Time-of-flight thermal neutron total scattering measurements of light and heavy water were reproduced using the CSNS in-house Monte Carlo neutron-transport code Prompt, with emphasis on detector response and on the accurate derivation of thermal neutron scattering cross sections. In this work, a unified data-reduction procedure is developed to process both the measured and simulated detector events for estimating angular distributions, wavelength distributions, and angular differential cross sections. The reduction results of simulations and experiments show a high degree of consistency. The prominent inelasticity signatures observed in the experiments can be accurately reproduced in simulations. The origin of the inelasticity effects is analyzed, and their suppression is demonstrated when inelastic scattering is explicitly considered in the simulations. In addition, multiple scattering in the samples is quantified and discussed.
The characteristic structure of cosmic-ray anisotropy around 200 GeV provides a key opportunity to study the origin and propagation of cosmic rays. With an anisotropy amplitude of only 10^-4 at this energy, this regime is particularly well suited for testing anisotropy models. Existing space- and ground-based experiments have not yet achieved sufficiently accurate measurements of this structure. The High Altitude Detection of Astronomical Radiation (HADAR) experiment may be particularly well suited to address this issue. This paper presents the expected HADAR observations of large-scale cosmic-ray anisotropy in the 0.1–10 TeV range. The analysis indicates that HADAR should achieve the statistical precision required to resolve anisotropy amplitudes of approximately 0.01
A new adiabatic radio-frequency (RF)-flipper prototype was recently developed at the China Spallation Neutron Source. The prototype device was calibrated at the test beamline BL-20 over a wavelength range from 1.0 to 5.5 Å, and it achieved a flipping efficiency of 97
Three-dimensional (3D) integration using through-silicon vias (TSVs) has emerged as a key technology for extending Moore’s law as transistor scaling approaches its physical limits. However, ensuring the electrical reliability of TSVs in radiation environments remains challenging. This study investigates the impact of the total ionizing dose (TID) irradiation on the transmission performance and parasitic effects of the TSV channel. Three types of test samples of varying sizes and TSV arrangements were fabricated and exposed to ^60Co γ -ray irradiation. The S-parameters were measured at different doses. The experimental results indicate that increasing the irradiation dose leads to greater insertion loss, narrower −1 dB bandwidth, higher rate of change in group delay, longer propagation delay, and a reduced peak-to-peak group delay. At 180 krad(Si), the maximum propagation delay increased by 1.58 S_21 magnitude, shifting the dominant effects toward lower frequencies. The impact of the TID on the electrical parameters and material properties of TSVs was quantified by developing an equivalent circuit topology considering crosstalk effects. Optimization was then performed in an advanced design system using the validated equivalent circuit to extract changes in the parasitic parameters. The optimization results indicate that increasing the irradiation dose leads to higher silicon substrate, crosstalk, and oxide layer capacitances, whereas the silicon substrate and crosstalk conductance decrease. These changes are attributed to TID-induced modifications in the material properties of the TSV channel. Subsequently, polynomial fitting was employed to establish the functional relationships between the material properties and the irradiation dose. Consequently, a dose-dependent electrical model of TSVs was developed. This study provides a guiding strategy for evaluating the electrical behavior of TSVs under irradiation and contributes to the design of irradiation-tolerant 3D integrated circuits for high-reliability applications.
Traditional accelerator-based pulsed neutron sources are limited by the time duration, making high-resolution spectroscopy for fast neutrons difficult to conduct. Laser-plasma accelerator-based photonuclear neutron sources have ultrashort beam durations. However, accurate measurement of the neutron energy spectra with high resolution requires investigation. In this study, a laser-driven ultrashort neutron source was combined with single-neutron-counting time-of-flight technology to precisely measure energy spectra. This method resulted in a neutron source with a 2.18-ns duration, a neutron yield of (1.63 ± 0.39) × 10^6 per shot, and an energy resolution of 7
A low-gain avalanche diode (LGAD) is a new type of silicon detector with wide application prospects in particle physics experiments owing to its excellent timing resolution. LGAD sensors, with a pixel size of 1.3 mm × 1.3 mm, were used to construct a high-granularity timing detector (HGTD) in ATLAS experiments, to suppress the pileup caused by a large number of particles hitting the detector almost simultaneously, using timing information. Similarly, the CMS endcap timing layer (ETL) upgrade also plans to adopt LGAD sensors. However, pixel LGADs are characterized by higher readout electronics densities and costs, which limits their application. To decrease the readout electronics density, the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences has designed strip LGADs with larger areas. The strip LGADs each measure 19 mm in length, with varying widths of 1.0, 0.5, and 0.3 mm. The Circular Electron Positron Collider (CEPC) also proposes detectors using strip LGADs. This article provides a detailed introduction to the design parameters of these strip LGADs and their electrical characteristics, including leakage current, breakdown voltage, and depletion capacitance. The timing resolution and signal-to-noise ratio of three-strip LGAD sensors were investigated using a beta source test system. For the first time, a picosecond (ps) laser test system was used to test and analyze the position resolution parallel to the strip direction. The results demonstrate that the timing resolution of strip LGADs is approximately 37.5 ps, and the position resolution parallel to the strip direction is better than 1 mm.
