Search Results (42)

The drilling core sampling and chemical analysis method for the quantitative determination of solid mineral deposits has several drawbacks, including a low core drilling efficiency, a high core sampling cost, and a long chemical analysis cycle. In current uranium quantification practices, advanced techniques have been developed to preliminarily determine the formation of uranium content based on the interpretation results of natural $\gamma$-ray total logging. However, such methods still require supplementary core chemical analysis to derive the uranium–radium–radon balance coefficient, which is then used for equilibrium correction to obtain the true uranium content within the uranium-bearing layer. Furthermore, conventional prompt neutron time spectrum logging is constrained by low count rates, resulting in slow logging speeds that fail to meet the demands of practical engineering applications. To address this, this study proposes a uranium quantification method that corrects the natural $\gamma$-ray total logging using prompt neutron time spectrum logging. Additionally, a calibration parameter determination method necessary for quantitative interpretation is constructed. Experimental results from standardized model wells indicate that, in sandstone-type uranium deposits, the absolute error of uranium content is within $\pm 0.002\%\mathrm{eU}$, and the relative error is within $\pm 2.5\%$. These findings validate the feasibility of deriving the uranium–radium–radon balance coefficient without relying on core chemical analysis. Compared with the prompt neutron time spectrum logging method, the proposed approach significantly improves the logging speed while producing results that are essentially consistent with those of natural $\gamma$-ray total logging. It provides an efficient and accurate solution for uranium quantitative interpretation. Full article

A common route for the synthesis of molybdenum nitrides is through the temperature-programmed reaction of molybdenum oxides with NH₃, or ammonolysis. In this work, the role of precursor phase, gas phase chemistry (impact of H₂O), and temperature profile on the reaction outcome (700 °C) was examined, which resulted in varying amounts of MoO₂, H₂MoO₅, and the nitride phases—cubic γ (nominally Mo₂N) and hexagonal δ (nominally MoN). The phase fraction of the δ phase increased with precursor in the sequence MoO₂ > MoO₃ > H₂MoO₅. Steam in the reaction gas also favored the production of δ over γ, but with too much steam, MoO₂ was obtained in the product. Synthesis conditions for obtaining nearly phase-pure δ were identified: MoO₂ as the precursor, 2% H₂O in the gas stream, and a moderate heating rate (3 °C/min). In situ X-ray diffraction provided insights into the reaction pathway. Extensive physico-chemical analysis of the δ phase, including synchrotron X-ray and neutron diffraction, electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and prompt gamma activation analysis, revealed its stoichiometry to be MoO_0.108(8)N_0.892(8)H_0.012(5), indicating non-trivial oxygen incorporation. The presence of N/O ordering and an impurity phase Mo₅N₆ were also revealed, detectable only by neutron diffraction. Notably, a computationally predicted MoON phase (doi: 10.1103/PhysRevLett.123.236402), of interest due to its potential to display a metal-insulator transition, did not appear under any reaction condition examined. Full article

To understand the biological effects of residual radioactivity after the atomic bomb explosion in Hiroshima and Nagasaki, we previously investigated the effects of ⁵⁶Mn, a major residual radioisotope. Our rat study demonstrated that inhalation exposure to ⁵⁶MnO₂ microparticles affected gene expression in the lungs, testes, and liver, despite the low radiation doses. Because ⁵⁶Mn is a β- and γ-emitter, the differential effects between β- and γ-rays should be clarified. In this study, ³¹Si, a β-emitter with a radioactive half-life similar to that of ⁵⁶Mn, was used to determine its effects. Male Wistar rats were exposed to sprayed neutron-activated ³¹SiO₂ microparticles, stable SiO₂ microparticles, or X-rays. The animals were examined on days 3 and 14 after irradiation. The expression of radiation-inducible marker genes, including Ccng1, Cdkn1a, and Phlda3, was measured in the spleen, lungs, and liver. Furthermore, the expressions of pathophysiological marker genes, including Aqp1, Aqp5, and Smad7 in the lungs and Cth, Ccl2, and Nfkb1 in the liver, were determined. Impacts of ³¹SiO₂ exposure were observed mainly in the liver, where the expression of Cth markedly increased on post-exposure days 3 and 14. Our data suggest that internal exposure to β-emitted microparticles has significant biological effects and its possible roles as residual radiation after atomic bombing. Full article

