Xenon Isotopes Research Articles

Establishing the case for a May 2010 low-yield, unannounced nuclear test in North Korea

AbstractNew data, analyses and modelling are presented concerning the unprecedented mid-May 2010 series of fission product detections in ground level air on and around the Korean Peninsula. For the first time Ba-140 is revealed at Ussuriysk, for which only La-140 had been reported. Thus aerosol particles containing the same parent-daughter pair Ba-140/La-140 were detected at both Ussuriysk and Okinawa, establishing beyond reasonable doubt that their physical, spatial and temporal origins are the same. Together with Ce-141 and Cs-137, all with short-lived xenon isotope parents, a supercritical fission excursion, which experienced a near prompt filtered vent, is the only viable scenario for their explanation. New modelling suggests that the vent occurred around 9 s after the excursion and that the CTBT-relevant xenon isotopes Xe-133 and Xe-135 were ‘quenched’ around 25 min later and released some 10–20 h afterwards. Published corroborating seismic and infrasound data of an event at the North Korean nuclear test site 8 min and 45 s past midnight on 12 May 2010 is subsequently reviewed. These papers adopted a conventional depth of the event although the data suggested a shallower one. Despite arguments in the seismic community about its exact nature, it is prudent to test how well the waveform signals marry the radionuclide detection pattern. Thus the location and time are input into a new atmospheric transport model. The advanced software suite MATCH was used in forward mode with prompt and delayed releases, revealing the presence of plumes at each detection site at the time of their first detection and extending over the observed timeframe. Thus a very consistent picture of a shallow low yield nuclear test is obtained.

Data reduction strategy in the PandaX-4T experiment

The PandaX-4T experiment is designed for multiple purposes, including searches for solar neutrinos, weakly interacting massive particles, and rare double beta decays of xenon isotopes. The experiment produces a huge amount of raw data that needs to be stored for related physical analyses in a wide energy range. With the upgrading of the PandaX-4T experiment, the doubled sampling rate resulted in a larger data size, which challenges both the cost and the data processing speed. To address this issue, we propose a data reduction strategy by removing the noise tail of large signals and downsampling the remaining parts of them. This strategy reduces the requirement for storage by 65% while increasing data processing speed. The influences on physical analyses on different topics at different energy regions are negligible.

Cosmogenic background simulations for neutrinoless double beta decay with the DARWIN observatory at various underground sites

Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With 40t\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$40\\,\ extrm{t}$$\\end{document} of liquid xenon (LXe) in the TPC baseline design, DARWIN will have a high sensitivity for the detection of particle dark matter, neutrinoless double beta decay (0νββ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0\\upnu \\upbeta \\upbeta $$\\end{document}), and axion-like particles (ALPs). Although cosmic muons are a source of background that cannot be entirely eliminated, they may be greatly diminished by placing the detector deep underground. In this study, we used Monte Carlo simulations to model the cosmogenic background expected for the DARWIN observatory at four underground laboratories: Laboratori Nazionali del Gran Sasso (LNGS), Sanford Underground Research Facility (SURF), Laboratoire Souterrain de Modane (LSM) and SNOLAB. We present here the results of simulations performed to determine the production rate of 137\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${}^{137}$$\\end{document}Xe, the most crucial isotope in the search for 0νββ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0\\upnu \\upbeta \\upbeta $$\\end{document} of 136\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${}^{136}$$\\end{document}Xe. Additionally, we explore the contribution that other muon-induced spallation products, such as other unstable xenon isotopes and tritium, may have on the cosmogenic background.

Octupole correlations in the N = Z + 2 = 56 110Xe nucleus

This letter reports on the first observation of an octupole band in the neutron-deficient (N=Z+2) nucleus 110Xe. The 110Xe nuclei were produced via the 54Fe(58Ni,2n) fusion-evaporation reaction. The emitted γ rays were detected using the jurogam 3γ-ray spectrometer, while the fusion-evaporation residues were separated with the MARA separator at the Accelerator Laboratory of the University of Jyväskylä, Finland. The experimental observation of the low-lying 3− and 5− states and inter-band E1 transitions between the ground-state band and the octupole band proves the importance of octupole correlations in this region. These new experimental data combined with theoretical calculations using the symmetry-conserving configuration-mixing method, based on a Gogny energy density functional, have been interpreted as an evidence of enhanced octupole correlations in neutron-deficient xenon isotopes.

