Search Results (347)

Borehole effects are a critical source of uncertainty in uranium fission prompt neutron (PFN) logging, particularly in sandstone-type uranium deposits with complex borehole conditions. This study develops a quantitative correction method for borehole diameter effects based on Monte Carlo numerical simulations and the epithermal-to-thermal neutron ratio (E/T ratio). A 1:1 Monte Carlo model of the PFN logging system and a representative sandstone formation model were established to investigate neutron transport behavior under varying borehole diameters and tool positions (centered and eccentered). The simulation results show that both epithermal and thermal neutron count rates decrease with increasing borehole diameter, while the E/T ratio exhibits a nonlinear decreasing trend. This behavior indicates that borehole geometry significantly influences neutron moderation and detection efficiency. Based on the relationship between borehole diameter and the E/T ratio, a correction function for borehole effects was derived using curve fitting methods. The proposed model was validated against Monte Carlo simulation results and experimental measurements, showing relative errors within 10%. The results demonstrate that the proposed method can effectively quantify and correct borehole diameter effects in PFN logging. This provides a physics-based and geometry-dependent correction framework for improving the accuracy of uranium quantification in complex borehole environments. Full article

The Standard Model accurately describes particle phenomena through continuous gauge fields, color, chirality, generations, and Yukawa couplings, but it does not derive these labels from a deeper structural principle. This paper proposes a carrier-resolution interpretation in which particle species are carrier-readable manifestations of a common loop-detectable codimension-two archetype defect. The carrier supplies Lorentzian propagation and globally available $U\left(1\right)$ phase closure, while particle labels arise through holonomy, embedding, closure, and read-out conditions. The first persistent asymmetric resolution contains a lepton-like $Z_2$-Lorentz branch and a hadron-supporting branch with confined $Z_3$ closure. The $Z_2$ branch accounts for spinorial and chiral read-out through twofold holonomy and Lorentz embedding, while the three observed fermion generations are interpreted as the three leading saturated projective embedding layers of the common $Z_2$-Lorentz branch, not as consequences of the $Z_3$ color-like layer. In this framework, $Z_3$ supplies hadronic sectorality, and higher $Z_n$ refinements provide suppressed mass and response corrections rather than additional ordinary generations. The usual $SU{\left(3\right)}_C$ QCD description is retained as the effective after-read-out continuum gauge theory of color dynamics revealed by high-energy probes. The proposal does not replace QCD; instead, it interprets confined $Z_3$ closure as a pre-read-out structural condition whose incomplete sectors are not carrier-readable as isolated hadrons. As a quantitative test, the neutron–proton magnetic-moment ratio is derived from an ideal $Z_3$-complete baseline, a rule-generated closure-interface sequence, and a neutral-parent magnetic completion. The same-branch sequence reaches a sub-ppm residual and then saturates, so the remaining discrepancy is assigned to a neutral magnetic-completion seam rather than to deeper $Z_n$ terms. The resulting prediction is $-0.684979364944$, differing from the CODATA value of $-0.68497935\left(16\right)$ by about $0.022$ ppm, or $0.093$ standard deviations. No coefficient is adjusted to fit the observed value. The result is presented as a sharp no-fit test of carrier-resolution and neutral-parent closure, not as a replacement for QCD or a complete theory of all baryon magnetic moments. Full article

Be/X-ray binaries constitute the largest and most diverse subgroup of neutron star high-mass X-ray binaries. These systems feature a rapidly rotating Be star surrounded by a circumstellar decretion disk that serves as the primary reservoir of accreted matter onto a strongly magnetized neutron star. While a few Be/X-ray binaries remain persistently active, the majority manifest as hard X-ray transient sources, becoming detectable only during X-ray outbursts. This review synthesizes current understanding of their rich phenomenology across optical and X-ray wavelengths, focusing on variability ocurring over timescales that span from seconds to years. Full article

