Low Energy Gamma Research Articles

THE EXOGAM2 CALIBRATION USING THE NEWLY DEVELOPED NUMEXO2 DIGITAL ELECTRONIC

In this study, the calibration process of the EXOGAM2 conventional gamma detector system with the newly developed digital electronic device, namely NUMEXO2, will be presented. This experimental study was performed at the GANIL (Grand Accélérateur National d'Ions Lourds) nuclear research center in France. The energy calibration of the EXOGAM2 detector system with the newly developed NUMEXO2 digital electronic device was conducted using both low and high gamma energy levels of a 152Eu radioactive source. This calibration was carried out for two EXOGAM2 detectors, and the energy resolution of each crystal in the EXOGAM2 system was determined. 
 The energy resolution of each crystal was found to be reasonable energy resolution values of the EXOGAM2 detectors. Therefore, the use of the digital electronic device NUMEXO2 did not affect the energy resolution of the detectors, but it did enable us to acquire data at a high counting rate.

Evaluation of long-term robustness of the International System of Reference (SIR) used in radionuclide metrology based on the meta-analysis of its machine-readable database

In support of the CIPM MRA, the reference system in radionuclide metrology (SIR) is a unique experimental facility that has been able to provide continuous key comparison results for 72 radionuclides for 46 years. These measurement data are now available in a machine-readable format, which allows statistical analysis of these measurement results to be performed efficiently. Such a meta-analysis was conducted to verify whether or not the accumulated data confirmed the bold assumption made in the 1970s of the long-term robustness of the system over decades of operation. It was notably assumed that variation in the properties of the standard solution to be measured or the choice of the 226Ra reference source would have no impact on the measurement. For the majority of radionuclides measured by the SIR, the non-parametric significance tests of the null hypothesis carried out in this study gave no evidence, at the 95% confidence level, that the above statement should be reconsidered. However, this meta-analysis revealed a significant impact of solution density in the case of 109Cd, corroborating previous observations made in the case of 241Am where the robustness of an ionization chamber with respect to the density variation of the solution does not appear to be perfect. The extension of the SIR by a liquid scintillation system is under development. It will improve the robustness of international comparison results for those borderline cases where radionuclides emit only low-energy x-rays or gamma rays (<100 keV).

A Compact Particle Detector for Space-Based Applications: Development of a Low-Energy Module (LEM) for the NUSES Space Mission

NUSES is a planned space mission aiming to test new observational and technological approaches related to the study of relatively low-energy cosmic rays, gamma rays, and high-energy astrophysical neutrinos. Two scientific payloads will be hosted onboard the NUSES space mission: Terzina and Zirè. Terzina will be an optical telescope readout by SiPM arrays, for the detection and study of Cerenkov light emitted by Extensive Air Showers generated by high-energy cosmic rays and neutrinos in the atmosphere. Zirè will focus on the detection of protons and electrons up to a few hundred MeV and to 0.1–10 MeV photons and will include the Low Energy Module (LEM). The LEM will be a particle spectrometer devoted to the observation of fluxes of relatively low-energy electrons in the 0.1–7-MeV range and protons in the 3–50 MeV range along the Low Earth Orbit (LEO) followed by the hosting platform. The detection of Particle Bursts (PBs) in this Physics channel of interest could give new insight into the understanding of complex phenomena such as eventual correlations between seismic events or volcanic activity with the collective motion of particles in the plasma populating van Allen belts. With its compact sizes and limited acceptance, the LEM will allow the exploration of hostile environments such as the South Atlantic Anomaly (SAA) and the inner Van Allen Belt, in which the anticipated electron fluxes are on the order of 106 to 107 electrons per square centimeter per steradian per second. Concerning the vast literature of space-based particle spectrometers, the innovative aspect of the LEM resides in its compactness, within 10 × 10 × 10 cm3, and in its “active collimation” approach dealing with the problem of multiple scattering at these very relatively low energies. In this work, the geometry of the detector, its detection concept, its operation modes, and the hardware adopted will be presented. Some preliminary results from the Monte Carlo simulation (Geant4) will be shown.

