137Cs Source Research Articles

The impact of strontium composition on thallium-doped cesium iodide scintillators

Investigating new scintillators with more alternative methods has been an attractive topic for a long time. This work aims to study the impact of strontium composition on thallium-doped cesium iodide scintillators. There are three different composition ratios of cesium iodide and strontium iodide precursors of 99:1, 95:5, and 90:10 with the same thallium doping of 0.28 mol%. The EDS measurements analyzed the soluble Sr-compositions in these grown crystals as 0%(undetectable), 0.43%, and 2.31%, respectively. With slightly increased strontium composition, the crystallite size was slightly smaller from 59.17, 45.51, to 33.23 nm, respectively. Moreover, the crystals have a somewhat more compressive strain and a slightly higher single crystallinity when the composition of strontium iodide increases. By analyzing the crystals' optical properties, the luminescent properties were trivially enhanced with a bit higher scintillation light yielding up to 29,859 photon/MeV of the crystal with a Sr-composition of 2.31%. Photoluminescence measurements exhibit the enhanced 520 nm scintillation and the lower 410 nm emission at higher Sr contents. These crystals’ emission decay times were obtained as τ1 = 500 ns (fast component) and τ2 = 700 ns (slow component) and slightly slower times with a higher Sr content. Lastly, radiation detection efficiency has been investigated at various energy levels of gamma rays from Am-241, Co-57, Ba-133, and Cs-137 sources. We found that the crystal with a higher Sr composition of 2.31% has better energy resolutions down to the best one of 7.9% at 662-keV measurement. In summary, higher strontium codoping with thallium in cesium iodide scintillators can enhance the crystal structure and optical properties. This would be one candidate of the promising scintillators for developing alternative high-performance radiation detectors for high-speed imaging applications.

Experimental investigation of gamma radiation shielding ability of some building materials in Bitlis (Turkey)

Considering that people spend most of their time in buildings (home, office, school, shopping mall, etc.), it is seen that the radiation retention properties of building materials are important. Nuclear power plants are a complex of structures that are of great importance in today's energy-age world, but also bring some dangers. The most important of these dangers is the possibility of radiation leakage from these structures in the event of an explosion. In addition, shielding for radiation protection is important in medical applications and industry where radiation is widely used. Therefore, the strength and durability properties of concretes to be used in the construction of nuclear power plants need to be meticulously designed. All this shows how important and worthy of research the subject of the study is. For this purpose, new materials that are easy to access, abundant and cheap, and have high absorption capability are needed, rather than shield made only of lead materials. Perlite, pumice and Ahlat stones are abundant in Bitlis (Turkey) province and are extracted from the quarries. The bims block samples (B-1, B-2 and B-3) produced in factories in Bitlis. This study was carried out to investigate whether these materials, which are used as building materials, have radiation absorbing properties in terms of their use in different areas. Linear attenuation coefficients were calculated experimentally for gamma energies at 88.04 ± 0.01 keV, 356.50 keV, 661.60 keV, 834.80 ± 0.04 keV and 1173.20–1332.50 keV (for 109Cd, 133Ba, 137Cs, 54Mn and 60Co radioactive point sources) using gamma spectrometry with a NaI scintillation detector. In addition, photon absorption percentages, half value layer (HVL), tenth value layer (TVL) and mean free path (MFP) values of the samples were calculated. The obtained data were evaluated by comparing with similar studies in this field and the results obtained for lead shield. As a result of the study, it is seen that instead of using perlite and pumice alone, it is better radiation trap when they are mixed with each other and formed into bims blocks.

