Gas Proportional Detectors Research Articles

Improvement of nuclear photon and neutron shielding performance of Tm2O3 and Dy2O3 doped ceramics: An experimental study

In this study, 60KAlSi3O8+10Al2Si2O5(OH)4+(30-x)SiO2+xA2O3 (x = 0, 10, 20, 30 wt% and A = Tm, Dy) ceramics were produced by conventional method to determine their usability as shielding material against ionized gamma radiation. To investigate the ionized photon shielding properties of the fabricated materials, the photon intensities (I and I0) were experimentally measured at 81, 160, 223, 302, 356, and 383 keV energies emitted from 133Barium radioisotope, and then the mass attenuation coefficient (μρ), The linear attenuation coefficients (μ, cm−1), half-value thickness (Δ0.5), mean free path (λ), effective atomic numbers (Zeff) and electron densities (Nel) were derived experimentally. The obtained results were benchmarked with the calculated values from the EpiXS program. Also equivalent absorbed dose (EAD) values for fast neutrons were measured using BF3 gas proportional neutron detector from the Canberra NP-100B series and a241Am/Be neutron source with a 10 mCi activity. In addition, fast neutron shielding parameters (ΣR) of ceramics were also computed theoretically. The density of the fabricated ceramics varied from 2.607 g/cm3 to 4.392 g/cm3 when the Tm2O3 was raised from 0 wt% to 30 wt%. Likewise, with the addition of Dy2O3 compound, the densities of ceramics varied between 2.607 g/cm3 to 4.152 g/cm3. It was found that nuclear radiation shielding properties evolved by adding Tm2O3 and Dy2O3 compounds in the present ceramic.

Exploring critical behavioral differences in physical, structural, and nuclear radiation attenuation properties of produced High Entropy Alloy (HEA) and Refractory-High Entropy Alloy (RHEA) samples

Refractory-High entropy alloys (RHEAs) are known for their exceptional mechanical and radiation-resistant properties, making them promising materials for use in nuclear reactors. Their high entropy composition, which consists of multiple elements in roughly equal proportions, can create a stable microstructure that withstands high levels of radiation damage. The objective of this work is to further our comprehension of the unique behavioral, physical, structural, and nuclear radiation attenuation characteristics shown by High-Entropy Alloys (HEA) and Refractory-High entropy alloy (RHEA) materials. Accordingly, two high entropy alloy (HEA) samples through two different compositions were produced. The first composition under consideration is the typical high-entropy alloy (HEA) defined as MnCrFeNiCoMo0.5. The second composition under consideration is a refractory high entropy alloy (RHEA) characterized by the following elemental composition: TiZrNbHfVTa0.1. SEM and EDX analyses were conducted in terms of determining their physical and structural attributes. Next, a133Ba radioisotope together with a HPGe detector were utilized for gamma-ray transmission experiments. Finally, a241Am/Be source and a gas proportional detector were used for neutron absorption experiments for HEA and RHEA samples. The alloy structures displayed a unique degree of uniformity. Throughout the RHEA phase, the incorporation of refractory elements did not provide any discernible adverse impacts on the physical stability. The counting spectrum provided a clear explanation of the gamma ray absorption features shown by the RHEA (R) sample, highlighting its exceptional absorption properties. Regarding the absorption properties of neutrons, it was observed that RHEA had a comparatively reduced amount of absorption. Therefore, it can be concluded that the basic structure of RHEA grants it superior gamma-ray attenuation qualities compared to HEA. It can be concluded that RHEA demonstrates superior applicability as a material in comparison to HEA, especially in situations involving the use of fuel rods, where maintaining of neutron quantity has paramount importance for achieving optimum neutron activation.