Comparison of niobium-93m results obtained by two independent destructive analytical procedures and measured by low energy gamma spectrometry and liquid scintillation counting

Comparison of niobium-93m results obtained by two independent destructive analytical procedures and measured by low energy gamma spectrometry and liquid scintillation counting

Investigation of shielding properties of gamma and neutrons in some natural radioprotective drugs

In radiation therapy, various radioprotective materials are used to protect normal cells from damage due to ionizing radiation. Natural products such as apigenin, bergenin, caffeine, chlorogenic acid, coniferyl aldehyde, curcumin, delphinidine, and quinic acid have been found to be good radioprotectors as they have low toxicities. In order to select the best natural radioprotector, it is essential to understand the interaction of gamma and neutrons with these radioprotectors and to determine radiation shielding parameters. The radiation parameters such as mass attenuation coefficient (MAC), effective atomic number (Zeff), equivalent atomic number (Zeq), effective electron density (Neff), exposure buildup factor (EBF), and energy absorption buildup factor (EABF) have been determined for the natural radioprotectors using EpiXs and NGCal software. The estimated results show that the Zeff values of selected radioprotectors are higher in the low-energy region and lower in the high-energy region, indicating that they are suitable for shielding low-energy gamma photons. Among selected natural radioprotectors, quinic acid is the best radioprotector for shielding thermal and fast neutrons. The relationship between MAF and Zeff/Neff has been established for the first time, and it has been found that MAF for thermal and fast neutrons decreases with an increase in the Zeff/Neff values of selected natural radioprotectors.

An easy tool for the Monte Carlo simulation of the passage of photons and electrons through matter

A simple Monte Carlo (MC) algorithm for the simulation of the passage of low-energy gamma rays and electrons through any material medium is presented. The algorithm includes several approximations that accelerate the simulation while maintaining reasonably accurate results. Notably, pair production and Bremsstrahlung are ignored, which limits the applicability of the algorithm to low energies (≲5MeV, depending on the medium). Systematic comparisons for both photons and electrons have been made against the MC code PENELOPE and experimental data to validate the algorithm, showing deviations in the deposited energy smaller than or around 10% in the energy interval of 0.1–5 MeV in light media. The simulation is also valid for heavy media, but with less accuracy as a consequence of the abovementioned approximations. Also X-ray fluorescence is ignored leading to some limitations for photons with energies slightly over the K-shell. The algorithm has been implemented in an open-source Python package called LegPy, which provides an easy-to-use framework for rapid MC simulations aiming to be useful for applications that do not require the level of detail of available well-established MC programs.

Thin-film assembly via encapsulation of nano-aluminum oxide-linked-pb(II)-2,4-dinitroaniline complex into a polymeric matrix as efficient radiation shielding materials

Radiation safety and protection is a subject of major concern for all communities because of the biological damage caused by different radiation sources. Therefore, the purpose of this study is aimed to synthesize two different thin films from a newly synthesized N-Al2O3@Pb(II)-2,4-DiNA nanocomposite which was prepared by the direct chemical coupling of nano-aluminum oxide (N-Al2O3) with Pb(II)-2,4-dinitroaniline complex. The synthesized materials were characterized by FT-IR, thermogravimetric analysis (TGA), scanning electron microscope SEM, and elemental composition by energy-dispersive X-ray (EDX). The two thin films were assembled by the encapsulation of N-Al2O3@Pb(II)-2,4-DiNAnanocompositeinto hydrolyzed polyurethane and hydrolyzed polyvinyl chloride. Electron spin resonance (ESR) measurements have been used to investigate the newly prepared nanocomposite and thin films before and after gamma irradiation. Gamma spectroscopy, Phy-X software, and SRIM (stopping and range of ions in matter) Monte Carlo simulation code are aimed to apply and investigate radiation shielding efficiency of films for gamma/x-ray, protons, alpha, and thermal neutrons. The gamma shielding characteristics, mass stopping power (MSP), and range for both proton (H-ions) and alpha (He-ions) were also calculated. In addition, the SRIM code’s subroutine TRIM was used to predict the damage production and atomic displacements per atom (dpa) caused by the interaction of high-energy H-ions (proton) and He-ions (alpha) with the studied samples. The data obtained the good radiation shielding effect of the prepared thin films and their possible use as radiation shielding materials for X-rays and low gamma energy.

Phantom study of layered sensor module for photon-counting BMD detector.

In this study, we perform bone mineral density (BMD) calculation by designing a layered sensor module (LSM) that divides high- and low-energy spectra from a single shot of X-rays. Gamma-ray evaluation supports this mechanism; low-energy gamma rays are absorbed in the front detector, whereas high-energy gamma rays are absorbed in the rear detector. In this phantom study, LSM divides a single shot of X-ray into two spectra with different distributions of energy, thereby affording X-ray images with different properties, such as contrast and gray scale. The region of interest (ROI) is classified by the Prewitt operator to sort the pixels for BMD calculation or Rs value. The calculated final value is 1.2051g/cm2 with a standard deviation (SD) of 0.3690g/cm2, as obtained from our previous study. An improved SD results from the layered structure with two channels for signal processing, the introduction of Rs value, and the use of Prewitt filter to sort reliable data. Overall, this study displays the feasibility of LSM for BMD calculation with a small error, thereby enabling the diagnosis of osteoporosis with novel mechanism.

