Tl Detector Research Articles

Absolute emission intensities of the gamma rays from the decay of 224Ra and 212Pb progenies and the half-life of the 212 Pb decay

Absolute gamma-ray emission intensities for 36 characteristic gamma rays from the decay of 224Ra, 212Pb, and their progeny were determined by measuring sources calibrated for activity by means of primary methods based on well-defined high-purity germanium (HPGe) detectors at both NIST and NPL. Results from the two laboratories agree with recent data evaluations, except for gamma rays with low emission intensities. The decay schemes have been re-balanced based on the new results. In addition, the half-life for 212Pb was measured using several HPGe detectors, ionization chambers, and a well-type NaI(Tl) detector.

Development of a radiochemical test procedure for the separation of aerosol-borne allergens

An innovative radiochemical method has been developed to determine the filtration efficiency of HEPA filters for biological nanoparticles. The setup based on EN 1822, for flat sheet media, is up to 40 times more sensitive for a single particle than methods based on particle counting, even for low particle concentrations. To achieve such a high sensitivity the radioactive tracer technique is utilised using a solution of bovine serum albumin (BSA) labelled with radioactive iodine (131I). With the aid of an aerosol generator, this solution is nebulised into nanoparticles of a defined size, which are then passed to the test filter via a compressed air flow. On the raw and clean gas side of the test filter, the 131I is measured with two NaI(Tl) detectors. By balancing the measurement data with each other, the filter efficiency can be determined. Initially, the setup has been validated with current particle counting methods, according to EN 1822, to ensure its functionality. Subsequently, the first experiments with radiolabelled nanoparticles gave promising results, as will be shown below. Further experiments also yielded information about filter clogging and its influence on the filter efficiency.

Simulation of the DD, TT and DT JET Neutron Streaming Experiments with TRIPOLI-4® Monte-Carlo code

The DD, TT and DT neutron streaming experiments (NEXP-STRE) in the fusion facility JET are here simulated with TRIPOLI-4® Monte-Carlo code. Specifically, we present the results from the simulation of the DD (2019) and the later TT and DT (2021) campaigns. The last version of TRIPOLI-4® code, developed by CEA, is provided with an innovative variance reduction technique based on the adaptive multi-level splitting (AMS) methodology for particle transport which ensures reliable results in very detailed, complex and vast geometry. Furthermore, a specific tool, developed by CEA, is used to automatically convert MCNP geometry into TRIPOLI-4® geometry format, which allows to perform fast and reliable comparisons between the results obtained by the mean of both calculation tools. The JET 360° MCNP model is used as a basis for creating the TRIPOLI-4® geometry. The neutron flux and doses in thermoluminescent detectors (TLDs) and reaction rates in activation foil (AF) detectors are computed for various positions in the experimental hall. A comparison of our results with the experimental values (2019 DD - 2021 TT campaigns) and the MCNP computed values (all campaigns) is presented. The AMS results crucial for obtaining statistically reliable quantities with TRIPOLI-4® code.

Optical and radiation shielding characteristics of Dy2O3 doped B2O3–TeO2–BaO glasses

Glass samples with varying compositions was prepared by standard approach. The composition of the samples was (50-x) B2O3–25TeO2–25BaO-xDy2O3, with x ranging from 0 to 1.25 mol%. XRD profiles confirmed that the samples were amorphous, as there were no long-range lattice arrangements observed. The successful preparation of amorphous samples was further confirmed by the absence of sharp lines & peaks. The optical properties of the obtained samples were analyzed. That a decrease in Eopt values resulted in a higher value of the refractive index (n) for the glasses. However, when the concentration of Dy2O3 exceeded certain levels (0.75, 1, and 1.25 mol%), the refractive index (n) decreased due to an increase in Eopt values. Experimental measurements using a NaI(Tl) detector were conducted to determine the radiation shielding parameters (LAC and MAC), as well as the (HVL), (TVL), & (MFP) of the glasses against gamma rays emitted by 137Cs and 60Co isotopes at energies of 0.662, 1.173, and 1.333 MeV. Excellent agreement was observed when comparing the experimental results with theoretical calculations using Phy-x/PSD software program. This suggests that the fabricated glasses have great potential for various applications in the field of optics and can effectively shield against radiation.