Influential factors of long-term and seasonal 137Cs change in agricultural and forested rivers: Temperature, water quality and an intense Typhoon Event

In this study, the effect of temperature, water quality, and the impact of an intense typhoon event on change in 137Cs concentration in the water of agricultural and forested rivers near the Fukushima Daiichi nuclear power plant (Japan) was evaluated using monthly stationary observations obtained under baseflow conditions 2.8–10.6 years after the nuclear accident in 2011. The dissolved 137Cs concentration fluctuated seasonally with water temperature in all rivers, and the increase in dissolved 137Cs concentration for unit increase in temperature was higher in forested rivers than in agricultural rivers. The relationship between water temperature and the apparent distribution coefficient of 137Cs well followed the van ’t Hoff equation in the two agricultural rivers, where the enthalpy of reaction was estimated as −15.6 and −19.6 kJ mol−1. The van ’t Hoff equation was not well followed for a forested river, where the suspended solids mainly comprised organic matter, suggesting that the dominant process determining dissolved 137Cs concentrations in forested rivers is not only water temperature effect on ion exchange, but rather the input of 137Cs and K+ (competing with 137Cs for exchange sites on mineral particles) into the water phase via litter leaching. Suspended solids concentrations in agricultural rivers correlated negatively with 137Cs concentrations in suspended solids, suggesting an increased proportion of coarse particles or the input of soils with low 137Cs concentration from decontaminated agricultural land. At some sites, 137Cs concentrations in dissolved form and in suspended solids were reduced sharply in association with the passage of Typhoon Hagibis in October 2019, suggesting that Typhoon Hagibis caused large-scale surface erosion that removed the source of 137Cs.

Development of a real-time gamma camera for high radiation fields

In high radiation fields, gamma cameras suffer from pulse pile-up, resulting in poor energy resolution, count losses, and image distortion. To overcome this problem, various methods have been introduced to reduce the size of the aperture or pixel, reject the pile-up events, and correct the pile-up events, but these technologies have limitations in terms of mechanical design and real-time processing. The purpose of this study is to develop a real-time gamma camera to evaluate the radioactive contamination in high radiation fields. The gamma camera is composed of a pinhole collimator, NaI(Tl) scintillator, position sensitive photomultiplier (PSPMT), signal processing board, and data acquisition (DAQ). The pulse pile-up is corrected in real-time with a field programmable gate array (FPGA) using the start time correction (STC) method. The STC method corrects the amplitude of the pile-up event by correcting the time at the start point of the pile-up event. The performance of the gamma camera was evaluated using a high dose rate 137Cs source. For pulse pile-up ratios (PPRs) of 0.45 and 0.30, the energy resolution improved by 61.5 and 20.3%, respectively. In addition, the image artifacts in the 137Cs radioisotope image due to pile-up were reduced.

Anti-Compton shield for Compex germanium detector modules

A bismuth-germanate (BGO) anti-Compton shield (ACS) for Compex germanium detector modules was designed, built, and characterised. BGO performance was evaluated for light output and energy resolution. The response of the ACS shield and its impact on germanium detector spectra was measured for standard 60Co, 133Ba, and 137Cs sources. The results were compared to comprehensive Geant4 simulations. The ∼70% improvement of the peak-to-total ratio for the 137Cs 662-keV γ-ray peak is in good agreement with expectations from the simulations. A 133Ba source exemplifies decay schemes of odd-A superheavy nuclei. Congruence between measured and simulated spectra indicates that the Compex plus ACS multi-detector module is well understood.

The Effect of Multi-Wall Carbon Nanotubes Addition on the Shielding Properties Against Gamma Radiation

In this work, the effect of Multi-Wall Carbon Nanotubes (MWCNTs) addition on the materials shielding properties against Gamma radiation with an energy of 662 keV from a 137Cs source is investigated. The linear attenuation coefficient of MWCNTs-based materials (gelatin-water mixture) with MWCNTs concentrations of 0%, 5%, and 10% is measured. To isolate the contribution of the MWCNTs unique structure to the shielding capabilities, samples with the same concentrations of activated carbon were fabricated and their linear attenuation coefficients were obtained. Also, the linear and the mass attenuation coefficients are obtained theoretically for the same concentrations using the XCOM program and compared with measured values. It is found that the addition of MWCNTs by 5% or 10% has increased the linear attenuation coefficient by around 5% when compared to the same concentrations of activated carbon. This increase in the shielding apabilities against gamma radiation can be related to the interaction of gamma radiation with the extraordinary geometry and structure of MWCNTs.