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.

Synthesis and characterization of Lead–Nickel–Boron nanocomposite for radiation shielding application

We have synthesized the Lead–Nickel–Boron (LNB) nanocomposite using Green synthesis approach for the first time. LNB is synthesized by solution combustion method using Alovera as a reducing agent. The released combustion products do not affect the environment to a greater extent resulting in less air pollution compared to that of chemical synthesis. The synthesized nanocomposite is characterized using various techniques such as PXRD, SEM, UV–Vis and FTIR spectroscopy. The non-spherical shape of the nanocomposite has been confirmed through SEM images. XRD & FTIR studies reveal the physical and chemical structure of the compound. Both experimental and theoretical approach were used to study the gamma shielding ability of the nanocomposite and its efficiency is comparable to that of pure lead. The value of mass attenuation coefficient of the LNB nanocomposite is found to be 0.44, 0.36, 0.13, 0.10, 0.06, 0.06 cm2/g for 0.276, 0.356, 0.511, 0.661, 1.173 and 1.332 MeV gamma rays. Highest attenuation coefficient and lowest HVL (half value layer-the thickness of any given material where 50% of the incident energy has been attenuated) values are observed at 0.276MeV gamma ray energy. Thus proving excellent efficiency in attenuating low energy gamma rays. It is evident from the results of high neutron absorption cross section and scattering length of value 8.5fm which is comparable to that of Lead. Thus, LNB nanocomposite has also proved to be efficient in absorbing neutrons as well as Bremsstrahlung radiation and neutron shielding efficiency is better than that of lead thus acting as a good neutron absorber. Hence, LNB nanocomposite is efficient and environmental friendly material which can absorb multiple radiations like X/Gamma rays, neutrons and Bremsstrahlung radiation.

Machine learning method for 12C event classification and reconstruction in the active target time-projection chamber

Active target time projection chambers are important tools in low energy radioactive ion beams or gamma rays related researches. In this work, we present the application of machine learning methods to the analysis of data obtained from an active target time projection chamber. Specifically, we investigate the effectiveness of Visual Geometry Group (VGG) and the Residual neural Network (ResNet) models for event classification and reconstruction in decays from the excited 22+ state in 12C Hoyle rotation band. The results show that machine learning methods are effective in identifying 12C events from the background noise, with ResNet-34 achieving an impressive precision of 0.99 on simulation data, and the best performing event reconstruction model ResNet-18 providing an energy resolution of σE<77 keV and an angular reconstruction deviation of σθ<0.1 rad. The promising results suggest that the ResNet model trained on Monte Carlo samples could be used for future classifying and predicting experimental data in active target time projection chambers related experiments.

SYNTHESIS AND CHARACTERIZATION OF OPTICAL, STRENGTH AND SHIELDING CHARACTERISTICS OF 0.6TeO&lt;sub&gt;2&lt;/sub&gt;-0.25BaO-0.15ZnO

This study presents the results of studying the optical, strength, dielectric and screening characteristics of 0.6TeO20.25BaO-0.15ZnO glasses. The method of mechanochemical grinding of the initial oxide components followed by thermal sintering in order to obtain vitreous samples with an amorphous structure was chosen as the preparation method. To characterize the obtained samples, the methods of scanning electron microscopy, energy dispersive analysis, X-ray diffraction, impedance and optical spectroscopy were used, and the strength properties were determined using the indentation method. In the course of the studies of the structural features and phase composition, it was found that the synthesized glasses have an amorphous nature, with a small content of inclusions in the form of BaZnTe2O7 grains. At the same time, the analysis of the mapping of elements in the glass composition showed an isotropic distribution of all components in the glass composition and the complete absence of any impurities. When determining the optical properties of the synthesized glasses, it was found that the transmission spectra contain a wide absorption band in the visible light region, as well as three spectral absorption bands characteristic of oxygen vacancies and interstitial oxygen atoms. According to the data of strength characteristics, it was found that the synthesized glasses have sufficient hardness and resistance to external influences, and the nature of crack formation is typical for semi-disk cracks. An analysis of the shielding characteristics of the synthesized glasses showed high efficiency in shielding low-energy gamma rays.