Experimental validation of Monte Carlo NaI(Tl) detector efficiency responses with surrogate 137Cs environmental contamination source term

Radiological site remediation is a resource intensive process requiring extensive field sampling to demonstrate regulatory compliance. Specifically, the application of Monte Carlo (MC) simulations and automated hybrid radiation transport methods has garnered interest in streamlining the remediation process by simulating detector responses for a plurality of contaminated media, contamination depths and profiles, and source-detector orientations. In this study, experimental validation of gamma-ray detector efficiency responses was conducted for simulations of radiological site-specific and idealized external contamination conditions. Measurements were performed with a cylindrical 2′′ × 2″ sodium iodide thallium-doped (NaI(Tl)) scintillator detector suspended above a 217.8 kBq, 50 cm × 50 cm 137Cs contamination source located on the surface of or buried within environmental soil. New area correction factors (ACFs) and gamma shielding factors (GSFs) were also derived to modify the simulated idealized detector efficiency responses, accounting for reductions in source area and clean soil covering layers, respectively, that may be encountered when performing in-situ gamma spectrometry in the field. The study concluded that simulated total detection efficiency from energy deposition in the active volume of the detector crystal can be adopted for radionuclide screening purposes. Furthermore, pragmatic implementation of environmental surveying using gamma-spectrometry requires site-specific information.

A comparative study of a traditional localization algorithm and a deep learning model for radioactive particle tracking application

Radioactive particle tracking is a nuclear technique that tracks a sealed radioactive particle inside a volume through a mathematical location algorithm, which is widely applied in many fields such as chemical and civil engineering in hydrodynamics flows. It is possible to reconstruct the trajectory of the radioactive particle using a traditional mathematical algorithm or artificial intelligence methods. In this paper, the traditional algorithm is based on solving a minimization problem between the simulated events and a calibration dataset, and it was written using C++ language. The artificial intelligence method is represented by a deep neural network, in which hyperparameters were defined using a Python optimization library called Optuna. This paper aims to compare the potentiality of both methods to evaluate the accuracy of the radioactive particle tracking technique. This study proposes a simplified model of a concrete mixer, six NaI(Tl) detectors, and a137Cs sealed radioactive particle. The simulated measurement geometry and the dataset (3615 patterns) were developed using the MCNPX code, which is a mathematical code based on the Monte Carlo Method. The results show a mean absolute percentage error (MAPE) of 20.81%, 10.33%, and 16.84% for x, y and z coordinates, respectively, for the traditional algorithm. For the deep neural network, MAPE is 6.87%, 2.70%, and 22.79% respectively for x, y and z coordinates. In addition, an investigation is carried out to analyze whether the size of the calibration dataset influences the performance of both methods.

Fabrication of cadmium chloride PVA polymer composite for γ-ray shielding.

Reducing the effect of exposure to radiation in places such as radiation labs, nuclear reactors, radiotherapy facilities, industries involving radiation, etc., is essential for the health of radiation workers. In such cases materials having flexibility added with high attenuation coefficient of radiation is required for manufacturing wearables. Even though materials such as lead compounds, building materials, etc., have high attenuation coefficient, they are toxic and rigid, making them unsuitable for this purpose. In this regard, blending compounds with polymers would lead to flexible materials with high shielding capability. In the present work, 25wt% cadmium chloride in polyvinyl alcohol (PVA) polymer composite has been prepared using solution casting method. The obtained polymer composite is characterised by energy dispersive X-ray spectroscopy. The mass attenuation coefficients (μ/ρ) and half value layer (HVL) of gamma radiations were measured at various energies 511, 661, 1173 and 1332keV using calibrated gamma ray spectrometer with NaI(Tl) detector and compared to WinXCom-calculated theoretical values. The measured μ/ρ and HVL are 0.089, 0.078, 0.064, 0.061cm2/g and 0.685, 0.778, 0.985, 1.003cm, respectively. It is found that the obtained experimental values are in good agreement with theoretical values within the experimental errors. Also, it is observed that the μ/ρ decreases and HVL increases with increase in energy. Even though PVA is not radiation resistant, when it is blended with 25wt% cadmium chloride it shows good shielding property. Thus, the fabricated cadmium chloride-PVA polymer composite can be used for radiation shielding instead of toxic and expensive materials.