Oxides dispersion-strengthened (ODS) FeCoNiCuZn high entropy alloys through different rare earth elements: Synthesis, structural, physical, and experimental radiation transmission properties

The oxide dispersoids within ODS alloys can act as sinks for radiation-induced defects, such as vacancies and dislocation loops, effectively reducing their mobility and preventing their accumulation. This property is crucial for HEAs employed in radiation-intensive environments, such as nuclear reactors. The objective of this research is to examine the impact of rare earth elements (REE) such as Y2O3, Er2O3, Pr2O3, and Sm2O3, on Oxides Dispersion-Strengthened (ODS) FeCoNiCuZn High Entropy Alloys (HEAs). The mechanical alloying technique is employed to produce a high entropy alloy consisting of Fe, Co, Ni, Cu, and Zn in their raw form. Subsequently, the raw alloy powder is enriched with separate amounts of Y2O3, Er2O3, Pr2O3, and Sm2O3. The microstructural analysis of the samples obtained from the mechanical alloying process was performed utilizing the X-ray diffraction (XRD) technique. In addition, scanning electron microscopy (SEM) was employed to analyze the ODS-HEA samples encoded S1, S2, S3, S4, and S5. To investigate the transmission properties of gamma-ray and neutron radiation, experimental studies are carried out using two types of detectors: Ultra High Purity Germanium (HPGe) detector and Canberra NP-100B BF3 gas proportional detector, respectively. The X-ray diffraction (XRD) spectra of samples did not display any observable peaks that could be attributed to the presence of dispersed rare earth element (REE) oxides. The uniform distribution of the metallic constituents that make up the High Entropy Alloy (HEA) is observed in the samples. Additionally, it can be observed that the implementation of the ODS-HEA technique, incorporating a 3% (wt.) Er2O3 additive, results in the most advantageous results with respect to the characteristics of gamma ray absorption. The S3 sample demonstrated the greatest degree of neutron absorption, as demonstrated by a recorded value of 0.857 μSv/h, where the S1 sample demonstrated the minimum level of absorption, as evidenced by a recorded value of 0.452 μSv/h. Based on the observed effects on neutron and gamma-ray attenuation behaviors in ODS-HEAs, it can be concluded that Er2O3 exhibits characteristics of a monotonic oxide. This feature is particularly advantageous for applications that necessitate a dual enhancement in these behaviors. It can also be concluded that the S1 sample may be deemed appropriate for situations where the utmost consistency of chain reactions in nuclear reactor fuel rods is desired, due to its possession of the lowest neutron absorption properties.

CdO-rich quaternary tellurite glasses for nuclear safety purposes: Synthesis and experimental gamma-ray and neutron radiation assessment of high-density and transparent samples

We present the preparation phase and comprehensive analysis of nuclear radiation shielding characteristics of novel melt-quenched 20P2O5·30TeO2.(50-x)ZnO.xCdO (x = 0, 15, 20, 30, and 40 mol percent) quaternary-tellurite glasses. The primary objective is to compare the changes in nuclear radiation absorption qualities that come from maintaining high transparency and increasing the CdO contribution rate to maximum values, such as 40 mol%. Consequently, experimental gamma-ray and neutron transmission systems are used to investigate the monotonic impacts of increasing CdO reinforcement on the functioning of synthesized glasses utilizing the well-known melt-quenching method. For the determination of attenuation coefficients, a standard gamma-ray setup is used with an Ultra germanium detector and 133Ba radioisotope. In addition, using the Canberra NP-100B BF3 gas proportional detector, glass shields are bombarded with a 241Am/Be neutron source (10 mCi/4.5 MeV) using a gas proportional detector. The addition of 40% mole CdO to the basic composition of glass significantly improved the transition resistance to gamma and neutron radiation. Furthermore, it was shown that the degree of transparency in the C40 sample synthesized with a 40% CdO additive ratio was equivalent to that of an ideal transparent glass sample. Moreover, C40 sample had better gamma-ray attenuation properties than all other shielding materials (except for RS-520). According to the findings, C glasses have a greater capacity for neutron attenuation than investigated conventional moderators. It can be concluded that C glass family is an effective gamma-shield and neutron moderator for research and medical radiation applications.