Assaying of SNM using Simultaneous Detection of Fission Neutrons and Gammas by Employing a Novel Phoswich Detector

For the precise measurements of special nuclear materials (SNM) including Pu and Am isotopes, we have used phoswich detector combination of two single crystal scintillators of Gd3Ga3Al2O12:Ce and CsI:Tl. High detection efficiency and sensitivity along with high figure of merit for the discrimination of these phoswich detectors ensures the detection and discrimination of thermal neutrons and gammas from spontaneous fission of Pu and other isotopes in presence of high gamma background. Using this detector, the low energy gammas, which is stopped completely in 1mm thick disc of GGAG, can be also discriminated from high energies gamma and shows linearity in wide range of sample quantities. By changing only the appropriate shielding, the similar setup was used for thermal neutron detection and shows a very good linearity over wide range. The quantity of a test sample was also calculated accurately by using the measured calibrated plot.

Assessment of Silicone Rubber/Lead Oxide Composites Enriched with Bi2O3, WO3, BaO, and SnO2 Nanoparticles for Radiation Shielding Applications.

This study aimed to prepare silicone rubber composites with heavy metal oxide nanoparticles for gamma ray shielding applications. Different heavy metal oxide nanoparticles were incorporated into the silicone rubber matrix, and the prepared composites were characterized for their thermal, mechanical, and radiation shielding properties. The density of the prepared SR samples ranged from 1.25 to 2.611 g·cm-3, with SR-2 having the highest density due to the presence of lead oxide. Additionally, the thermal stability of the materials improved with the addition of HMO nanoparticles, as indicated by TGA results. The prepared SR materials showed ultimate deformation displacement ranging from 14.17 to 21.23 mm, with the highest value recorded for SR-3 and the lowest for SR-2. We investigated the transmission factor (TF) of gamma rays through silicone rubber (SR) composites with different heavy metal oxide (HMO) nanoparticles. The addition of HMOs resulted in a decrease in TF values, indicating improved radiation shielding performance. The TF was found to be lowest in SR-5, which contained 15% of Bi2O3, WO3, BaO, and Zr2O3 each. The linear attenuation coefficient (LAC) of the SR samples was also evaluated, and it was found that the incorporation of HMOs increased the probability of photon interactions, leading to improved radiation protection effectiveness. The half-value layer (HVL) of the SR samples was also examined, and it was found that the addition of HMOs resulted in a significant reduction in HVL values, particularly at low energy levels. SR-5 had the lowest HVL among the group, while SR-2, SR-3, and SR-4 had higher HVL values. These results demonstrate the effectiveness of using HMOs in enhancing the radiation shielding properties of SR composites, particularly for low-energy gamma rays.

Study of the matrix composition effect on gamma spectrometry analysis using Monte Carlo simulation: application for soil to crop transfer factor determination

Abstract Self-absorption effect has a significant impact on gamma spectrometry measurement for the highly precise determination of the radionuclides activity. Among the main factors affecting the self-absorption effect especially at low gamma energies is the matrix composition of the sample. For this purpose, we studied the matrix composition effect on the self-absorption correction for plant and soil matrices using a Monte Carlo simulation model, composed of High Purity Germanium (HPGe) detector and a cylindrical geometry source. The simulated configuration model was validated by comparison of simulated full energy peak efficiency (FEPE) values with the experimental ones using a standard radioactive solution, covering large interval gamma energies in the range of 59.54–1836.12 keV. The results show that the FEPE values of low gamma energies are affected by the matrix composition, where in the soil matrix the FEPEs decreased by 36% and only by 1% in the plant matrix. The Monte Carlo results were applied in order to accurately calculate the transfer factor of the environmental radionuclides 226Ra, 232Th and 40K from soils to several crops, mustard, artichoke and fennel through their specific activities.

ОПРЕДЕЛЕНИЕ УДЕЛЬНОЙ АКТИВНОСТИ 177Lu И СОПУТСТВУЮЩИХ РАДИОНУКЛИДНЫХ ПРИМЕСЕЙ

Radioactive isotopes of rare earth elements (REE) are increasingly used in nuclear medicine for diagnostic and therapeutic purposes as they have effective nuclear physical properties. Seventeen elements of the secondary subgroup of group III of the periodic table of chemical elements of D.I. Mendeleev with atomic numbers 21, 39, 57, 58-71: scandium, yttrium, lanthanum and 14 lanthanides make up rare earth elements. Every year more and more attention is paid to the radioactive isotope of lutetium 177Lu, the most promising for use in therapeutic agents of a new generation, including for cell therapy of oncological diseases. The advantages of 177Lu are determined by its nuclear characteristics: the optimal depth of penetration into human tissues during radiotherapy of small tumors and low radiation load on healthy organs are provided due to the maximum energy of beta radiation of 496 keV, the presence of low-energy gamma radiation of 113 keV allows monitoring the treatment process, the half-life of 6.71 days makes it possible to transport drugs from 177Lu to significant distances.