X-ray/gamma radiation shielding properties of zinc ferrite nanoparticles synthesised via solution combustion method.

Zinc ferrite (ZnFe2O4) nanoparticles were synthesised via solution combustion method using urea as a fuel. The synthesised samples were characterised with various techniques. The cubic structure with Fd-3m space group is confirmed by Powder X-ray Diffraction and Bragg's reflection. The crystallite size estimated from Scherrer's method was found to be 40nm. The agglomerated irregular shape and sized surface morphology was confirmed by Scanning Electron Microscopy image. The direct energy band gap determined from Wood and Tauc's relation was found to be 5.25eV. Using a NaI (Tl) detector and multi-channel analyser, the described sample was examined for X-ray and gamma ray shielding characteristics in the energy range of 0.081-1.332MeV. The measured shielding values are in good agreement with the theory, however below 356keV, there is a little variation of up to 10%. The current work offers up new possibilities for using this simple, affordable, effective and low temperature approach to create nanomaterials for X-ray and gamma ray shielding.

Evaluation of outdoor radon levels and its dependence on the radium content in soil in the environs of Belagavi India

The paper presents the seasonal variation of outdoor radon levels and the measured lung dose to the population of the Belagavi region of India. The outdoor radon levels were measured in different seasons using LR-115 (type II) films fixed in a pin-hole cup detector. The outdoor radon levels in this work were found to be high in summer with values ranging from 11.8 to 27.3 Bq m−3 with a mean value of 20.0 Bq m−3. Lower radon levels were observed in monsoon season and the values range from 3.8 to 15.8 Bq m−3, with a mean value of 10.0 Bq m−3. The potential alpha energy concentration was maximum in summer with a mean value of 3.3 mWLM. The mean annual exposure was found to be 1.4 mWLM and the mean annual inhalation dose was 0.2 mSv y−1. The activity of 226Ra in soils was measured using a NaI (Tl) detector based on gamma ray spectrometer. The 226Ra activity of the study area was in the range of 16.5 to 70.4 Bq kg−1 with a mean value of 32.4 Bq kg−1. The correlation coefficient between the radium content in soil and outdoor radon levels was studied. The present study shows a significant correlation of 0.7, between outdoor radon levels and the radium content in the soil.

Radiation shielding properties of some igneous rocks in isparta province at different gamma energies: Experimental and theoretical study

In this study, our aim is to experimentally and theoretically obtain the gamma radiation shielding properties of some igneous rocks extracted in Isparta, Turkey. In the first stage, experimental measurements were performed using a gamma spectroscopy system containing a NaI(Tl) detector at three different gamma energies (511, 835 and 1275 keV) emitted from two different radioactive sources (22Na and 54Mn). As a result of the experiments, linear attenuation coefficients (LACs) of igneous rocks were obtained. The variation of LAC was investigated in relation to the density and the alkali-silica content of the rocks. The results obtained indicated an increase in the LACs with higher rock and an elevated alkali-silica ratio. Using the experimental LAC results, the half and tenth value layer thickness (HVL and TVL), mean free path (MFP), transmission rate, radiation protection efficiency (RPE) and lead equivalent thickness (dPb) values were calculated. In the second stage of this study, LACs were calculated theoretically with the help of XCOM software using the chemical contents of the selected igneous rocks. The comparison of experimentally obtained LACs with those calculated using the XCOM software, revealed a good agreement between the two methods. In addition, the results obtained with the XCOM software gave information about the variation of the attenuation coefficient in different energy regions. Moreover, effective atomic number (Zeff) and electron density (Ne) parameters were calculated using XCOM and experimental results. Based on the data collected, it can be concluded that the trachy-basalt sample taken from the igneous rocks used in this study is more effective than other rocks in terms of gamma radiation shielding.