Synthesis and experimental characterization on fast neutron and gamma-ray attenuation properties of high-dense and transparent Cadmium oxide (CdO) glasses for shielding purposes

We present synthesis and thorough characterization phases of newly developed 20P2O5·30TeO2.(50-x)ZnO.xCdO (x = 0, 2, 4, 6, 8, 10 mol%) glasses. Experimental gamma-ray and neutron transmission systems are used in terms of exploring the monotonic effects of increasing CdO reinforcement on behavioural changes of synthesized glasses through well-known melt-quenching method. A conventional gamma-ray setup along with a high purity germanium detector as well as 133Ba radioisotope is used for determination of attenuation coefficients. Glass shields are irradiated with a241Am/Be neutron source using the Canberra NP-100B BF3 gas proportional detector. The addition of 10% mole CdO to the basic glass composition had a significant favorable impact on the transition resistance to gamma and neutron radiation. In comparison to all available shielding materials, (except RS-520), the C10 sample demonstrated superior gamma-ray attenuation capabilities. According to results, C glasses generally exhibit superior neutron attenuation capabilities than conventional moderators. It can be concluded that C glass family may be considered as suitable gamma-shield and neutron moderator in different types of applications from research to medical radiation fields.

A closer-look on Copper(II) oxide reinforced Calcium-Borate glasses: Fabrication and multiple experimental assessment on optical, structural, physical, and experimental neutron/gamma shielding properties

This study aimed to fabricate six different Copper(II) oxide reinforced Calcium-Borate glasses with different types of substitutions such as Al2O3/V2O5, BaO2/V2O5, and ZnO/V2O5. Accordingly, a depth characterization process has been performed for ACV, BCV and ZCV glasses with a nominal composition of 55B2O3–35CaO–9Al2O3-0.5CuO-0.5V2O5, 55B2O3–35CaO-8.5Al2O3-0.5CuO–1V2O5, 55B2O3–35CaO–9BaO2-0.5CuO-0.5V2O5, 55B2O3–35CaO-8.5BaO2-0.5CuO–1V2O5, 55B2O3–35CaO–9ZnO-0.5CuO-0.5V2O5, 55B2O3–35CaO-8.5ZnO-0.5CuO–1V2O5. Optical, structural, physical, and experimental neutron/gamma shielding properties of synthesized glasses were determined, respectively. Experiments measuring neutron exposure indicated how well glass samples attenuated fast neutrons. The RADACS software was used to record data from a BF3 gas proportional detector from the Canberra NP-100B series and a 241Am/Be neutron source with a 10 mCi activity. The absorption edge belonging to the samples are found between 420 nm and 480 nm. Our findings showed that the optical band gaps for the samples ranged from 1.179 to 2.022 eV. The wavenumber range of 400–1600 cm-1 was evaluated for the resulting peaks. The region with the highest band formation was approximately 760–1170 cm-1. While BCV0.5 and BCV1 glasses with 9% and 8.5% BaO2 insertion have the largest MAC values ranging between 2.255–0.076 and 2.156–0.076 cm2/g, the lowest MAC values varying between 0.361–0.0761 and 0.366–0.076 cm2/g belong to ACV0.5 and ACV1 glasses with 9% and 8.5% Al2O3 addition. Our results showed that the BCV glass family has superior material properties among the fabricated glasses. It can be concluded that BaO2/V2O5 glasses may be used in replacement of Copper(II) oxide glasses to provide monotonic behavior on crucial characteristics while maintaining the greatest density increase for large gamma ray shielding properties.

Investigation of neutron and gamma radiation protective characteristics of synthesized quinoline derivatives