Discrete breathers (DBs) are nonlinear vibrational excitations localized on small groups of atoms in perfect crystal lattices. While theoretically proven, a systematic understanding of DB formation in binary crystals with the B2 structure remains limited. We employ molecular dynamics simulations using the LAMMPS package to investigate the nonlinear dynamics of three representative B2 crystals: ionic CsCl, and intermetallic LiPb and NiTi. We calculate the amplitude-frequency dependencies of delocalized nonlinear vibrational modes (DNVMs) and analyze DB existence conditions based on phonon spectrum features and anharmonicity type. Our analysis reveals that a significant atomic mass difference creates a phonon band gap, enabling gap DBs in CsCl and LiPb, whereas NiTi, with similar atomic masses, exhibits no gap. A simplified model assuming identical bond stiffnesses accurately predicts frequency ratios in CsCl and LiPb but fails for NiTi due to strong bond stiffness asymmetry. We demonstrate the successful excitation of long-lived gap DBs in LiPb by initializing atomic displacements based on the G1 DNVM pattern on heavy Pb atoms. These gap DBs remain stable for over 20 ps with negligible energy dissipation. In contrast, DBs with frequencies above the phonon spectrum (excited on light Li atoms) exhibit shorter lifetimes (~2 ps). The study establishes that both atomic mass ratio and interatomic bond stiffness asymmetry are critical parameters governing nonlinear dynamics in B2 crystals. The predicted long-lived gap DBs in LiPb provide a target for future experimental detection via inelastic neutron or X-ray scattering, offering new insights into energy localization and transport in biatomic alloys. Full article

Neutron noise in pressurized water reactors (PWRs) is mainly induced by fluctuations in macroscopic neutron cross-sections, which can be triggered by various factors such as vibrations of reactor internals. Existing studies mostly focus on calculation methods and software development of neutron noise, as well as in-core inversion diagnosis of noise source. Given the considerable differences in core design between Chinese PWRs CPR1000 and HPR1000, analyzing their propagation characteristics of neutron noise is significant for in-core anomaly detection and diagnosis of specific reactor types. This paper establishes a high-precision calculation method of neutron noise based on the transient neutron diffusion equation and Fourier transform technique. By simulating noise sources from macroscopic cross-section fluctuations, time-dependent relative power of each fuel assembly is obtained, and the amplitude and phase distribution of power fluctuations is derived via Fourier transform for propagation characteristic analysis. Simulations are conducted with assembly vibration noise sources for first-cycle and equilibrium-cycle cores of the HPR1000 and CPR1000. Numerical results indicate that propagation characteristics of core neutron noise are mainly dominated by noise source location and core configuration, with minor influence from burnup. Full article

This research investigates atmospheric neutron-induced single event effects (SEEs) on advanced artificial intelligence (AI) chips during natural environment operation. The RK3588 neural processing unit (NPU) is the evaluated target chip, and its SEE is assessed through a combination of irradiation testing and software fault injection. During the irradiation test, the chip was exposed to a spectrum neutron at the China Spallation Neutron Source. Upon reaching a cumulative fluence of 8.25 × 10⁹ n·cm², a total of 14,018 soft errors were detected, of which 99.97% manifested as variations in target recognition accuracy and network inference latency. Among these variations, both detrimental effects (reduced target recognition accuracy or prolonged network inference time) and beneficial effects (enhanced target recognition accuracy or shortened network inference time) caused by single event effects were observed. In addition, atmospheric neutron single event effects were found to cause NPU operation suspension and system crashes. Based on the irradiation test results, failure predictions for neural processing units in real-world environments were estimated, and mitigation recommendations were proposed. Furthermore, software fault injections were employed to conduct in-depth analysis of detected soft errors during irradiation testing. This research provides support and references for the reliable application of artificial intelligence chips in natural environments. Full article

It is well known that axions or axion-like particles can mediate spin-dependent interactions. If such interactions exist, they may violate the equivalence principle of general relativity, causing a polarized fermion with nonzero mass to experience different gravitational effects for different spin orientations. In this work, we derive the spin-dependent gravitational interaction generated by a spherically symmetric celestial body and apply the formalism to the Earth. We compare existing experimental searches for spin-dependent gravitational effects with the constraints implied by axion-mediated interactions. We further note that a rotating polarized neutron star may generate a time-dependent spin–mass interaction field acting on an unpolarized probe mass, which could be detected with high-frequency, high-Q torsion oscillators. Full article

Pixelated detectors based on inorganic scintillation materials are widely used in radiation detection systems for medical imaging and many other fields of science and technology. A substantial application is X-ray scanning using flat-panel detectors (FPDs) for both fluorography and mammography. In this article, the detection properties of the monolithic planar ceramic scintillation elements are reported for the first time. A high-light yield (Gd,Y)₃Al₂Ga₃O₁₂:Ce,Mg garnet-type scintillation material was used to form square-shaped pixels, while a material of similar composition was used as a substrate. Green bodies were successfully fabricated by a digital light processing (DLP) 3D printing method. Subsequent debinding and pressureless high-temperature sintering resulted in composite elements consisting of two layers with different chemical compositions. The lower bulk layer consisted of transparent, non-luminescent garnet, whereas the upper pixelated layer, with pixel dimensions of 230 × 230 µm, was made of scintillation material. The spatial resolution of the matrices under UV light and alpha-particle excitation was evaluated. It was confirmed that the spatial resolution of the matrices produced by the developed technology is approximately 0.4 times the pixel size. The proven ability of the integrated technology of inorganic scintillation matrix production opens the way for future improvement in spatial resolution through optimizing the printed pixel dimensions. Full article