Classification of nuclear activity types for neighboring countries of South Korea using machine learning techniques with xenon isotopic activity ratios

The discrimination of the source for xenon gases' release can provide an important clue for detecting the nuclear activities in the neighboring countries. In this paper, three machine learning techniques, which are logistic regression, support vector machine (SVM), and k-nearest neighbors (KNN), were applied to develop the predictive models for discriminating the source for xenon gases’ release based on the xenon isotopic activity ratio data which were generated using the depletion codes, i.e., ORIGEN in SCALE 6.2 and Serpent, for the probable sources. The considered sources for the neighboring countries of South Korea include PWRs, CANDUs, IRT-2000, Yongbyun 5 MWe reactor, and nuclear tests with plutonium and uranium. The results of the analysis showed that the overall prediction accuracies of models with SVM and KNN using six inputs, all exceeded 90%. Particularly, the models based on SVM and KNN that used six or three xenon isotope activity ratios with three classification categories, namely reactor, plutonium bomb, and uranium bomb, had accuracy levels greater than 88%. The prediction performances demonstrate the applicability of machine learning algorithms to predict nuclear threat using ratios of xenon isotopic activity.

An extensive characterization of xenon isotopic activity ratios from nuclear explosion and nuclear reactors in neighboring countries of South Korea

This paper gives an extensive analysis on the characterization of xenon isotopic ratios for various nuclear reactors and nuclear explosions through neutronic depletion codes. The results of the characterization can be used for discriminating the sources of the xenon isotopes’ release among the nuclear explosions and nuclear reactors. The considered sources of the xenon radionuclides do not only include PWR, CANDU, and nuclear explosions using uranium and plutonium bombs, but also IRT-200 and 5MWe Yongbyon (MAGNOX reactor) research reactors operated in North Korea. A new data base (DB) on xenon isotopic activity ratios was produced using the results of the characterization, which can be used in discrimination of the sources of xenon isotopes. The results of the study show that 5MWe Yongbyon reactor has quite different characteristics in 135Xe/133Xe ratio from the PWRs and the nuclear reactors have different characteristics in 135Xe/133Xe ratios from the nuclear explosions.

A race against the clock: Constraining the timing of cometary bombardment relative to Earth’s growth

Comets are considered a potential source of inner solar system volatiles, but the timing of this delivery relative to that of Earth’s accretion is still poorly understood. Measurements of xenon isotopes in comet 67P/Churyumov-Gerasimenko revealed that comets partly contributed to the Earth’s atmosphere. However, there is no conclusive evidence of a significant cometary component in the Earth’s mantle. These geochemical constraints would favor a contribution of comets mainly occurring after the last stages of Earth’s formation. Here, we evaluate whether dynamical simulations satisfy these constraints in the context of an Early Instability model. We perform N-body simulations of the solar system’s dynamic evolution considering an outer disk of 10000 comets, different initial conditions for the inner solar system and assuming that the giant planet instability happened within ≃10 million years of the start of planet formation. Out of 30 simulations, 13 meet a list of criteria for success. We calculate the probability of collision between comets and Earth analogs component embryos through time and estimate the total cometary mass accreted in Earth analogs as a function of time. We determine that the cumulative cometary mass accreted by the Earth analogs during the first 100 million years ranges between 4 ×1021 and 5 ×1024 g. While our results are in excellent agreement with geochemical constraints, we also demonstrate that the contribution of comets on Earth might have been delayed with respect to the timing of the instability, due to a stochastic component of the bombardment. More importantly, we show that it is possible that enough cometary mass has been brought to Earth after it had finished forming so that the xenon constraint is not necessarily in conflict with an Early Instability scenario. Indeed, 2 of the 13 successful simulations provide enough comet delivery after a last giant impact happening later than 30 Myr. However, it appears very likely that a few comets were delivered to Earth early in its accretion history, thus contributing to the mantle’s budget. Finally, we compare the delivery of cometary material on Earth to Venus and Mars. These results emphasize the stochastic nature of the cometary bombardment in the inner solar system.

Nuclear Shape Transition, Triaxiality and Energy Staggering of $$\Upsilon$$-Band States for Even–Even Xenon Isotopic Chain

Nuclear Shape Transition, Triaxiality and Energy Staggering of $$\Upsilon$$-Band States for Even–Even Xenon Isotopic Chain

Measurement of the [formula omitted] and [formula omitted] reaction cross-sections and isomeric ratios induced by the 14.8 MeV neutrons