Purpose Quinoline is formed by various natural compounds, such as alkaloids from the cinchona plant, which exhibit various biological activities, and is an important building material for the development of new drugs. Quinoline can be used in anti-radiation drug development but radiation interaction properties must be determined. Material and methods In this study, six types of synthesized quinoline derivatives were used. Fast neutron removal cross-section, mean free path, half value layer and transmission number were theoretically determined by using GEometry ANd Tracking 4 and FLUktuierende KAskade simulation codes for neutron shielding. Neutron dose absorption rates were determined using the 241Am-Be fast neutron source and the Canberra NP series portable BF3 gas proportional neutron detector. Gamma radiation shielding parameters were determined by using WinXCom and PSY-X/PSD software. Additionally, the genotoxic potentials of the derivatives were assessed by using the Ames/Salmonella bacterial reversion assay. Results and conclusions Neutron shielding parameters such as removal cross-section, mean free path, half value layer and transmission number were theoretically determined for fast neutrons. To determine neutron absorption capacity of quinoline derivatives, neutron absorption, experiments were conducted. In addition, gamma radiation shielding parameters were calculated such as the mean free path (MFP), mass attenuation coefficient (µt), half value thickness layer (HVL) and effective atomic number (Zeff) in the energy range of 0.015–15 MeV. The results of the all quinoline derivatives have excellent fast neutron shielding power compared to ordinary concrete. In addition, all quinoline derivatives have been found to have the capacity to attenuate gamma radiation. Moreover, they absorb well in both types of radiation, do not cause secondary radiation, and they are genotoxically safe at the tested concentrations. This study has demonstrated that these products can be used as active ingredients for a drug to be developed against radiation.

Effects of rain and soil moisture on background neutron measurements with the SuperMISTI neutron array

Background neutron measurements were recorded for approximately two months at Camp Blanding, FL, with a large array of moderated gas proportional detectors and EJ-309 liquid scintillator detectors. The variations in the local neutron background rate were on the order of 10% and were observed to be primarily due to the changing level of moisture in the local soil due to precipitation and evaporation. Simple models were constructed based only on very basic climatological information and were able to reproduce the major variations in our measured neutron counts with time. These simple models compare favorably to the more-complex modified Penman equation developed for the California Irrigation Management Information System. An accurate model to describe local neutron background variations based on easily measured climatological data would be invaluable to provide corrections for stationary neutron monitors.

10B+ZnS(Ag) as an alternative to 3He-based detectors for Radiation Portal Monitors

Typical radiation portal monitor systems, RPM, deployed to detect illicit trafficking of radioactive materials include a set of gamma-ray detectors and neutron detectors. Usually the employed neutron detectors are pressurized 3 He-based neutron detectors tubes. Due the shortage of 3 He reported since 2009, the amount of 3 He available for use in gas proportional counter neutron detectors has become limited, while the demand has significantly increased, especially for homeland security applications. For this reason, many different alternatives are being investigated for its use in RPM systems. The aim of this work is to study a scintillation detector ZnS(Ag) mixed with highly enriched 10 B, 10 B+ZnS(Ag). Using Monte Carlo methods, MCNPX code, the response of two neutron detectors based on 10 B+ZnS(Ag), manufactured by BridgePort Instruments LLC with different geometries, were estimated by calculating the number of 10 B(n,α)7 Li reactions for 29 monoenergetic neutron sources. Measurements and models were made, and both detectors were compared. The importance of the distance with respect to the ground was studied. The response with a 252 Cf moderated neutron source (0.5 cm lead and 2.5 cm polyethylene) was calculated in order to compare with other studied alternatives in the USA by Pacific National Northwest Laboratory, PNNL. With these results we conclude that neutron detectors using 10 B+ZnS(Ag) are an interesting alternative for replacing 3 He detectors. From the analysis with MCNPX we propose an improvement in the detector design.

Toward sufficient reduction of radio-impurities for 32Si sediment age dating

This project is focused on developing a geochronology tool enabling age dating of coastal marine sediments in the 100–1000 year age range. The technique employs the 32Si/32P radio-chronometer with an ultra-low-background gas proportional beta detector with a background count rate approaching 10 counts per day (cpd), which will require significant decontamination of radiogenic nuclides present in the original sediment samples. This paper describes the multiple physical and chemical separation methods employed to maintain a high final chemical yield of P while reducing the radiogenic contributions. The final purified 32P samples had, on average 100 ± 7 % chemical yields with no quantifiable gamma emissions present.