A scanning focus nuclear microscope with multi-pinhole collimation

Microscopic nuclear imaging down to spatial resolutions of a few hundred microns can already be achieved using low-energy gamma emitters (e.g. 125I, ∼30 keV) and a basic single micro-pinhole gamma camera. This has been applied to in vivo mouse thyroid imaging, for example. For clinically used radionuclides such as 99mTc, this approach fails due to penetration of the higher-energy gamma photons through the pinhole edges. To overcome these resolution degradation effects, we propose a new imaging approach: scanning focus nuclear microscopy (SFNM). We assess SFNM using Monte Carlo simulations for clinically used isotopes. SFNM is based on the use of a 2D scanning stage with a focused multi-pinhole collimator containing 42 pinholes with narrow pinhole aperture opening angles to reduce photon penetration. All projections of different positions are used to iteratively reconstruct a three-dimensional image from which synthetic planar images are generated. SFNM imaging was tested using a digital Derenzo resolution phantom and a mouse ankle joint phantom containing 99mTc (140 keV). The planar images were compared with those obtained using a single-pinhole collimator, either with matched pinhole diameter or with matched sensitivity. The simulation results showed an achievable 99mTc image resolution of 0.04 mm and detailed 99mTc bone images of a mouse ankle with SFNM. SFNM has strong advantages over single-pinhole imaging in terms of spatial resolution.

Hierarchical Self-Assembly in DNA Ionogel: Effect of γ-Radiation on Gel Properties

DNA ionogels prepared by adding 1-ethyl-3-methylimidazolium chloride on low energy gamma irradiated DNA solution samples reveal non-trivial self-assembly. Variations in secondary structure and low-frequency gel rigidity modulus G0 captured this unique hitherto unexplored features of these gels. Interestingly, at higher radiation dose (0 to 100 Gy) samples could partially lose their initial rigidity. Dynamic light scattering revels dose dependent relaxation dynamics corresponding to ergodicity breaking time. In particular, viscosity and rheology showed that the time of gelation tgel, temperature of gelation Tgel and strength of gelation G0 are gamma ray dose dependent. DNA Ionogel melting with temperature shows self-assembled characteristics of this biomaterial. Gelation kinetics of ionizing radiation treated DNA strands have been studied in literature.

Use of Compton suppression gamma ray spectrometry to determine 239Pu

239Pu has been characterized by gamma-ray spectroscopy for a level higher than the usual environmental ones typically needing alpha spectrometry, ICP-MS or TIMS. The higher activities typically have applications in reprocessing, safeguards verification, and nuclear forensics. For activities of hundreds of Bq/g, it is possible to use gamma ray spectrometry for 239Pu characterization. A soil reference standard of 185 Bq/g (75 ng/g) was measured on a 79% efficient HPGe with a digital Compton suppression system. The ratios of the counting statistics for suppressed and unsuppressed uncertainties for various 239Pu photopeaks were determined. The effects of self-attenuation on the low energy gamma rays were evaluated, and it was determined that Compton suppression was an effective characterization method of 239Pu after accounting for self-attenuation.

The NUSES space mission

NUSES is a new space mission aiming to test innovative observational and technological approaches related to the study of low energy cosmic and gamma rays, high energy astrophysical neutrinos, Sun-Earth environment, Space weather and magnetosphere-ionosphere-lithosphere coupling (MILC). The satellite will host two payloads, named TERZINA and ZIRÉ. ZIRÉ will perform measurements of electrons, protons and light nuclei from few up to hundreds of MeV, also testing new tools for the detection of cosmic MeV photons, and monitoring of MILC signals. TERZINA will observe the Cherenkov light produced by EAS generated by cosmic ray primaries at very high energies and will monitor the light emissions from the Earth limb in the near UV and visible ranges at the ns time scale, thus testing the observational concept of detecting Earth skimming astrophysical high energy neutrinos. The scientific objectives and development status of the mission will be presented.