Radioactive Decay Research Articles

Excitation functions of72Ge(p,xn)72,71As reactions from threshold up to 45 MeV for production of the non-standard positron emitter 72As

Nuclear reaction cross sections for the formation of 72As and 71As in proton-induced reactions on enriched 72Ge targets were measured up to 45 MeV utilizing three different cyclotrons at the Forschungszentrum Jülich. The stacked-thin sample activation technique in combination with high-resolution γ-ray spectrometry was used. The major γ-ray peaks of 72As and 71As formed via the 72Ge(p,n)72As and 72Ge(p,2n)71As reactions, respectively, were analyzed. The incident proton energy and flux on a foil were determined using several monitor reactions. Based on integrated counts, irradiation data and the nuclear decay data, the reaction cross sections were measured. All data describe the first measurements. Theoretical nuclear model calculations were then carried out by using the codes TALYS 1.96, EMPIRE 3.2 and ALICE-IPPE. A very good agreement between the measured data and calculated values was found. The new data enabled us to calculate the thick target yields and estimate the radionuclidic impurities for a given energy range. Over the optimum energy range Ep = 14 → 7 MeV, the calculated thick target yield of 72As amounts to 272 MBq/μAh with no 71As impurity at all. The 72Ge(p,n)72As reaction on the enriched 72Ge is thus very suitable for clinical scale production of 72As at a medical cyclotron.

A Generic Implementation of the D1S Methodology for Dose Rate Assessment by Monte Carlo Codes in Fusion Applications

Dose rate assessment is of utmost importance in fusion reactors because of the maintenance operations that these facilities will require. The standard way to perform this assessment in ITER is use of the Direct 1-Step (D1S) methodology, which consists of performing neutron transport simulation, material activation, and decay photon transport simulation in one step and thus in one simulation only. Usually, implementation of the D1S methodology requires changing the source files in a reference Monte Carlo code. The purpose of the present work is to develop an easy-to-implement method for Monte Carlo codes to help calculate the dose rate in fusion reactors. To do so, the proposal is to act on nuclear data only and not on source files of the simulation codes. This is done by replacing prompt photon production in evaluation files by suitable decay photon production, taking into account radioactive decays of radionuclides and irradiation history. This study was to be applied first on the TRIPOLI-4® Monte Carlo code for the sake of simplicity. TRIPOLI-4 is the reference code for particle transport at CEA. The verification and validation process relies first on a comparison to the reference Rigorous 2-Step (R2S) methodology and then on an experiment, the so-called Frascati Neutron Generator (FNG) dose experiment. The nuclear database to be changed is of the ENDF-6 format, a recurrent format in neutronics studies. The analysis studied both neutron and photon responses to check if the simulation was performing normally in a physical way and to compare the results with references provided by simulations based on the R2S methodology or by the FNG dose experiment. The simulations have proven to be in good agreement with the experimental results.

Kilonova light-curve interpolation with neural networks

Kilonovae are the electromagnetic transients created by the radioactive decay of freshly synthesized elements in the environment surrounding a neutron star merger. To study the fundamental physics in these complex environments, kilonova modeling requires, in part, the use of radiative transfer simulations. The microphysics involved in these simulations results in high computational cost, prompting the use of emulators for parameter inference applications. Utilizing a training set of 22 248 high-fidelity simulations (composed of 412 unique ejecta parameter combinations evaluated at 54 viewing angles), we use a neural network to efficiently train on existing radiative transfer simulations and predict light curves for new parameters in a fast and computationally efficient manner. Our neural network can generate millions of new light curves in under a minute. We discuss our emulator's degree of off-sample reliability and parameter inference of the AT2017gfo observational data. Finally, we discuss tension introduced by multiband inference in the parameter inference results, particularly with regard to the neural network's recovery of viewing angle. Published by the American Physical Society 2024

