain government companies. Assessing the initial level of uranium toxicity in their blood and the possibility of health problems occurring. 184 blood samples from Iraqi government companies and the control group were collected in this study. A solid-state nuclear track detector (CR-39) was used to measure the amount of uranium present. Two drops of blood (100 μl) were placed on CR-39. The CR-39 was irradiated with a thermal neutron using the fission-track technique (241Am-9Be) to determine the uranium concentration in blood samples. The statistical analysis is carried out using the Origin Lab 2024 version. The results show the average of uranium concentration at all locations has a higher level compared to the control group. The blood samples from workers at the phosphate company had the highest amount (1.021 ± 0.050 μg/l), compared to samples from other factories. This result confirms that there is a connection between the concentration of uranium and phosphate substances. The results suggest that there is a slight increase in uranium levels that is related to both age and years of employment.

Compact Ion Beam System for Fusion Demonstration

We demonstrate a compact ion beam device capable of accelerating H+ and D+ ions up to 75 keV energy, onto a solid target, with sufficient beam current to study fusion reactions. The ion beam system uses a microwave driven plasma source to generate ions that are accelerated to high energy with a direct current (DC) acceleration structure. The plasma source is driven by pulsed microwaves from a solid-state radiofrequency (RF) amplifier, which is impedance matched to the plasma source chamber at the S-band frequency in the range of 2.4–2.5 GHz. The plasma chamber is held at high positive DC potential and is isolated from the impedance matching structure (at ground potential) by a dielectric-filled gap. To facilitate the use of high-energy-particle detectors near the target, the plasma chamber is biased to a high positive voltage, while the target remains grounded. A target loaded with deuterium is used to study D-D fusion and a B4C or LaB6 target is used to study p-11B fusion. Detectors include solid-state charged particle detector and a scintillation fast neutron detector. The complete ion beam system can fit on a laboratory table and is a useful tool for teaching undergraduate and graduate students about the physics of fusion.