Gamma spectrometer calibration of liquid standard sources of Mix 133Ba, 137Cs and 60Co toward the measurement of 99Mo breakthrough of 99Mo/99mTc generator

The expression radionuclide in nuclear medicine is preferred than radioisotope which widely used in physics. Radionuclides have been used regularly in nuclear medicine. Their radiation provide information about the staging of a person’s specific organs and to specify what is triggering the symptoms, injury or disease to treat diseased organs or cancerous tumours in a patient called theranostic. Technetium-99m radionuclide is the most frequently used radionuclide in nuclear medicine. The quality control of technetium-99m (99m Tc) product from 99Mo/99mTc generator is crucial. One that have been highlighted in this paper is the radionuclide molybdenum-99 (99Mo) breaktrough which can be effectively measured using caliberated gamma spectrometer. The stability test of the gamma spectrometer detector is done using control chart and chi square method from 137Cs radionuclide measurement. The calibration process of liquid standard sources of mix 133Ba, 137Cs and 60Co including energy and efficiency calibration, are performed with the same geometry as Mo99 breakthrough measurement in a lead shield canister with 2.5; 4.5 and 8.5 cm distance from the HPGe detector. The result from the calibration of liquid standard sources of mix 133Ba, 137Cs and 60Co showed the required polynomial equations needed to calculate the 99Mo breakthrough of 99mTc eluted product from the 99Mo/99mTc generator.

Compton Camera Arrangement With a Monolithic LaBr3(Ce) Scintillator and Pixelated GAGG Detector for Medical Imaging

The results presented in this manuscript are divided in two main parts. The aim of the presented work is to conduct feasibility tests on a Compton camera setup to be later scaled up and used for PET and triple coincidence γ-PET purposes. The first part is focused on laboratory characterization of a monolithic LaBr3(Ce) scintillator coupled to a 64-channel multi-anode photomultiplier (H8500C PMT from Hamamatsu) in combination with a well-established algorithm allowing to determine the interaction’s position resolution. The second part of the article is dedicated to the evaluation of a Compton camera detector arrangement in which the monolithic scintillator acts as an absorber, while a pixelated GAGG scintillator array, read out by a SiPM multi-pixel photon counter (MPPC), is used as a scatterer component. The accuracy achievable with this system for detecting γ rays from laboratory point sources is investigated. The Compton camera system has been tested with radioactive 137Cs and 60Co point sources. The signal readout and data acquisition system is based on individual spectroscopy electronics modules (NIM and VME), for the absorber and a customized electronics based on Anger logic for the GAGG scatter array. The raw data were analyzed to serve as input for the image reconstruction, performed using the MEGAlib toolkit software. With a spatial resolution of 1 mm for the scatterer and less than 3 mm for the absorber component, respectively, shifts of 2 mm of both radioactive sources (137Cs and 60Co) could be resolved with the whole Compton camera system.

Disproportionately High Contributions of 60 Year Old Weapons-137Cs Explain the Persistence of Radioactive Contamination in Bavarian Wild Boars.

Radionuclides released from nuclear accidents or explosions pose long-term threats to ecosystem health. A prominent example is wild boar contamination in central Europe, which is notorious for its persistently high 137Cs levels. However, without reliable source identification, the origin of this decades old problem has been uncertain. Here, we target radiocesium contamination in wild boars from Bavaria. Our samples (2019-2021) range from 370 to 15,000 Bq·kg-1 137Cs, thus exceeding the regulatory limits (600 Bq·kg-1) by a factor of up to 25. Using an emerging nuclear forensic fingerprint, 135Cs/137Cs, we distinguished various radiocesium source legacies in their source composition. All samples exhibit signatures of mixing of Chornobyl and nuclear weapons fallout, with 135Cs/137Cs ratios ranging from 0.67 to 1.97. Although Chornobyl has been widely believed to be the prime source of 137Cs in wild boars, we find that "old" 137Cs from weapons fallout significantly contributes to the total level (10-68%) in those specimens that exceeded the regulatory limit. In some cases, weapons-137Cs alone can lead to exceedances of the regulatory limit, especially in samples with a relatively low total 137Cs level. Our findings demonstrate that the superposition of older and newer legacies of 137Cs can vastly surpass the impact of any singular yet dominant source and thus highlight the critical role of historical releases of 137Cs in current environmental pollution challenges.