Recommended Nuclear Structure and Decay Data for A=202 Isobars

Evaluated nuclear structure and decay data for all nuclei with mass number A=202 (202Os, 202Ir, 202Pt, 202Au, 202Hg, 202Tl, 202Pb, 202Bi, 202Po, 202At, 202Rn, 202Fr and 202Ra), are presented. All available experimental data are compiled and evaluated, and best values for level and γ-ray energies, quantum numbers, lifetimes, γ-ray intensities and transition probabilities, as well as other nuclear properties, are recommended. Inconsistencies and discrepancies that exist in the literature are discussed. A number of computer codes (https://www-nds.iaea.org/public/ensdf_pgm/) developed by members of the NSDD network were used during the evaluation process. This work supersedes the earlier evaluation by F.G. Kondev (2007Ko42), published in Nuclear Data Sheets108, 1471 (2007).

Approach to startup inventory for viable commercial fusion power plant

With the increasing efforts to commercialize fusion power, private and government organizations are investing heavily in the development of technology to support a viable fusion power plant. Deuterium-Tritium (DT) fueled reactors are more prevalent than other proposed designs, requiring tritium processing and handling technology for safe operations and self-sufficiency. Further, each fusion power plant will need a specific-to-design startup inventory of tritium to begin operations. This startup inventory is required prior to breeding and is the minimum tritium inventory required to fill each processing component in the fuel cycle, to offset radioactive decay losses, and to avoid a zero-fuel situation for continuous operation. We present an approach to calculate the startup tritium inventory for a 500 MWth reactor, with considerations for reserve inventory for maintenance and commissioning. A baseline startup inventory was calculated to be approximately 327 gs. This value was obtained using modest assumptions about the technology and operating parameters of a fusion power plant. The required operating reserve inventory or the inventory necessary to keep a fusion power plant operational using only direct internal recycling for 24 h for the same plant design is approximately 642 gs. The approach and findings of this paper will enable fusion energy stakeholders to better utilize the existing scarce global tritium supply.

Radioactive Attenuation Using Different Types of Natural Rocks.

Humans benefit from nuclear technology, but it also generates nuclear radiation that is bad for both the environment and human health. The serious issue of radiation leakage affects many technological applications. Shielding is required to protect both users and the environment from negative side effects. This work describes the radioactive attenuation properties of some natural rocks, such as claystone, bentonitic claystone, bentonitic shale, sandstone, and basalt using a NaI(Tl) detector. The mass attenuation coefficients μm of these rocks at various photon energies, half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) were determined. The validation of obtained values of μm was carried out against the theoretical calculations from the XCOM program, and the correlation factor and relative deviation between the two methods were evaluated. It was noted that basalt samples exhibit superior shielding parameters when compared to other rock samples. Also, the concentrations of naturally occurring radioactive elements (238U, 226Ra, 232Th, and 40K) were measured, allowing for the calculation of environmental hazard indices and assessment of attenuation (%) efficiency for certain natural rocks, such as bentonite, sandstone, and basalt. The results revealed that increasing the thickness of Basalt-AZ from 1.5 cm to 2 cm results in an approximate 11% rise in attenuation percentage, with values reaching 77.12%, 67.2%, 67.65%, and 59.8% for NMA-U, IAEA-Th, IAEA-Ra, and IAEA-K, respectively.

Measurement of the Isolated Nuclear Two-Photon Decay in ^{72}Ge.

The nuclear two-photon or double-gamma (2γ) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the 2γ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to ∼100 keV and half-lives as short as ∼10 ms. The half-life for the 2γ decay of the first-excited 0^{+} state in bare ^{72}Ge ions was determined to be 23.9(6)ms, which strongly deviates from expectations.