Radiolysis of water and aqueous solutions refers to the decomposition of water and its solutions under exposure to ionizing radiation, such as γ-rays, X-rays, accelerated particles, or fast neutrons. This exposure leads to the formation of highly reactive species, including free radicals like hydroxyl radicals (^●OH), hydrated electrons (e⁻_aq), and hydrogen atoms (H^●), as well as molecular products like molecular hydrogen (H₂) and hydrogen peroxide (H₂O₂). These species may further react with each other or with solutes in the solution. The yield and behavior of these radiolytic products depend on various factors, including pH, radiation type and energy, dose rate, and the presence of dissolved solutes such as oxygen or ferrous ions, as in the case of the ferrous sulfate (Fricke) dosimeter. Aqueous radiation chemistry has been pivotal for over a century, driving advancements in diverse fields, including nuclear science and technology—particularly in water-cooled reactors—radiobiology, bioradical chemistry, radiotherapy, food preservation, wastewater treatment, and the long-term management of nuclear waste. This field is also vital for understanding radiation effects in space. Full article

The advent of third-generation (3G) gravitational-wave (GW) detectors opens new opportunities for multi-messenger observations of binary neutron star merger events, holding significant potential for probing the history of cosmic expansion. In this paper, we investigate the holographic dark energy (HDE) model by using the future GW standard siren data observed from the 3G GW detectors and the short $\gamma$-ray burst THESEUS-like detector joint observations. We find that GW data alone can achieve a relatively precise estimation of the Hubble constant, with precision of $0.2$–$0.6\%$, but its ability to constrain other cosmological parameters remains limited. Nonetheless, since the GW data can break parameter degeneracies generated by the mainstream EM observations, CMB + BAO + SN (CBS), GW standard sirens play a crucial role in enhancing the accuracy of parameter estimation. With the addition of GW data to CBS, the constraints on cosmological parameters $H_0$, c and ${\Omega }_{\mathrm{m}}$ can be improved by 63–$88\%$, 27–$44\%$ and 55–$70\%$. In summary, observations of GW standard sirens from 3G GW detectors could be pivotal in probing the fundamental nature of dark energy. Full article

Global disparities in cancer prevention, detection, and treatment demand a unified international effort to reduce the disease’s burden and improve outcomes. Despite advances in chemotherapy and radiotherapy, many tumors remain resistant to these treatments. Gold nanoparticles (AuNPs) have shown promise as radiosensitizers, enhancing the effectiveness of low-energy X-rays by emitting Auger electrons that cause localized cellular damage. In this study, spherical AuNPs of 5 nm and 10 nm were characterized and tested on various cell lines, including malignant breast cells (MCF-7), non-malignant cells (CHO-K1 and MCF-10A), and human lymphocytes. Cells were treated with AuNPs and irradiated with attenuated 6 megavoltage (MV) X-rays or p(66)/Be neutron radiation to assess DNA double-strand break (DSB) damage, cell viability, and cell cycle progression. The combination of AuNPs and neutron radiation induced higher levels of γ-H2AX foci and micronucleus formation compared to treatments with AuNPs or X-ray radiation alone. AuNPs alone reduced cellular kinetics and increased the accumulation of cells in the G2/M phase, suggesting a block of cell cycle progression. For cell proliferation, significant effects were only observed at the concentration of 50 μg/mL of AuNPs, while lower concentrations had no inhibitory effect. Further research is needed to quantify internalized AuNPs and correlate their concentration with the observed cellular effects to unravel the biological mechanisms of their radioenhancement. Full article

A comparative study on the synergistic effect of the total ionizing dose and neutron single event effect on a SiC MOSFET and Si MOSFET was performed based on the ⁶⁰Co γ source and the high-pressure multiplier 14 MeV neutron source at the China Institute of Atomic Energy. First, a γ-ray total ionizing dose experiment was performed on these two devices, and the differences in the total ionizing dose damage of the SiC and Si MOSFETs were analyzed. Then, neutron single event effect experiments were performed to investigate the effects of different doses on the single event effect for the devices. The results indicate that the unhardened SiC MOSFET has stronger resistance to the total ionizing dose compared with hardened Si MOSFET. During the 14 MeV neutron irradiation experiment, no single event burnout was observed in either device, but single event transients were observed. Even though the hardened Si MOSFETs are capable of suppressing single event transient currents at a higher drain bias, the trapped charge concentration of SiC MOSFETs due to irradiation is smaller than that of Si MOSFETs, which improves their resistance to the total ionizing dose and makes them less affected by the synergistic effect of the total ionizing dose and neutron single event effects. The research results can provide some guidelines for the radiation hardening technology of power devices used in aerospace and nuclear industries. Full article