Effect of colemanite mineral on gamma radiation attenuation properties of vinyl ester resin

In this study, it is aimed to experimentally and theoretically obtain the gamma radiation attenuation properties of vinyl ester resin (VE) containing different rates of colemanite (CO) mineral and to compare these results. In the first stage, experimental measurements were performed using a gamma spectroscopy system containing a NaI(Tl) detector at three different gamma energies (511, 835 and 1275 keV) emitted from two different radioactive sources (22Na and 54Mn). As a result of the experiments, linear attenuation coefficients (LACs) of VE samples were obtained. The variation of LACs according to the density of the samples were investigated. The obtained results showed that LACs increased the density of the VE samples increased. Using the experimental LAC results, the half (HVL) and tenth (TVL) value layer thickness, mean free path (MFP) and transmission rate values were calculated. In the second stage of the study, LACs were calculated theoretically with the help of XCOM code using the chemical contents of VE samples. As a result of the comparison of the LACs obtained experimentally and using the XCOM code, it was observed that they were in good agreement. In addition, the results obtained with the XCOM code gave information about the variation of the attenuation coefficient in different energy regions. Based on all these data, it was concluded that as the amount of colemanite in the vinyl ester resin examined in the study increased, the gamma radiation shielding performance increased.

Comparative study of optical and dosimetric properties of Mn-doped CaF2

Mn-doped CaF2 has been used as a thermoluminescence detector. On the other hand, dosimetric properties of Mn-doped CaF2 transparent ceramics have not been thoroughly investigated. In this study, transparent ceramics (TC) of Mn-doped CaF2 were fabricated, and the optical and thermally stimulated luminescence (TSL) properties were investigated in comparison with Mn-doped CaF2 single crystal (SC) and opaque ceramics (Cer). The transmittance at 500 nm of the TC, SC, and Cer specimens was 58, 91, and 0%, respectively. All the specimens showed a PL peak at 490 nm with 340, 400, and 450 nm excitations, originating from d-d transitions of Mn2+ ions. The emission and excitation spectra changed with X-ray irradiation, and this phenomenon was attributed to optically stimulated luminescence. All the specimens mainly had a TSL glow peak at 300 °C. The TC specimen exhibited a higher TSL intensity than the SC and Cer specimens.

Study of scintillation properties and performance of CsI(Tl) detectors over time

This work presents a systematic study of the properties (Light Output Non-Uniformity (LONU) and energy resolution) of two CsI(Tl) scintillation units over a span of almost three years, under adverse conditions of humidity and temperature. These two crystals are part of the CALIFA detector, a highly segmented calorimeter and spectrometer for γ rays and light-charged particles, that is placed surrounding the reaction target at Cave C, the experimental cave of the R3B (Reactions with Radioactive Relativistic Beams) collaboration at the GSI-FAIR facilities in Darmstadt, Germany. The findings obtained after the experiment indicate that there was no significant impact on the performance in terms of resolution and LONU. This suggests that the employed wrapping for light collection effectively serves as an excellent barrier against humidity. As a result, the crystal is preserved in a far better condition than initially anticipated.

A Fiber-Optical Dosimetry Sensor for Gamma-Ray Irradiation Measurement in Biological Applications.

In this paper, we propose a novel fiber-optical dosimetry sensor for radiation measurement in biological applications. A two-dimensional (2D) fiber-optical dosimeter (FOD) for radiation measurement is considered. The sensors are arranged as a 2D array in a tailored holder. This FOD targets accurate industrial and medical applications which seek more tolerant radiation dosimeters. In this paper, the FOD sensors are subjected to gamma-ray radiation facilities from the 137Cs gamma-ray irradiator type for low doses and 60Co gamma-ray irradiator for high doses. For better evaluation of radiation effects on the FOD sample, the measurements are performed using eight sensors (hollow cylinder shape) with two samples in each dose. The sensors were measured before and after each irradiation. To the author's knowledge, the measurements of FOD transplanted inside animals are presented for the first time in this paper. A 2D simulation program has been implemented for numerical simulation based on the attenuation factors from the absorbed dose inside the in vivo models. A comparison between the FOD and the standard thermo-luminescence detector is presented based on the test of in vivo animal models. The results indicate that the proposed FOD sensor is more stable and has higher sensitivity.