Gamma radiation shielding properties for polymer composites reinforced with bismuth tungstate in different proportions

In this study, inorganic compound (Bi2(WO4)3) was added into the composite to improve the radiation shielding properties of polymer composite. A polymer matrix was prepared by combining unsaturated polyester resin with methyl ethyl ketone peroxide and cobalt octoate (6%), and Bi2(WO4)3 was added to this polymer matrix at different ratios as filling material. In order to investigate the gamma radiation attenuation properties of the obtained polymer composites, mass attenuation coefficients, radiation shielding efficiencies, radiation transmission factors, linear attenuation coefficients, half values layer, tenth values layer, mean free path values, effective atomic numbers and effective electron densities parameters were obtained. Experimental studies were carried out with the help of HPGe detector at 22 different energies emitted from 22Na, 54Mn, 57Co, 60Co, 133Ba, 137Cs, 152Eu and 241Am radioactive sources in the photon energy range of 59.5–1408.0 keV. Each obtained experimental result was compared with the theoretical results. It was observed that the sample encoded with BiWO20 is the best radiation shielding material among all studied composites (except 59.5 keV).

Effect of gamma ray on self-induced diffraction patterns of organic compound Poly (methyl-methacrylate films

Poly (methyl-methacrylate) (PMMA) doped organic compound (2-(2,3-dimethylphenyl-amino)-N-Phenyl benzamide) (2-NPb (films are produced on glass substrates with 5 μm thickness. The influence that gamma (γ) radiation has on the structure of the surface morphology of polymer films, the structure dependence of the optoelectronic properties and the optical properties of a prepared 2-NPb:PMMA film was studied under different doses (21, 42 and 64 KGy) of γ- rays emitted by a 137Cs source with an exposure rate of 0.56 Gy/min. The surface morphology of the 2-NPb:PMMA film for un-irradiated and irradiated sample was studied using a microscope with a digital camera along with texture, waviness and roughenss analysis of the entire surface of the films. The optical properties, together with an in-depth analysis of the dispersion energies and parameters, optoelectrical characteristics, and certain nonlinear optical parameters were comprehensively examined and addressed. In addition, the study of optical properties also included some nonlinear optical parameters. Results show that by doping organic compound (2-NPb) in PMMA, the absorption spectra of samples are decreased and superficial morphology of the film has been affected by γ-rays. As the polymer film was irradiated with a continuous-solid state laser (Solid-State-Laser −532–100 T) beam of 532 nm, self-diffraction ring patterns were seen, and it was shown that the diffraction ring patterns rely heavily on ring numbers and radiation dosage. The nonlinear refractive index,n2, for polymer film for un-irradiated and irradiated are estimated to be 0.23×10-6, 0.92×10-6, 1.64×10-6, 3.14×10-6cm2/W, respectively due to diffraction ring patterns. The diffraction ring patterns that were acquired via experimentation are then numerically estimated by making use of the Fresnel-Kirchhoff diffraction integral. The results of these calculations have satisfactory qualitative and quantitative accords.

Calibration and simulation of a silicon dosemeter for ambient dose equivalent in low-earth orbit space.