Reactor-emitted electron antineutrinos can be detected via the inverse beta decay reaction, which produces a characteristic signal: a two-fold coincidence between a prompt positron event and a delayed neutron capture event within a specific time frame. While liquid scintillators are widely used for detecting neutrinos reacting with matter, detection is difficult because of the low interaction of neutrinos. In particular, it is important to distinguish between neutron (n) and gamma (γ) signals. The principle of the interaction of neutrons with matter differs from that of gamma rays with matter, and hence the detection signal’s waveform is different. Conventionally, pulse shape discrimination (PSD) is used for n/γ separation. This study developed a machine learning method to see if it is more efficient than the traditional PSD method. The possibility of n/γ discrimination in the region beyond the linear response limits was also examined, by using 10- and 2-inch photomultiplier tubes (PMTs) simultaneously. To the best of our knowledge, no study has attempted PSD in a PMT nonlinear region using artificial neural networks. Our results indicate that the proposed method has the potential to distinguish between n and γ signals in a nonlinear region. Full article

Radiation detection uses semiconductor materials to convert high-energy photons into charge (direct detection) or low-energy photons (indirect detection), and it has a wide range of applications in nuclear physics, medical imaging, astronomical detection, homeland security, and other fields. Metal halide perovskites have the advantages of high frequency number, high carrier mobility, high defect tolerance, low defect density, adjustable band gap, and fast light response, and they have wide application prospects in the field of radiation detection. However, the research is still in its infancy stage, and it is far from meeting the requirements of industrial application. This paper focuses on the advantages of metal halide perovskite single-crystal materials in both semiconductors-based direct conversion detection and scintillator-based indirect detection as well as the latest progress in this promising field. This paper not only introduces the latest application of lead halide perovskite monocrystalline materials in high-energy electromagnetic radiation detection (X-ray and γ-rays), but it also introduces the latest development of α-particle/β-particle/neutron detection. Finally, this paper points out the challenges and future prospects of metal halide perovskite single-crystal materials in radiation detection. Full article

(1) Background: Supercritical water-cooled reactors (SCWRs) and their smaller modular variants (SMRs) are part of the ‘Generation IV International Forum’ (GIF) on advanced nuclear energy systems. These reactors operate beyond the critical point of water (t_c = 373.95 °C and P_c = 22.06 MPa), which introduces specific technical challenges that need to be addressed. The primary concerns involve the effects of intense radiation fields—including fast neutrons, recoil protons/oxygen ions, and γ rays—on the chemistry of the coolant fluid and the integrity of construction materials. (2) Methods: This study employs Monte Carlo simulations of radiation track chemistry to investigate the yields of radiolytic species in SCWRs/SMRs exposed to 2 MeV neutrons. In our calculations, only the contributions from the first three recoil protons with initial energies of 1.264, 0.465, and 0.171 MeV were considered. Our analysis was conducted at both subcritical (300 and 350 °C) and supercritical temperatures (400–600 °C), maintaining a constant pressure of 25 MPa. (3) Results: Our simulations provide insights into the radiolytic formation of chemical species such as e⁻_aq, H^●, H₂, ^●OH, and H₂O₂ from ~1 ps to 1 ms. Compared to data from radiation with low linear energy transfer (LET), the G(e⁻_aq) and G(^●OH) values obtained for fast neutrons show a similar temporal dependence but with smaller amplitude—a result demonstrating the high LET nature of fast neutrons. A notable outcome of our simulations is the marked increase in G(^●OH) and G(H₂), coupled with a corresponding reduction in G(H^●), observed during the homogeneous chemical stage of radiolysis. This evolution is attributed to the oxidation of water by the H^● atom according to the reaction H^● + H₂O → ^●OH + H₂. This reaction acts as a significant source of H₂, potentially reducing the need to add extra hydrogen to the reactor’s coolant water to suppress the net radiolytic production of oxidizing species. Unlike in subcritical water, our simulations also indicate that G(H₂O₂) remains very low in low-density SCW throughout the interval from ~1 ps to 1 ms, suggesting that H₂O₂ is less likely to contribute to oxidative stress under these conditions. (4) Conclusions: The results of this study could significantly impact water-chemistry management in the proposed SCWRs and SCW-SMRs, which is crucial for assessing and mitigating the corrosion risks to reactor materials, especially for long-term operation. Full article

The method of the two neutron monitors was used to analyze the parameters of the rigidity spectrum variations (RSV) of galactic cosmic ray intensity (GCR) flux in solar cycle 24 based on the data from the global network of neutron monitors. This method is an alternative to the least squares method when there are few monitors working stably in a given period, and their use in the least squares method is impossible. Analyses of the changes in exponent γ in the RSV of GCR flux from 2009 to 2019 were studied. The soft RSV (γ = 1.2–1.3) of the GCR flux around the maximum epoch and the hard RSV (γ = 0.6–0.9) around the minimum epoch of solar activity (SA) is the general feature of GCR modulation in the GeV energy scale (5, 50), to which neutron monitors were found to correspond. Therefore, various values of the RSV γ in the considered period show that during the decrease and increase period of SA, the essential changes in the large-scale structure of the heliospheric magnetic field (HMF) fluctuations/turbulence take place. The exponent γ of the RSV of the GCR flux can be considered a significant parameter to investigate the long-period changes in the GCR flux. Full article