Nuclear Decay Detected in the Recoil of a Levitating Bead

Nuclear Decay Detected in the Recoil of a Levitating Bead

Performance of gas electron tracking detectors for beta decay studies

At the low-energy frontier, among the experiments testing the Standard Model and searching for new physics, are precision spectrum shape and correlation coefficient measurements in nuclear and neutron beta decay. For identification and 3D-tracking of low-energy electrons, a special type of gas-based detector was designed that minimizes scattering and energy loss. First, the newly developed gas tracker was successfully used to study tiny effects in the beta spectrum shape for allowed Gamow-Teller transitions. The miniBETA spectrometer consists of a hexagonally structured multi-wire drift chamber (MWDC) filled with a mixture of helium and isobutane gas and a plastic scintillator serving as a trigger source and energy detector. The drift time information is used to establish the electron tracks in the plane perpendicular to the wires, while the charge division technique provides spatial information along the wires. Second, inspired by the performance of this spectrometer we are building a Mott polarimeter to be used in the BRAND experiment to study the neutron decay correlation coefficients.

Field Detection of Uranyl in Coastal Water of China Using a Portable Device via DNA Photocleavage.

The urgent need for field detection of uranium in seawater is 2-fold: to provide prompt guidance for uranium extraction and to prevent human exposure to nuclear radiation. However, current methods for this purpose are largely hindered by bulky instrumentation, high costs of developed materials, and severe matrix interferences, which limit their further application in the field. Herein, we demonstrated a portable and label-free strategy for the field detection of uranyl in seawater based on the efficient photocleavage of DNA. Further experiments confirmed the generation of ultraviolet (UV) light-induced reactive oxygen species (ROS), such as O2•- and •OH, which fragmented oligomeric DNA in the presence of uranyl and UV light. Detailed studies showed that DNA significantly enhances uranyl absorption in the UV-visible region, leading to the generation of more ROS. A fluorescence system for the selective detection of uranyl in seawater was established by immobilizing two complementary oligonucleotides with the fluorescent dye SYBR Green I. The strategy of UV-induced photocleavage offers high selectivity, excellent interference immunity, and high sensitivity for uranyl, with a detection limit of 6.8 nM. Additionally, the fluorescence can be visually detected using a 3D-printed miniaturized device integrated with a smartphone. This method has been successfully applied to the on-site detection of uranyl in seawater in 18 Chinese coastal cities and along the coast of Hainan Island within 3 min for a single sample. The sample testing and field analysis results indicate that this strategy has promising potential for real-time monitoring of trace uranyl in China's coastal waters. It is expected to be utilized for the rapid assessment of nuclear contamination and nuclear engineering construction.

Preparation and radiation shielding features of high density, transparent borosilicate glasses with different Bi2O3 contents

This work assessed highly effective bismuth borosilicate glasses' nuclear radiation shielding capabilities in terms of different concentrations of Bi2O3. Melt-quenching was the method used to create the glasses. The Phy-X/PSD program was used to compute the μm values. The bismuth borosilicate glasses' nuclear radiation shielding properties were determined in the 0.015–15 MeV energy range. Increasing Bi₂O₃ concentration resulted in an increase in mass attenuation coefficient, linear attenuation coefficient, and effective atomic number. Conversely, the half value layer and mean free path values decreased. The B48Bi17 sample, with its largest Zeff, is a great gamma attenuator. The results of a new study may help to clarify the nature of the Bi2O3 additive used in borosilicate glasses, which are a potential form of shield for use in industrial and medical radiation facilities.

BaO-doped Na2O–CaO–P2O5 bioactive glasses: A closer look at radiation attenuation properties for medical applications