Effects of Natural Radioactivity of Some Chemical and Organic Fertilizers on Gonads in Iraqi Kufa Markets

This study assessed the hazard indicators of common chemical and organic fertilizers widely available in the markets of Najaf Governorate, Iraq. The concentrations of natural radionuclides were measured in thirteen types of fertilizers by Gamma spectrum using NaI(Tl) (3*3) detector. The average radioactivity of the nuclides 226Ra, 232Th, and 40K was (48.91, 37.04, and 702.4675) Bq.kg-1, respectively, for (Di-Aluminum Phosphate) the chemical fertilizers of the type (DAP) and the (nitrogen, phosphorus, and potassium) chemical fertilizers of the type (NPK) the average radioactivity of the nuclides 226Ra, 232Th, and 40K were (35.78, 42.356 and 1519.653) Bq.kg-1, respectively, while the average radioactivity of the organic fertilizers (Orga.) were 55.153, 23.148 and 1451.258 for the three studied nuclei. As for the average values for radium equivalent were 155.967, 213.363, and 200.0023 (Bq.kg-1) for (DAP), (NPK) and organic fertilizers, respectively. The values of the external severity index (Hex), gamma radiation hazard index (Iγ), and representative alpha index (Iα) were within the permissible limits determined by the UNCEAR 2000. The highest value of total annual effective dose equivalent(TAED) was 1.468 mSv.y-1, the lowest value was 0.302 mSv.y-1, and the mean values were 0.722 mSv.y-1. In contrast, the highest value for annual gonadal dose equivalent(AGED) was 1392.527 μSv.y-1, the lowest value was 275.361 μSv.y-1, and the average values for all models were 672.135 μSv.y-1. The Excess Lifetime Cancer Risk (ELCR), the highest value was 4.039 × 10-3, the lowest value was 0.833× 10-3, and the average value was 1.988× 10-3 for all fertilizers. The Pearson correlation between radioactive variables and cluster analysis was recognized for the three types of fertilizer samples despite it not being widely accepted. The study can be considered preliminary data for subsequent studies.

Characterization and performance of SiPM-CsI(Tl) detector for low-energy [formula omitted]- and X-ray spectroscopy

In this study, we coupled the low background CsI(Tl) crystal to a SensL J-series 60035 SiPM and detected low-energy γ and X-rays from Cobalt (57Co) and Iron (55Fe) radioactive sources. A distinct and well-resolved 5.9 keV X-ray peak was observed from the 55Fe source. The 6.4 and 14.4 KeV X-ray peaks from the 57Co source were measured and found to be very well separated from the background as well. Based on the SiPM single photoelectron peak mean value, the light output of CsI(Tl)+SiPM detector and absolute light yield of CsI(Tl) was calculated down to 5.9 keV. After correcting the reflectivity, and crosstalk factor the Absolute light yield was estimated to be 55 ± 3 ph/keV. The detector light output in terms of photoelectron per equivalent energy was calculated to be 13 ∼16PE/keVee. Furthermore, measurements of energy resolution and non-proportionality were done all the way down to the X-ray region. According to our findings, the SiPM coupled to CsI(Tl) could be an excellent detector for lower energy experiments such as dark matter searches and can be used in the study of neutrino physics as well as other high energy physics experiments.