In order to adapt to the rapid development of high-speed imaging technology in recent years, it is very important to develop scintillators with an ultrafast time response. Because of its radiation-induced ultrafast decay time, ZnO has become an important material for radiation detection and dosimetry. According to different detection sources and application scenarios, ZnO is used in various radiation detectors in different structures, including nanoarrays and nanocomposites. In this paper, the synthesis methods and research status of various nanostructured ZnO-based materials and their applications in the detection of high-energy rays (X-rays, γ-rays) and high-energy particles (α, β and neutron) are reviewed. The performance discussion mainly includes spatial resolution, decay time and detection efficiency. Full article

The synergistic effects on the 0.18 µm PPD CISs induced by neutron displacement damage and gamma ionization damage are investigated. The typical characterizations of the CISs induced by the neutron displacement damage and gamma ionization damage are presented separately. The CISs are irradiated by reactor neutron beams up to 1 × 10¹¹ n/cm² (1 MeV neutron equivalent fluence) and ⁶⁰Co γ-rays up to the total ionizing dose level of 200 krad(Si) with different sequential order. The experimental results show that the mean dark signal increase in the CISs induced by reactor neutron radiation has not been influenced by previous ⁶⁰Co γ-ray radiation. However, the mean dark signal increase in the CISs induced by ⁶⁰Co γ-ray radiation has been remarkably influenced by previous reactor neutron radiation. The synergistic effects on the PPD CISs are discussed by combining the experimental results and the TCAD simulation results of radiation damage. Full article

The effects of residual radiation from atomic bombs have been considered to be minimal because of its low levels of external radioactivity. However, studies involving atomic bomb survivors exposed to only residual radiation in Hiroshima and Nagasaki have indicated possible adverse health effects. Thus, we investigated the biological effects of radioactive dust of manganese dioxide 56 (⁵⁶MnO₂), a major radioisotope formed in soil by neutron beams from a bomb. Previously, we investigated C57BL mice exposed to ⁵⁶MnO₂ and found pulmonary gene expression changes despite low radiation doses. In this study, we examined the effects in a radiation-sensitive strain of mice, BALB/c, and compared them with those in C57BL mice. The animals were exposed to ⁵⁶MnO₂ particles at two radioactivity levels and examined 3 and 65 days after exposure. The mRNA expression of pulmonary pathophysiology markers, including Aqp1, Aqp5, and Smad7, and radiation-sensitive genes, including Bax, Phlda3, and Faim3, was determined in the lungs. The radiation doses absorbed in the lungs ranged from 110 to 380 mGy; no significant difference was observed between the two strains. No exposure-related pathological changes were observed in the lungs of any group. However, the mRNA expression of Aqp1 was significantly elevated in C57BL mice but not in BALB/c mice 65 days after exposure, whereas no changes were observed in external γ-rays (2 Gy) in either strain. In contrast, Faim3, a radiation-dependently downregulated gene, was reduced by ⁵⁶MnO₂ exposure in BALB/c mice but not in C57BL mice. These data demonstrate that inhalation exposure to ⁵⁶MnO₂ affected the expression of pulmonary genes at doses <380 mGy, which is comparable to 2 Gy of external γ-irradiation, whereas the responses differed between the two mouse strains. Full article

Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, and planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe and influence the conditions for the emergence and continuation of life. In our solar system, the Sun is the most energetic particle accelerator, and its proximity makes it a unique laboratory in which to explore astrophysical particle acceleration. However, despite its importance, the physics underlying solar particle acceleration remain poorly understood. The SPARK mission will reveal new discoveries about particle acceleration through a uniquely powerful and complete combination of γ-ray, X-ray, and EUV imaging and spectroscopy at high spectral, spatial, and temporal resolutions. SPARK’s instruments will provide a step change in observational capability, enabling fundamental breakthroughs in our understanding of solar particle acceleration and the phenomena associated with it, such as the evolution of solar eruptive events. By providing essential diagnostics of the processes that drive the onset and evolution of solar flares and coronal mass ejections, SPARK will elucidate the underlying physics of space weather events that can damage satellites and power grids, disrupt telecommunications and GPS navigation, and endanger astronauts in space. The prediction of such events and the mitigation of their potential impacts are crucial in protecting our terrestrial and space-based infrastructure. Full article