A particle dosemeter (PD) is a payload of NEXTSat-2 in the low-earth orbit (LEO). The absorbed dose in LEO needs to be converted into the ambient dose equivalent (H*(10)). Due to a mixed field in LEO, the calibration factors (klow and khigh) should be determined for the low-and high-linear energy transfers (LET) (below and above 1.5keV/μm), respectively. The PD was irradiated with a 137Cs source at the Korea Radiation Solution facility to obtain H*(10) and absorbed doses. However due to the lack of sources for the high-LET calibration, H*(10) and an absorbed dose were calculated by simulating PD for the high-energy neutron field at CERN-EU high-energy Reference Field. The measured klow of PD had a difference of 5.1% and 9.5% from the calculated value of PD and the measured value of Liulin detectors, respectively. However, a difference in khigh between PD and Liulin was explained by the contribution of non-neutron components to Liulin in the measurements.

Newly-formulated zinc-bismuth-barium-sodium-silicate glass system with lead oxide addition: Probing radiation shielding characteristics via triple methodology

In recent times, glass materials appear to be strong candidates for radiation protection applications. In this study, a zinc-bismuth-barium-sodium-silicate (ZBBSS) glass system with a formulation of 10ZnO – 20Bi2O3– 5BaO – 15Na2O – (50-x) SiO2– xPbO, x: 0, 5, 15 and 25 wt% was synthesized. The traditional melting technique (1325–1375 °C) enabled the synthesis of four different glass samples coded ZBBSS1 to ZBBSS4. Following synthesis, Archimedes' principle, XRD, FTIR, UV-Vis, and DSC techniques showed physical, structural, optical, and thermal property alterations as a function of PbO inclusion, while the triple methodology (experimental, theoretical, and simulation) revealed radiation attenuation aspects in a broader sense. According to the findings, ZBBSS1 had density of 3.1107 g/cm3 while the other samples had density values of 3.2285, 3.6053, and 4.0158 g/cm3 in respective order. The clear existence of non-crystalline structure for the ZBBSS glass series was reported. Similar vibrational modes were found for ZBBSS glass systems, and -OH, Si-OH, Si-O-Si, and Pb-O-Pb bonding types were assigned to peak formations. For determination of thermal properties, it was observed that Tg became lower, from 520.6 to 392.4 °C, in parallel to the increment in the PbO doping rate. Additionally, an increase in the PbO doping rate hindered the transmission phenomenon based on UV-Vis spectra. Gamma absorption coefficients were measured at six energies with four sources using the gamma spectroscopic system. The measured values were compared with the FLUKA code and Phy-X software. Experimental LAC values of 0.2463, 0.2729, 0.3064, and 0.3618 cm−1 were measured using a Cs-137 source for the ZBBSS glass series, respectively. The variation in the values obtained with the triple methodology overlapped with each other for all energies. Among the prepared glasses, the best LAC and MAC, thinnest HVL, lowest MFP and TF were determined for ZBBSS4 glass sample with maximum PbO content. From the results obtained, it is concluded that the addition of PbO is a useful way to improve the gamma attenuation capacity, and among the glasses examined, ZBBSS4 had superior protection against gamma rays.

Bi-PMMA composite materials and their shielding capability for low energy gamma rays

The composite materials filled with different metal particles could provide the potential to meet the proper advantages for gamma radiation protection in both medicine and industry. In this paper, a new, fast, simple and low costing synthesis of bismuth powders using aluminum foil is presented as a gamma-shielding alternative to lead and cement base materials. The synthesized powders were characterized by XRD and FE-SEM. Flexible Bi-PMMA composites having 40, 50 and 60 wt% of bismuth were subsequently prepared and their gamma-shielding properties were investigated. The attenuation constants of the composites such as linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), and mean free path (MFP) were then obtained using the relevant measured values at available energies of Am-241, Cs-137 and Co-60 gamma sources. Gamma-shielding properties of the composites (at each gamma energy) were improved with the weight percentage increase of the bismuth powder in the polymer matrix but on the other hand the shielding capability reduced with the increase of the gamma energy. The HVL value for the sample containing 60 wt % of bismuth powder at a gamma energy level of 59.5 keV was found to be 0.072 cm. This HVL value was very close to that of lead, 0.068 cm, at the same energy. Moreover, the developed composites had the following features: easy and rapid fabrication process, nontoxic nature, lightweight, flexible, environment-friendly, and cost-effective.