This study investigates the nuclear radiation attenuation characteristics of bioactive glasses with the system (26-x)Na2O-xBaO-29CaO–45P2O5, where x represents the molar percentage of BaO (0, 5, 10, 15). For this purpose, several parameters of shielding gamma radiation, such as the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), effective atomic number (Zeff), effective electron density (Neff), atomic cross-section (ACS), electronic cross-section (ECS), equivalent atomic number (Zeq), and transmission factor (TF) were calculated. The calculations were performed across different photon energy ranges (0.015–15 MeV) using Phy-X/PSD software and validated using the WinXCOM program. The results obtained from both the software platforms exhibited a high degree of agreement. Among the investigated glasses, the BNCP-15 glass, which had the highest BaO concentration, demonstrated the highest values for MAC, LAC, Zeff, Neff, ACS, ECS, and Zeq, while displaying the minimum values for HVL, TVL, MFP, and TF. For example, the LAC values at 15 MeV were found to be 0.056, 0.063, 0.070, and 0.077/cm for BNCP-0, BNCP-5, BNCP-10, and BNCP-15, respectively. Consequently, the BNCP-15 glass exhibited superior radiation attenuation performance in comparison to the other BNCP glasses examined in this study.

Distribution of Radiation-Induced Defects in Quartz at the ACKIO Uranium Prospect, Athabasca Basin, Saskatchewan: Tracing Uranium-Bearing Fluids

Abstract Quartz grains from the ACKIO uranium prospect, located near the eastern margin of the Athabasca Basin, Saskatchewan, have been investigated using powder X-band electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of quartz separates from samples systematically collected from the Athabasca Supergroup sandstones and the underlying metamorphosed basement reveal a suite of silicon-vacancy hole centers, which were formed by the bombardment of alpha particles emitted from the radioactive decay of uranium, thorium, and their unstable progeny. The differences in EPR signal intensities of these hole centers indicate that quartz grains received different accumulative doses of alpha particle irradiation in different locations within the ACKIO prospect. For example, quartz extracted from a mineralized sample has the highest EPR signal intensity due to the presence of disseminated uraninite. For quartz sampled at distance from uranium mineralization, the elevated intensities of the silicon-vacancy hole centers most likely indicate a temporary source of radiation, such as ancient uranium-bearing fluids. The median EPR intensities of quartz from the basement rocks at ACKIO are an order of magnitude higher than those of its counterpart from the Athabasca sandstones. Also, the EPR intensities of quartz along the sandstone–basement contact at ACKIO differ by more than two orders of magnitude, suggesting limited migration of uranium-bearing fluids along this contact in the study area. Instead, anomalously high EPR intensities in quartz close to the sandstone–basement contact and elsewhere are restricted to fault gouges and brecciated areas, suggesting that they are the structural pathways for channelized migration of ancient uranium-bearing fluids. A three-dimensional distribution model of the EPR signal intensities has been constructed to define conduits for the migration of ancient uranium-bearing fluids at ACKIO and suggest favorable targets for further exploration. These findings demonstrate the power of EPR spectroscopy in delineating pathways of uranium-bearing fluids and predicting potential mineralization targets.

A Comprehensive study on the γ-ray shielding performance of Al–Cu–PbO alloy: Experimental and simulation studies

The importance of radiation shielding is increasing due to the expanding areas exposed to radiation emissions. As a result, there is a crucial need to develop metal alloys and composites that demonstrate exceptional capabilities in absorbing neutron and gamma rays for effective radiation protection. The major purpose of this study is to determine the gamma photon attenuation coefficients of several Al–Cu–PbO alloys for radiation detection applications. The transmission geometry technique was used to calculate experimental mass attenuation coefficients at photon energies ranging from 0.662 to 1.33 MeV. To corroborate the experimental results, the mass attenuation coefficients for the alloys under consideration were calculated and confirmed by simulation using the MCNP5 method. The study analyzes the possibility of these alloys as alternative materials for nuclear radiation shielding applications.