The precise measurement of the (n, 2n) reaction cross-sections of xenon isotopes is of great significance for the diagnosis of the Inertial Confinement Fusion fuel area density ρR. The preparation of xenon samples and how they can be efficiently adsorbed to obtain an optimal reaction cross section are extremely difficult in existing experiments. This work aims to use the 93Nb(n,2n)92mNb reaction cross section as the standard to calculate the cross-sections and isomeric ratio for 134Xe(n,2n)133m,gXe and 136Xe(n,2n)135m,gXe reactions. This work also aims to explore the feasibility of adsorbent selection, the method of adsorption sample and the feasibility of the method used in the laboratory. In this paper, the Geant4 program was used to simulate and calculate the adsorption factors of activated carbon and polymer for standard 152Eu multi-line sources, so as to determine the most suitable adsorption material. Next, the GammaVision analysis software was used to observe whether the characteristic γ-rays released by other isotope reaction products of xenon in the sample and packaging material had an effect on the characteristic γ-rays of the target product. Then, the basic principle of activation method and the relative measurement principle are used to calculate the cross-sections and isomeric ratio for 134Xe(n,2n)133Xe and 136Xe(n,2n)135Xe reactions. Finally, the experimental results are compared and analyzed with the existing data in EXFOR database to verify whether the experimental method is correct.

Accurate prediction of gaseous isotopes Xe and Kr concentrations from the burnup of nuclear fuel using simple regression algorithm.

Mathematical techniques for modeling and simulating dangerous or complex systems, such as nuclear technology systems, often require high-performance computing to process and analyze available data. In this paper, simple and quick method to support studies and research related to nuclear fuel is presented. This reasonably simple method helps to predict different concentrations of actinides and fission products in nuclear fuels without the need for expensive specialized programs and highly-trained researchers. The great importance of this approach is the speed of predicting the components of nuclear fuel concentrations, which in turn leads to quick decision-making, such as the possibility of operating fuel at higher burnup values, predicting the amount of gases resulting from nuclear fission (which may accumulate and cause problems in nuclear fuel such as volume swells), and other important decisions in nuclear fuel technology. The predicted equations have been generalized for higher values of burnup and compared with comparable results from MCNP codes. The equations deduced in calculating the different concentrations of xenon and krypton isotopes resulting from fission in burnup of nuclear fuel showed very precise results with discrepancies (magnitude of an error between the data points and the corresponding predicted ones) less than 2%. The suggested method offers a great advantage for researchers, which are the use one of any simple or common computational programs available to most researchers and do not need much experience to deal with, such as MATLAB, Excel that are easy to use for regression analyses. In this paper, the advantages of the proposed method are explained along with the limitations of its use.

I/Pu reveals Earth mainly accreted from volatile-poor differentiated planetesimals.

The observation that mid-ocean ridge basalts had ~3× higher iodine/plutonium ratios (inferred from xenon isotopes) compared to ocean island basalts holds critical insights into Earth's accretion. Understanding whether this difference stems from core formation alone or heterogeneous accretion is, however, hindered by the unknown geochemical behavior of plutonium during core formation. Here, we use first-principles molecular dynamics to quantify the metal-silicate partition coefficients of iodine and plutonium during core formation and find that both iodine and plutonium partly partition into metal liquid. Using multistage core formation modeling, we show that core formation alone is unlikely to explain the iodine/plutonium difference between mantle reservoirs. Instead, our results reveal a heterogeneous accretion history, whereby predominant accretion of volatile-poor differentiated planetesimals was followed by a secondary phase of accretion of volatile-rich undifferentiated meteorites. This implies that Earth inherited part of its volatiles, including its water, from late accretion of chondrites, with a notable carbonaceous chondrite contribution.

Helium isotope evidence for cryptic magmatism along Central France

Determining the source(s) of helium in regions of the crust where 3He anomalies occur can be challenging when no surface manifestations of magmatic activity or a clear active extension regime are present. This is the case of the Paris basin (France), where geothermal fluids and oils 3He/4He have been previously shown to range from 0.02 Ra up to 0.14 Ra (Marty et al., 1993; Pinti and Marty, 1995, 1998), whereas natural gases to the south of the Paris Basin (near the Massif central) show unambiguous evidence for mantle helium contribution, with 3He/4He up to 6.4 Ra (Bräuer et al., 2017). However, higher 3He/4He than the crustal endmember (∼ 0.01 Ra), as observed in the Paris Basin, could be a sign of either (i) a weak contribution of mantle He (enriched in primordial 3He) or (ii) the contribution of 3He naturally produced by nuclear reactions of lithium, for which commercially exploitable concentrations have been reported in rare-metal-rich granites. One way to distinguish between these two possibilities is to combine He isotope systematics with other noble gas tracers of mantle inputs, such as xenon isotopes. Here, we report the isotope compositions of helium and xenon, measured by static and dynamic mass spectrometry, respectively, in gas samples collected in the Nièvre County, between the Massif Central and the Paris Basin. 3He/4He ratios range between 0.16 and 0.22 Ra. Combined with previous studies, our data are consistent with a southward increase of He isotope ratios along major fault systems from the Paris Basin (∼ 0.02 Ra) towards the Massif Central (6.4 Ra). This geographical trend, paired with high precision Xe isotopes exhibiting an excess of mantle 129Xe, shows a clear mantle input that is most likely restricted to the major fault systems in Central France. The occurrence of mantle-derived helium and xenon in Central France highlights the presence of cryptic magmatism in areas with no apparent volcanic manifestations.