Cosmic-Ray Neutron Sensing (CRNS) has become a standard method for non-invasive soil moisture monitoring at the field scale. With most CRNS sensors being derivatives from scientific nuclear equipment, the development of instruments based on alternative neutron detection technologies is a major development goal for CRNS. We present a modular instrument family based on boron-10-lined proportional counters, specifically designed for long-term autonomous field operation. The system is controlled by a data logger supporting various telemetry options and external SDI-12 environmental sensors, while the frontend electronics use pulse-height and pulse-length information to suppress non-neutron background and electronic noise. Our results show high energy efficiency, with the latest generation close to 50 mW, allowing solar-powered operation even in challenging environments. The performance of the instruments is validated within long-term field deployments in different settings, showing that boron-10-based systems provide a scalable, low-power and cost-efficient alternative for the next generation of CRNS monitoring networks. Full article

The reaction dynamics of weakly-bound nuclear systems at near-barrier energies is a compelling topic in nuclear physics. This review summarizes decades of experimental work by the Nuclear Reaction Group at the China Institute of Atomic Energy. Using transfer reactions with the distorted wave born approximation and asymptotic normalization coefficient analyses, we confirm the first excited neutron halo (¹³C) on the $\beta$-stability line and identified new halo states in ¹²B. Total reaction cross-section measurements revealed proton halo nuclei ${}^{27}\mathrm{P}$ and ${}^{29}\mathrm{S}$, with core enlargement observed in ${}^{27}\mathrm{P}$ and ${}^{28}\mathrm{P}$. We established conditions for halo formation and delineated the proton halo existence region. In two-proton emission studies, we observed ${}^2\mathrm{He}$ cluster emission from highly excited ${}^{17,18}\mathrm{Ne}$ and ${}^{28,29}\mathrm{S}$, with ${}^{29}\mathrm{S}$ being the second such case internationally. In $\beta$-delayed decay, we discovered $\beta$2p emission in ${}^{22}\mathrm{Si}$ and determined its mass, observing isospin-symmetry breaking in ${}^{20}\mathrm{Mg}$, ${}^{22}\mathrm{Si}$, and ${}^{27}\mathrm{S}$. Decay schemes for ${}^{27}\mathrm{S}$ and ${}^{26}\mathrm{P}$ addressed the ${}^{26}\mathrm{Al}$ abundance problem. For nuclear interactions, we investigated the ${}^6\mathrm{He}$ optical potential, finding the dispersion relation inapplicable for ${}^6\mathrm{He}$ + ${}^{209}\mathrm{Bi}$, and developed notch and Bayesian methods to constrain uncertainties. For unstable nuclei, the proton drip-line systems ⁸B and ¹⁷F have been intensively studied via complete kinematics measurements of the ⁸B + ¹²⁰Sn and ¹⁷F + ⁵⁸Ni reactions, respectively. The results show that elastic breakup dominates for proton-halo ${}^8\mathrm{B}$, while inelastic breakup prevails for ${}^{17}\mathrm{F}$, with proton-rich nuclei exhibiting lower breakup probabilities than neutron-halo nuclei due to Coulomb effects. Fusion studies revealed sub-barrier enhancement in ${}^{17}\mathrm{F}$ + ${}^{58}\mathrm{Ni}$ from continuum couplings. We propose direct fusion–evaporation measurements with deflection systems integrated with breakup detection to disentangle complete and incomplete fusion channels. Full article

Strong magnetic fields and anisotropic stresses can substantially modify the structure and observable properties of compact stars. In this review, we present a unified treatment of magnetically induced anisotropy across neutron stars, hybrid stars, and white dwarfs, connecting the microphysical equation of state effects to macroscopic structure and multimessenger observables. We demonstrate that magnetic-field geometry plays a decisive role: toroidally oriented (transverse) fields enhance the maximum mass by providing additional perpendicular pressure support, whereas radially oriented fields primarily increase central compression with comparatively small mass gain. In neutron stars, anisotropy and magnetic stresses can shift phase-transition thresholds in hybrid models and enable configurations in the lower mass gap with significantly smaller magnetic energy compared to the gravitational binding energy. We further show that continuous gravitational wave emission from magnetically deformed neutron stars provides a complementary probe of internal field geometry through ellipticity-driven strain evolution. In magnetized white dwarfs, super-Chandrasekhar masses arise from the spatial redistribution of magnetic stresses rather than from globally strong magnetic energy. Taken together, these results highlight that magnetic-field geometry and matter anisotropy are as important as field strength in determining mass–radius relations, tidal deformability, gravitational wave detectability, and the emergence of extreme compact-star configurations. Full article