10B(n, Z) Measurements in the Energy Range 0.7 to 5.0 MeV

Four ΔE E telescopes were used at the WNR (n,Z) station to investigate the production of charged particles from 10B. The telescope consisted of a gas proportional detector and a silicon surface barrier detector. The flux was determined using a 235U fission chamber. A clear separation of the ground state alpha group and first excited state was not achieved due to the target thickness. Proton emission was also observed. The proton branch was up to an order of magnitude larger than predicted in ENDF/B-VII. A simple R-matrix analysis has been performed on the available data.

Establishment of a method for measurement of gross alpha/beta activities in water from Vojvodina region

Very important part of environmental studies is the determination of the quality of drinking water, which often requires measuring of alpha and beta activity in analyzed water samples. The usual method for monitoring of low-level α and β radioactivity is to use gas-proportional detectors where ionization and proportional regions are used for α and β counting, respectively Simultaneous measurement of gross alpha and gross beta activities by liquid scintillation counting technique using Quantulus 1220 liquid scintillation counter (LSC) equipped with Pulse Shape Analyzer (PSA) is described. Water samples were prepared for measurements according to the ASTM D 7283-06 Standard Test Method. More than 50 samples of drinking water from Vojvodina region were measured. The data obtained can provide important information for the consumer regarding the preliminary dose exposure risk due to water intake.

Experimental analysis of the mass efficiency curve for gross alpha activity and morphological study of the residue obtained by the co-precipitation method

Gross alpha activity determination in drinking water is one of the radiological parameters that must be determined in order to decide whether further specific analyses of radionuclides in samples is required. This parameter can be determined by the co-precipitation method using a ZnS(Ag) scintillation detector or a proportional counter. The method consists of collecting all alpha emitters of interest using barium and iron as carriers as they provide more uniform and homogeneous residues than the evaporation method, especially for highly saline waters. In the course of our work, the efficiencies of the gas proportional and ZnS(Ag) detectors for alpha particle detection in water residues were studied in function of sample mass (precipitate) with residues ranging between 16.0 and 35.0mg. In addition, the structure and morphological composition of a residue collected by the co-precipitation method was studied with the aim of verifying whether the residue is a homogeneous mixture. The effect of alpha energy on the efficiency and stability of the calibration samples (mass and efficiency) was studied using 230Th, natural uranium (natU) and 241Am radionuclides.

On Neutron Spectroscopy Using Gas Proportional Detectors Optimized by Transport Theory

We explore in this study the practical limits in designing a neutron detector array to resolve the spectra from special nuclear material (SNM) neutron sources using 3He detectors. We demonstrate that radiation transport analysis yielded a spectrum unfolding strategy based on the energy structure of the BUGLE-96 cross-section library, with 47 neutron energy groups. The initial computational model used is an isotropic planar source incident on a block of high-density polyethylene moderator. Assuming 3He is diluted throughout the moderator, the 3He(n,p) reaction rate energy group matrix in the block was computed using a completely “flat” neutron source spectrum. Analyzing the energy group matrix, there are neutrons from specific collections of energy groups (energy “bands”) that induce a maximum reaction rate in specific locations; we determined that these groups cannot be further differentiated within the energy band using 3He detectors. It was determined that optimal spectral fidelity for SNM detection and characterization is achievable using four spectral bands spanning among groups 1 through 29 (31.8 keV to 17.3 MeV). Using ideal-filter materials to remove the neutrons from different regions of the spectrum, we predicted the maximum neutron spectral resolution obtainable using this approach. To demonstrate our method, we present the optimally detected spectral differences between SNM materials (plutonium and uranium), metal and oxide, using ideal-filter materials. We have also selected a number of candidate filtering materials and, by replacing the ideal filters with real materials, we exemplified our approach with a design of a neutron detector array capable of resolving the spectra from SNM neutron sources using 3He detectors.