Simulation of radioactive fission gas release from defective PWR fuel rod using the MFPR/R mechanistic code

A software package was elaborated by coupling the mechanistic code MFPR/R with a recently developed advanced model of mass exchange in defective fuel rods, to simulate the release of radioactive gaseous fission products into the coolant during operation of a thermal reactor. To simulate the oxidation of UO2 fuel, the processes of steam dissociation and radiolysis in the rod free volume were additionally considered. The package was validated by calculating the release of krypton, iodine and xenon isotopes into the coolant from defective rods under irradiation in the pressurized light water loop of the NRX reactor at Chalk River Nuclear Laboratories. It is shown that a reasonable overall agreement between calculations and experiment for noble gas isotopes can be obtained by introducing a single fitting parameter that takes into account uncertainties in the rod geometry and the rate of hydrogen production in the rod free volume.

Efficient radioactive gas detection by scintillating porous metal–organic frameworks

Natural and anthropogenic gas radionuclides such as radon, xenon, hydrogen and krypton isotopes must be monitored to be managed as pathogenic agents, radioactive diagnostic agents or nuclear activity indicators. State-of-the-art detectors based on liquid scintillators suffer from laborious preparation and limited solubility for gases, which affect the accuracy of the measurements. The actual challenge is to find solid scintillating materials simultaneously capable of concentrating radioactive gases and efficiently producing visible light revealed with high sensitivity. The high porosity, combined with the use of scintillating building blocks in metal–organic frameworks (MOFs), offers the possibility to satisfy these requisites. We demonstrate the capability of a hafnium-based MOF incorporating dicarboxy-9,10-diphenylanthracene as a scintillating conjugated ligand to detect gas radionuclides. Metal–organic frameworks show fast scintillation, a fluorescence yield of ∼40%, and accessible porosity suitable for hosting noble gas atoms and ions. Adsorption and detection of 85Kr, 222Rn and 3H radionuclides are explored through a newly developed device that is based on a time coincidence technique. Metal–organic framework crystalline powder demonstrated an improved sensitivity, showing a linear response down to a radioactivity value below 1 kBq m−3 for 85Kr, which outperforms commercial devices. These results support the possible use of scintillating porous MOFs to fabricate sensitive detectors of natural and anthropogenic radionuclides.

Optimizing 129Xe and 131Xe relaxation in an NMR gyroscope using buffer gas pressure and wall coating

The accuracy of inertial measurement performed by the nuclear magnetic resonance gyroscope (NMRG) with two isotopes depends on the duration of transverse relaxation. Extending the relaxation of the xenon isotopes at the same time plays a very important role in the accuracy of gyro. The relaxation time of 129Xe and 131Xe can be increased to about 15–20 s by optimizing the buffer gas pressure of N2 at about 0.57 amg and coating RbH, respectively. According to the results of theoretical analysis and experimentation, the gyro stability reaches 0.6°/h, and the active measurement volume is 3 × 3 × 3 ∼ mm3.

Ultrahigh-precision noble gas isotope analyses reveal pervasive subsurface fractionation in hydrothermal systems.

Mantle-derived noble gases in volcanic gases are powerful tracers of terrestrial volatile evolution, as they contain mixtures of both primordial (from Earth's accretion) and secondary (e.g., radiogenic) isotope signals that characterize the composition of deep Earth. However, volcanic gases emitted through subaerial hydrothermal systems also contain contributions from shallow reservoirs (groundwater, crust, atmosphere). Deconvolving deep and shallow source signals is critical for robust interpretations of mantle-derived signals. Here, we use a novel dynamic mass spectrometry technique to measure argon, krypton, and xenon isotopes in volcanic gas with ultrahigh precision. Data from Iceland, Germany, United States (Yellowstone, Salton Sea), Costa Rica, and Chile show that subsurface isotope fractionation within hydrothermal systems is a globally pervasive and previously unrecognized process causing substantial nonradiogenic Ar-Kr-Xe isotope variations. Quantitatively accounting for this process is vital for accurately interpreting mantle-derived volatile (e.g., noble gas and nitrogen) signals, with profound implications for our understanding of terrestrial volatile evolution.