Radiological Assessment of Background Radiation and it’s Associated Risk in Junior Secondary School Idu-Koro Abuja, Nigeria

The primary cause of natural background radiation exposure in the general public has been radon and its shortlived decay products in homes, which account for around 50% of the population's effective dose worldwide. Radon (222Rn) and its progeny inside building and environments have been recognized as a global issue and a substantial risk factor for lung cancer. In this research,Inspector alert nuclear radiation meter (manufactured by S.E international U.S.A SN:35440) with inbuilt Geiger-Muller tube was employed to determine the concentration of 222Rn in the eleven (11) investigated points at Junior Secondary School Idu-Koro Abuja, to calculate the tenants' effective dose from 222Rn and its progeny. The meter was held at the abdominal level (about 1 m above the ground surface). The dosimetric measurements were taken in count per minute (cpm) mode and the radon concentration range from to . Conversion was made from count rate to dose rate, absorb dose rate, annual dose rate and finally effective dose rate for comparison. The effective dose to the occupants was estimated ranging from to , with a mean of . The radon contents were establish to be lesser than the reference value from the international commission for radiological protection (ICRP) as the appropriate safety; hence it may not result to any health effect of lung cancer to the occupants and the members of public within the investigated areas.

General solution of Bateman equations using Cauchy products and the Theory of Divided Differences

The general solution of Bateman Equations is simplified and algorithmically improved in the present work. Such solution allows modeling successive transformations of nuclides due to radioactive decay and transmutation, considering the most general case where there are repeated nuclides or identical effective decay constants. It has been previously expressed in terms of nested sums and involving the Kronecker delta, which is a highly disadvantageous way in computational terms. An alternative procedure to overcome such disadvantages is developed in the present paper using Cauchy products and the theory of Divided Differences. Unlike the other approaches, this new procedure does not require specifying the position where repeated nuclides or repeated effective decay constants appear, simplifying considerably its computational implementation. Python codes and a set of numerical experiments are provided, where the new approach is compared with the original solution, showing that the proposed computational implementation is faster and simplified in a considerable way.

Renormalization of beta decay at three loops and beyond

The anomalous dimension for heavy-heavy-light effective theory operators describing nuclear beta decay is computed through three-loop order in the static limit. The result at order Z2α3 corrects a previous result in the literature. An all-orders symmetry is shown to relate the anomalous dimensions at leading and subleading powers of Z at a given order of α. The first unknown coefficient for the anomalous dimension now appears at O(Z2α4). Published by the American Physical Society 2024

Occupational health risk recognition, evaluation, and management of radiation workers in Gansu province, China

ObjectiveIn order to protect the health of radiation workers, scientific management of radiation workplace protection is implemented, and occupational health risks of radiation workplaces in Gansu Province, China are identified and evaluated through monitoring. MethodsThe basic situation of occupational health management of radiological workers in 1366 radiological diagnosis and treatment institutions was investigated, and 596 monitoring hospitals were selected for occupational health monitoring. Using a 2-IN∗2-in NaI (Tl) scintillation spectrometer and its supporting software, internal thyroid irradiation monitoring was performed. Fifty-one underground workers in a deep mine iron mine were selected to monitor the effect of high radon exposure. Results11 (6%) monitored hospital interventional radiology staff detected lead outside the aprons between 5 mSv and 20 mSv during a single monitoring period; In nuclear medicine, radiation monitoring in the thyroid detected 3(15%) people with doses between 5 mSv and 20msv.The chromosome aberration rate and Detection rate of posterior pole subcapsular opacification of interventional radiation group and nuclear medicine group was higher than that of conventional radiation group, and the difference between interventional radiation group and conventional medicine group was statistically significant. Abnormal detection of tumor markers in serum after sustained radon exposure accounted for 39.2% of NSE(neuron-specific enolase), 22.5% of SCC(squamous cell carcinoma associated antigen), and 5.9% of CyFRA21-1(cytokeratin 19 fragment), respectively, chest low-dose CT showed plaque and stripe shadow in 21 cases (41.2%) and nodules in 16 cases (31.4%). ConclusionIndividual dose monitoring found that radiation workers engaged in interventional radiology were exposed to higher doses and had higher occupational risks. The results of occupational health examination show that there is a certain degree of radiation injury in interventional radiology and nuclear medicine workers. Nuclear medicine radiation monitoring results show that some workplaces have radioactive contamination. The radon exposure of deep mine miners has a higher occupational risk of lung cancer caused by high radon.The analysis of chromosome aberration is an important index of occupational health monitoring of radiation workers.