Effects of nano titanium and nano silica on high‐strength concrete properties incorporating heavyweight aggregate

AbstractThis investigation aims to study the effect of replacing 100% of fine and coarse aggregates with heavyweight aggregates and adding nano titanium (NT) and nano silica (NS) on shielding against radiation and on the mechanical and transport properties of heavyweight high‐strength concrete (HWHSC). In this study, 20 mixes were prepared that included the use of hematite and steel slag (SS) aggregate with NS or NT used as additions to mixes by the ratio 1% and 3% from cement weight. To study the effect of the total replacement of aggregates and the addition of nanomaterials (NMs) on the properties of HWHSC, to study engineering properties the slump, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were applied. Density, chloride permeability, sorptivity coefficient, water permeability, and microstructure tests were also performed. To study the efficiency of shielding against radiation, linear attenuation coefficient, mass attenuation coefficient, mean‐free path, half‐value layer, and tenth‐value layer of different gamma‐ray sources of radiation 137Cs 662 (keV) and 60Co 1332 (keV) were applied. The results showed that the 100% SS and hematite replacement as coarse and fine aggregates with 3% (NS or NT) achieved the best mechanical and transport properties compared to other mixtures. While the highest density of the string containing hematite and SS was achieved with 3% of NT, with a density of 3384 kg/m3. The highest compressive strength of more than 116 MPa was achieved for the included mixture of 3% NS. The highest attenuation of gamma‐ray radiation was achieved with the application of hematite and SS aggregates with 3% of NT.

Effect of Barium Sulfate Nanoparticles with Organic Alcohol on the Ionizing Radiation Shielding

In this study, the gamma ray shielding properties of shields prepared from polyvinyl alcohol as a base material reinforced with barium sulfate nanoparticles at different reinforcement ratios (5,15,25,35,45 %) and thickness 1 cm were studied. To determine the acceptability of these shields for use in gamma ray protection, some parameters including linear attenuation coefficient (μ), mean free path (λ), and half value layer (HVL) were determined using133Ba, 22Na, 137Cs, and 60Co radioactive sources that produced gamma rays with energies of (356, 662, 1173, 1275 and 1332 KeV). The (NaI (Tl)) gamma system was employed for this purpose. The fabricated shields' effective atomic number was also determined. The findings demonstrated that as the reinforcement ratios of the nano-barium sulfate were raised, the linear attenuation coefficient and the effective atomic number of the shields inceased . The mass attenuation coefficient , mean free path and the half value layer decreased as the nano-barium sulfate reinforcement ratios increased.

Growth and Scintillation Properties of Na+-Doped CsCu2I3 Single Crystals

CsCu2I3 crystal is a promising Cu-based halide material for scintillation detection. In this paper, Na+ ion-doped CsCu2I3 crystals with a size of ϕ12 mm × 50 mm were grown successfully using the vertical Bridgman method, and the properties were systematically investigated. CsCu2I3:Na crystals exhibit yellow light emission peaking at 575 nm and a large Stokes shift of 1.55 eV. Based on the results of the XRD and XPS, the Na+ was introduced successfully. The optical absorption spectra show that the band gap of CsCu2I3 crystals was narrowed when the Na+ was doped. The photoluminescence quantum efficiency (PLQY) is improved from 16.4% to 19.6%. Finally, the X-ray-induced afterglow, and scintillation (energy resolution, light yield and decay time) under a 137Cs source were measured and discussed. These results illustrate that CsCu2I3:Na crystals have potential applications in the radiation detection field.