Simulation of spatial and energy resolution in signal for gas proportional detector

Computer simulations of charge transport and signal generation mechanism have been performed for the Aleph Inner Tracking Detector geometry. A number of factors influence the signal arising from the charge carriers generated within detector volume. In the present simulation, signal fluctuations due to changing of incident charged particle energy and position of the primary generated electron-ion pairs in the gas volume have been examined. The simulation calculations are in good agreement with experimental results. Key words: Signal generation mechanism, signal fluctuation, Monte Carlo device simulation.

Two-dimensional multiwire gas proportional detector for X-ray photon correlation spectroscopy of condensed matter

Details of a two-dimensional (2-D) multiwire gas proportional detector for X-ray photon correlation spectroscopy (XPCS) of condensed matter are described. The characteristics of the gas proportional detector at 8 keV, 0.3 pC anode charge, and 3 bar (absolute) of Xe/10%CO 2 are as follows: 8.5×10 −7 counts/s (100×100 μm 2) dark count rate, ∼μs time resolution, ∼48 and 73 μm position resolution (FWHM) along and across the anode wire direction, respectively, and ∼80% quantum efficiency. The effects of incident photon energy, anode charge (i.e., gain), gas drift depth, and gas pressure on position resolution are discussed. Static and dynamic speckle patterns, measured from disordered aerogel and polystyrene/polybutadiene blends by a partially coherent synchrotron X-ray source, demonstrate that a 2-D multiwire gas proportional detector is very suitable for the dynamic study of condensed matter with relaxation times in the order of μs to 10 3 s and atomic length scale.

Position resolution and energy spectra from a two-dimensional gas proportional detector in the region of the krypton K-edge

Results are presented of the position resolution and energy spectra from a two-dimensional gas proportional detector in the region of the krypton K-edge of 14.326 keV. Measurements were made with a gas mixture of Kr/10%CO 2 and the position resolution was fit by a simple model based on the photoelectron and Auger electron range. In the energy region below the K-edge, X-rays interact primarily in the L-shell, yielding an energetic photoelectron that limits position resolution to no better than several hundred μm. For X-rays with energy just above the K-edge, position resolution in the range of 90 μm FWHM was achieved using the technique of escape peak gating. We found broad low-level wings forming about 31% of the total area in the position spectrum above the K-edge, indicating that the L-shell interactions are included (and inseparable) in the gating technique of photopeak events within this energy range. Furthermore, the shape of the position spectrum was well explained when the energy dependence of σ L / ( σ K + σ L ) was considered above the K-edge.

High-resolution crystal spectrometer for the 10–60 Å extreme ultraviolet region

A vacuum crystal spectrometer with nominal resolving power approaching 1000 is described for measuring emission lines with wavelength in the extreme ultraviolet region up to 60 Å. The instrument utilizes a flat octadecyl hydrogen maleate crystal and a thin-window 1D position-sensitive gas proportional detector. This detector employs a 1-μm-thick 100×8 mm2 aluminized polyimide window and operates at one atmosphere pressure. The spectrometer has been implemented on the Livermore electron beam ion traps. The performance of the instrument is illustrated in measurements of the newly discovered magnetic field-sensitive line in Ar8+.

Modeling of alpha mass-efficiency curve

We present a model for efficiency of a detector counting gross α radioactivity from both thin and thick samples, corresponding to low and high sample masses in the counting planchette. The model includes self-absorption of α particles in the sample, energy loss in the absorber, range straggling, as well as detector edge effects. The surface roughness of the sample is treated in terms of fractal geometry. The model reveals a linear dependence of the detector efficiency on the sample mass, for low masses, as well as a power-law dependence for high masses. It is, therefore, named the linear-power-law (LPL) model. In addition, we consider an empirical power-law (EPL) curve, and an exponential (EXP) curve. A comparison is made of the LPL, EPL, and EXP fits to the experimental α mass-efficiency data from gas-proportional detectors for selected radionuclides: 238U, 230Th, 239Pu, 241Am, and 244Cm. Based on this comparison, we recommend working equations for fitting mass-efficiency data. Measurement of α radioactivity from a thick sample can determine the fractal dimension of its surface.

A versatile data acquisition system for time resolved X-ray scattering using gas proportional detectors with delay line readout

A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system.