Neutron capture reactions are the main contributors to the synthesis of heavy elements through the s-process. ²²Ne$(\alpha ,\mathrm{n})$²⁵Mg is the main neutron source in stars, together with ¹³C$(\alpha ,\mathrm{n})$¹⁶O. At energies ${\mathrm{E}}_{\mathrm{cm}}$ < 700 keV, limited data are available, i.e., reaction cross-section upper limits from direct experiments and highly uncertain estimates from indirect sources exist. The ERC project SHADES is currently performing direct cross-section measurements at these energies. We will present details on the ongoing experiment and discuss target characteristics, experimental backgrounds, and preliminary analyses on the detector efficiency and the 832 keV resonance. Full article

With the detection of kilonova AT2017gfo, (binary) neutron star mergers emerged as possible astrophysical sites for heavy element nucleosynthesis via r-process. To verify this claim, it is key to identify elements such as lanthanides and actinides in kilonovae spectra. Theoretical calculations arise as a solution to fill the scarcity of experimental atomic data to perform this identification. This work presents theoretical calculations with the AUTOSTRUCTURE atomic code for Ho, Er, Tm, Yb and Lu singly and doubly ionised, and benchmarks them against experimental data. The similarity between these theoretical calculations and experimental data was quantified via a mean absolute relative error (MARE), which showed that the calculations yield an average MARE of 58.7% and 56.7% for the singly and doubly ionised species, respectively. Full article

Background: Boron neutron capture therapy (BNCT) is a type of targeted radiotherapy with considerable therapeutic potential that may be combined with immune checkpoint inhibitors (ICIs) to enhance systemic antitumor immunity. Its efficacy relies on the efficient and safe delivery of boron to cancer cells. This study evaluated the acute toxicity of a self-assembling peptide-based boron carrier composed of A6K and sodium borocaptate (BSH) at a 1:10 molar ratio (A6K/BSH boron drug), which had previously shown excellent tumor-selective accumulation and prolonged intracellular retention. Methods: A single-dose intraperitoneal toxicity study was performed in 6-week-old BALB/c mice (n = 6 per group; 3 males and 3 females). Animals received BSH-equivalent doses of 0, 30, 100, 300, or 600 mg/kg and were observed for 14 days. Mortality, clinical signs, body weight, gross necropsy findings, and histopathological characteristics of major organs were then assessed. Results: No mortality or treatment-related clinical signs were observed. Body weight changes were comparable between the control and treated groups. Gross necropsy revealed no treatment-related abnormalities. Histopathology showed mild hepatocellular hypertrophy and granular degeneration without dose dependency. No other organ toxicities or sex-related differences were detected. Conclusions: A single intraperitoneal administration of the A6K/BSH boron drug up to 600 mg/kg (BSH-equivalent) produced no evident acute systemic toxicity, suggesting that the approximate lethal dose exceeds 600 mg/kg for both sexes. This initial safety assessment supports the further development of the A6K/BSH boron drug as a boron delivery agent for BNCT. Further studies are needed to confirm its safety under clinically relevant conditions. Full article

We investigate whether short-range nucleon–nucleon correlations (NN-SRC) and cluster configurations in nuclei can be explored by studying spectator neutrons produced in high-energy nucleus–nucleus collisions. In particular, we propose to measure the multiplicity distributions of forward spectator neutrons in symmetric ¹²C–¹²C and ⁴⁰Ca–⁴⁰Ca collisions at $\sqrt{s_{\mathrm{NN}}}=11$ GeV with the Spin Physics Detector (SPD) at the NICA facility. To assess this method, we simulate the production of spectator nucleons in these reactions using the Abrasion–Ablation Monte Carlo for Colliders model with MST clustering (AAMCC-MST). Short-range nucleon–nucleon correlations inside ¹²C and ⁴⁰Ca are implemented via a Monte Carlo rejection sampling procedure. Our results indicate that spectator production exhibits only a weak dependence on the specific features of NN-SRC. We also observe that including $\alpha$-cluster configurations in ¹²C leads to a reduction of the average multiplicity of spectator neutrons as a function of collision centrality. Full article