Clay-based bricks’ rich illite mineral for gamma-ray shielding applications: An experimental evaluation of the effect of pressure rates on gamma-ray attenuation parameters

Abstract The objective of this study is to increase the natural clay mineral-based bricks’ ability to shield γ-rays without the use of external doping materials. Six brick samples were consequently developed at various pressure rates (PRs). The chemical composition and structure of the manufactured bricks are unaffected by the PR applied. The main constituents in the clay used to make bricks are illite and quartz minerals, according to an X-ray diffraction pattern. Additionally, scanning electron microscopy and energy dispersion X-rays have demonstrated the morphology and chemical composition of the used clay. Besides, the Mh-300A density meter shows an increase in the fabricated bricks’ density by increasing the PR, where the brick’s density increased by 32.92% by increasing the PR from 7.61 to 114.22 MPa, respectively. Also, the effects of the PR on the radiation shielding properties of the fabricated bricks were investigated using a NaI (Tl) detector. The data reveal that increasing the PR between 7.61 and 114.22 MPa improved the linear attenuation coefficient by 44.5, 23.8, 24.2, and 24.8%, respectively, for gamma-ray energies of 0.662, 1.173, 1.252, and 1.332 MeV. The capacity of fabricated bricks to shield against radiation increases as the linear attenuation coefficient increases. The lead’s equivalent thickness and half-value thickness of the fabricated clay-based bricks, on the other hand, decreased. As a result, the compacted natural clay brick, which is a lead-free material, provides a suitable alternative for gamma-ray shielding in radioactive locations.

Radioactivity in a bucket

In radiation physics classes, point sources are typically used, for which it is relatively easy to describe the signal obtained by a radiation detector, such as the NaI(Tl) scintillation detector. The use of large extended radiation sources is generally avoided due to the mathematical complexity that their description may involve. However, the use of Monte Carlo simulation methods allows this limitation to be overcome. Potassium chloride, containing the 40K isotope, is an ideal candidate for carrying out this type of experiment. The source activity is obtained through the detection of the 1460.8 keV gamma-photon emitted in the 40K decay. In the first experiment, a cylindrical container is used, placing the NaI(Tl) detector in its center and filling the remaining space with potassium chloride. In a second, more complex case, a large radioactive source consisting of a container filled with a mixture of sand and potassium chloride, with the NaI(Tl) detector placed in the center of the mixture, is used. In this case, the mass of potassium chloride is approximately 1/5 of the sand mass. In both experiments, the detection efficiency is obtained by Monte Carlo simulation. A careful analysis of the experimental data allows to obtain a good agreement between the measured and calculated value of the activity.

Determination of natural radioactivity using gamma spectrometry in used soils as construction materials in Qom province, Iran

The concentrations determination of natural radionuclides as radiation sources has an important role in reducing radiation risk and evaluating of non-nuclear activities impact. In this research, the concentrations of natural radionuclides 40K, 226Ra, and 232Th in the soil samples collected from 13 different locations in the Qom province (Delijan Cement Mine area) were measured by means of gamma-ray spectrometry using a shielded NaI (Tl) detector. For this purpose, the Nuclide master plus simulation program was used to evaluate the efficiency, and then the acquired data was validated. The activity concentrations of 40K, 226Ra, and 232Th varied within the ranges of 23.19 ± 1.95 to 287.19 ± 2.38, 3.04 ± 0.47 to 13.43 ± 0.56, 2.26 ± 0.37 to 4.63 ± 0.38 Bq.kg−1 with the mean values of 75.78, 8.69, and 3.30 Bq.kg−1, respectively. Radium equivalent activity, internal and external hazard indices were determined to assess radiological hazards. The mean Raeq was measured 19.26 Bq.kg−1 and Hex and Hin were calculated 0.052 and 0.075 which these quantities were lower than the world average. The results revealed that radiological risk due to natural radionuclides in this area was negligible and extracted soil samples as construction materials (cement) are safe.

Radiation shielding properties of barite coated terry-cotton fabric

With the rapid development of technology, the radiation started to be used in many different fields and thus radiation protection becomes important. The use of radiation in basic science, industry, military purposes and medical applications has reached enormous dimensions. The protection of radiation, which has such a wide range of uses, has become inevitable. Dresses used by radiation workers are important against possible radiation damage. In this study, the linear attenuation coefficients have been measured to investigate the radiation shielding properties of terry-cotton fabric coated by barite in the rate of 0%, 40%, 50% and 60%. The measurements were performed using a NaI (Tl) detector at 511, 835 and 1275 keV gamma ray energies. It was found that the barite is an important materials and when it is used to coat fabric lead to improve radiation shielding properties.