Energy resolution of the LZ detector for high-energy electronic recoils

The LUX-ZEPLIN (LZ) detector is a dual-phase liquid xenon time projection chamber (TPC) installed at the Sanford Underground Research Facility (Lead, South Dakota) at a depth of 1478 meters. Although the main objective of LZ is the direct detection of dark matter, its low background environment allows for the search of other rare processes, such as the neutrinoless double beta decay of xenon isotopes 134Xe and 136Xe with the respective Q-values of 826 keV and 2458 keV. The sensitivity of the detector to these decays is directly determined by the energy resolution, which, in turn, is degraded by non-uniformities in detector response. In this work, we present a novel method to correct, in the data, the non-uniformity of the light collected by an array of photosensors in a scintillation detector. This method is based on the knowledge of the light response functions of individual photosensors. With these techniques, we report, at a very early phase of the detector operations, a state-of-the-art energy resolution (σ/μ) of (0.67 ± 0.01)% at 2614 keV for the fiducial volume of 5.6 tonnes of liquid xenon.

SAUNA III - The next generation noble gas system for verification of nuclear explosions

The SAUNA III represent the next generation of the SAUNA systems designed for detection of low levels of radioactive xenon in the atmosphere, with the main purpose of detecting underground nuclear explosions. The system automatically collects, processes and measures 40 m3 atmospheric samples every 6 h, increasing both the sensitivity and time resolution as compared the systems currently in use. The higher sensitive increases the number of detections, especially for samples were more than one isotope of xenon are detected. This improves the understanding of the background and the possibility to screen out signal from civilian sources. The increased time resolution of the new system also provides a more detailed picture of the plumes, especially important for near-by sources. The design of the system as well as data from the first two years of operation are presented.

Boosting Xe/Kr separation by a Mixed-linker strategy in Radiation-Resistant Aluminum-Based Metal − Organic frameworks

Capturing and separating radioactive isotopes of Xenon (Xe) and Krypton (Kr) from off-gas streams in the reprocessing of used nuclear fuel (UNF) gaseous radioactive nuclides emerges as a major concern to meet the rapid growth and sustainable development of nuclear energy. Owing to the inert atomic gases (Xe and Kr) nature without dipole or quadruple moments and their existing extremely low concentrations in radioactive off-gas mixture, it is a grand challenge to design radiation-resistant porous adsorbents for efficient Xe capture and Xe/Kr separation at dilute conditions. Herein, we report a mixed-linker strategy to realize a confined aliphatic pore environment in high radioactive stable CAU-10 type Aluminum-based MOFs using isophthalate and 5-methylisophthalate as mixed linkers for Xe/Kr separation at low concentration. By systematically tune the ratio of the two linkers, the precise and appropriate amount of aliphatic methyl groups could be immobilized on the framework to achieve delicate regulation of pore structure (pore shape and pore size), which significantly increase Xe binding affinity. Mixed-linker CAU-10-H-CH3-0.21–0.79 shows significantly enhanced Xe capture and separation performance at dilute conditions compared to pristine CAU-10-H and fully methyl functionalized CAU-10-CH3, demonstrated by adsorption isotherms and breakthrough curves. The high radioactive stability of CAU-10 type Al-MOFs was also identified by gamma-ray irradiation experiments, suggesting a great potential for practical application.

Global emission inventory of 131mXe, 133Xe, 133mXe, and 135Xe from all kinds of nuclear facilities for the reference year 2014

Global radioactivity monitoring for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes the four xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe. These four isotopes are serving as important indicators of nuclear explosions. The state-of-the-art radioxenon emission inventory uses generic release estimates for each known nuclear facility. However, the release amount can vary by several orders of magnitude from year to year. The year 2014 was selected for a single year radioxenon emission inventory with minimized uncertainty. Whenever 2014 emissions reported by the facility operator are available these are incorporated into the 2014 emission inventory. This paper summarizes this new emission inventory. The emissions are compared with previous studies. The global radioxenon emission inventory for 2014 can be used for studies to estimate the contribution of this anthropogenic source to the observed ambient concentrations at IMS noble gas sensors to support CTBT monitoring activities, including calibration and performance assessment of the verification system as described in the Treaty as well as developing and validating methods for enhanced detection capabilities of signals that may indicate a nuclear test. One specific application is the 1st Nuclear Explosion Signal Screening Open Inter-Comparison Exercise announced end of 2021.