Cloud-based serverless computing enables accelerated monte carlo simulations for nuclear medicine imaging

Objective. This study investigates the potential of cloud-based serverless computing to accelerate Monte Carlo (MC) simulations for nuclear medicine imaging tasks. MC simulations can pose a high computational burden—even when executed on modern multi-core computing servers. Cloud computing allows simulation tasks to be highly parallelized and considerably accelerated. Approach. We investigate the computational performance of a cloud-based serverless MC simulation of radioactive decays for positron emission tomography imaging using Amazon Web Service (AWS) Lambda serverless computing platform for the first time in scientific literature. We provide a comparison of the computational performance of AWS to a modern on-premises multi-thread reconstruction server by measuring the execution times of the processes using between 105 and 2·1010 simulated decays. We deployed two popular MC simulation frameworks—SimSET and GATE—within the AWS computing environment. Containerized application images were used as a basis for an AWS Lambda function, and local (non-cloud) scripts were used to orchestrate the deployment of simulations. The task was broken down into smaller parallel runs, and launched on concurrently running AWS Lambda instances, and the results were postprocessed and downloaded via the Simple Storage Service. Main results. Our implementation of cloud-based MC simulations with SimSET outperforms local server-based computations by more than an order of magnitude. However, the GATE implementation creates more and larger output file sizes and reveals that the internet connection speed can become the primary bottleneck for data transfers. Simulating 109 decays using SimSET is possible within 5 min and accrues computation costs of about $10 on AWS, whereas GATE would have to run in batches for more than 100 min at considerably higher costs. Significance. Adopting cloud-based serverless computing architecture in medical imaging research facilities can considerably improve processing times and overall workflow efficiency, with future research exploring additional enhancements through optimized configurations and computational methods.

Efficacy of barium and calcium additives in lithium silicate glasses for nuclear shielding applications

This study presents a detailed investigation into the nuclear radiation shielding capabilities of lithium silicate (Li2O-SiO2) glass systems, specifically examining the impact of doping with barium oxide (BaO) and calcium oxide (CaO). Utilizing advanced simulation tools, including PAGEX and SRIM for charged particle interactions, and Phy-X/PSD for gamma-ray attenuation analysis, the radiation shielding effectiveness of BaO-based and CaO-based lithium silicate glasses were systematically compared. The gamma attenuation parameters (LAC, MAC, TVL, HVL, EBF, EABF, MFP, Zeff, Neff, FNRCS, and Zeq) of investigated glass samples were computed via the Phy-X/PSD program (15 keV-15 MeV energy). The HVL values vary between 0.007–14.203 cm, and the TVL values vary between 0.054–47.182 cm for all samples in the selected energy range. The highest and lowest values of FNRCS were observed for samples BaO20 and CaO5, with the values 0.093 and 0.1 cm−1, respectively. KERMAs were calculated using PAGEX software between the 1.5 keV and 20 MeV energy range, with the highest KERMA obtained for the BaO20 sample at 0.05 MeV and the lowest KERMA obtained for the CaO5 sample at the lowest density. The mass stopping power quantities were computed between 1 keV-10 GeV energy with PAGEX. The projected range values were calculated with SRIM codes. The lowest projected range values for both alpha particles and protons were obtained for the BaO20 sample with maximum density (3.391 g cm−3). The sample with BaO20 code showed better shielding potential for alpha and proton particles with lower values of projected range and mass stopping power. Findings reveal that the Li2O-BaO-SiO2 glass composition exhibits superior gamma-ray attenuation properties compared to its CaO-doped counterpart, with the BaO20 sample demonstrating particularly enhanced performance.