An extendable optical fibre probe survey meter for naturally occurring radioactive material (NORM) and other weak emitters

We have developed a radioluminescence-based survey meter for use in industries in which there is involvement in naturally occurring radioactive material (NORM), also in support of those needing to detect other weak emitters of radiation. The functionality of the system confronts particular shortcomings of the handheld survey meters that are currently being made use of. The device couples a LYSO:Ce scintillator with a photodetector via a polymer optical fibre waveguide, allowing for "intrinsically safe" inspection within pipework, separators, valves and other such component pieces. The small-diameter optical fibre probe is electrically passive, immune to electromagnetic interference, and chemically inert. The readout circuit is entirely incorporated within a handheld casing housing a silicon photomultiplier (SiPM) detection circuit and a microprocessor circuit connected to an LCD display. A 15 m long flexible PMMA optical fibre waveguide is butt coupled to an ABS plastic probe that retains the LYSO:Ce scintillator. Initial tests have included the use of lab-based mixed gamma-ray sources, measurements being made in concert with a reference conventional GM survey-meter. Characterization, via NORM sources at a decontamination facility, has shown useful sensitivity, covering the dose-rate range 0.10- to 28 µSv h−1 (R-squared 0.966), extending to 80 µSv/h as demonstrated in use of a Cs-137 source. The system is shown to provide an effective tool for detection of radioactivity within hard to access locations, in particular for sources emitting at low radiation levels, down to values that approach background.

An entrance window surrounded phoswich design for efficient large-angle Compton-suppressed and low-background GAGG: Ce detector

An entrance window surrounded phoswich design of GAGG:Ce/CsI:Tl has been implemented for a low-background and Compton-suppressed detector. Not as the common phoswich detector does, the GAGG:Ce scintillator with the well-type CsI:Tl scintillator entrance window surrounded makes the efficient large-angle Compton suppression. This design also makes results measured by the phoswich detector have no degradation compared with the single GAGG:Ce detector. The Compton continuum and other backgrounds are reduced by identifying the gamma-ray energy depositions in different scintillators using the real-time rise time discrimination (RTD) method. The background rate is suppressed approximately 74%. The peak-to-total (P/T) ratio at 137Cs and 60Co point sources are 0.769 and 0.561, respectively. The Compton suppression is highly efficient at all the energy range of Compton continuums. The reduction of the Compton continuum and other backgrounds and the improvement of the P/T ratio will greatly expand the application range of the GAGG:Ce detector in low-intensity measurements.

Transfer of 137Cs and 90Sr from soil-to-potato: Interpretation of the association from global fallout in Aomori to accidental release in Fukushima and Chornobyl

Ceasium-137 and 90Sr are major artificial radionuclides that have been released into the environment. Soil-to-plant transfer of radionuclides is an important route to food contamination. The radionuclide activity concentrations in crops must be quantitatively predicted for estimating the internal radiation doses from food ingestion. In this study, soil and potato samples were collected from three study sites contaminated with different sources of 137Cs and 90Sr: Aomori Prefecture (global fallout) and two accidental release areas (Fukushima Prefecture and the Chornobyl exclusion zone). The 137Cs activity concentrations in the soil and potato samples widely ranged from 1.0 to 250,000 and from 0.048 to 200,000 Bq kg−1 dry weight, respectively. The soil-to-potato transfer factor of 137Cs also ranged widely (0.0015–1.1) and decreased with increasing concentration of exchangeable K. Meanwhile, the activity concentrations of 90Sr in the soil and potato samples were 0.50–64,000 and 0.027–18,000 Bq kg−1 dry weight respectively, and the soil-to-potato transfer factor of 90Sr was 0.023–0.74, decreasing with increasing concentration of exchangeable Ca. The specific activity ratios of 137Cs/Cs and 90Sr/Sr in the exchangeable fraction were similar to those in potatoes, with a factor of 3 in the ±95 % confidence intervals over six orders of magnitude and a factor of 2 in the ±95 % confidence intervals over five orders of magnitude, respectively. According to the data, the accuracy of predicting the activity concentrations of 137Cs and 90Sr in potatoes can be improved by applying the specific activity ratios of 137Cs/Cs and 90Sr/Sr in the exchangeable fraction. This approach accounts for variable factors such as the effects of K and Ca fertilization and soil characteristics. It also emphasizes the benefit of determining the stable Cs and Sr concentrations in potatoes and other crops prior to possible future contamination.