Nuclear data are a fundamental resource underpinning nuclear science research and technological applications. Currently, nuclear data are distributed across multiple databases and encoded in heterogeneous formats, which complicates data integration and limits efficient knowledge mining and downstream applications. The construction of a nuclear data knowledge graph can effectively integrate heterogeneous data from multiple sources and provide support for applications such as question answering, retrieval, and recommendation. However, existing knowledge graph studies in nuclear science and technology remain largely limited to textual information, which can result in incomplete knowledge representation and missing semantic associations. To this end, this paper proposes a nuclear data multimodal knowledge graph (NDMKG) construction method. First, the ontology structure of NDMKG is designed and multimodal data is obtained from authoritative sources. For text data, a rule-based approach is used to extract structured knowledge; for image data, object detection, relation prediction, and optical character recognition techniques are integrated to achieve automatic extraction of entities, relationships, and attributes. Subsequently, the fusion of image and text knowledge is achieved by entity alignment, and the results are stored in a graph database to complete the construction of NDMKG. To enable fine-grained entity and relation extraction from decay scheme image data, this paper proposes a rotated object detection model, Rotated R-CNN, and an image relation prediction model, ImgRel. The experimental results show that Rotated R-CNN outperforms existing models on the constructed decay-scheme dataset, while ImgRel achieves optimal performance through multiple feature fusion. These results validate the effectiveness of the proposed models in knowledge extraction for decay schemes. Finally, a visualization system is developed based on NDMKG to support knowledge querying and filtering. This system provides an application interface for multimodal exploration of nuclear data.
A new pixelated prompt gamma imaging detector (PPGID) was developed for prompt gamma spectrum and gamma source position measurement. The PPGID prototype is composed of 30 independent pixelated scintillator detectors that can simultaneously obtain the gamma spectrum. The prototype has two LaBr_3 scintillator modules for gamma ray spectrum measurement with good performance in terms of energy resolution and one BGO module with high efficiency in high-energy detection. Therefore, in this study, a compound advanced imaging device based on energy spectrum detection was designed, assembled, and tested with radioactive sources. This device is called a pixelated prompt gamma imaging detector system (PPGID). The PPGID can correctly measure the source position as predicted by the FOV mathematical model. Both LaBr_3 and BGO can reproduce the gamma spectrum of the radioactive source. The tested energy response of LaBr_3 is 0.03–2.6 MeV, and that of BGO is 1–2.6 MeV with ^22Na and ^232Th . Dedicated data acquisition software was developed for energy calibration and gamma count histogram distribution. The gamma count histogram can be transformed into a thermal map which is the basis of the image.
In this study, a compact 16-channel integrated charge- and current-sensitive preamplifier, called CCPA, was developed for a large-scale detector array used in nuclear physics experiments. The CCPA was designed to achieve pulse-shape discrimination for silicon detectors. CCPA has a fast response of typically less than 6 ns for the pulse rise time and a low equivalent noise of 1.5 keV at zero input capacitance. The energy dynamic range and pulse decay time can be easily adjusted for different applications by changing feedback capacitance C_f and resistance R_f . A good energy resolution of 26.87 keV was achieved for 5.486 MeV α particles from ^241Am . The pulse-shape discrimination method was applied for the first time in an experiment carried out on the Radioactive Ion Beam Line in Lanzhou (RIBLL1), and CCPA demonstrated high resolution and stability in beam experiments. The experiment identified low-energy α particles as low as 5 MeV by the pulse-shape discrimination method, as well as hundreds of MeV charged particles. This provides a new routine for the high-precision measurement of low-energy charged particles emitted by light nuclear reactions.
High-precision measurements of γ -ray angular distributions and cross sections from neutron inelastic scattering are essential for both fundamental nuclear physics and nuclear technology applications. However, such measurements at white neutron sources are severely hampered by intense pulse pileup, particularly in the fast-neutron region. This work presents a comprehensive investigation of (n,n^'γ ) reactions on ^56Fe , ^48Ti , and ^52Cr at the CSNS Back-n beamline. A key innovation was the deployment of a high-performance LaBr _3 (Ce) detector array coupled with an advanced pulse pileup recovery algorithm, which successfully reconstructs individual events at extreme counting rates up to 6× 10^7 s ^-1 and resolves pulses separated by as little as 10 ns. This capability eliminated the need for traditional, model-dependent pileup-loss corrections and enabled the extraction of clean γ -ray spectra across the entire neutron energy range. We report the incident-energy-dependent Legendre coefficients ( a_2 , a_4 ) for five characteristic E2 transitions from 0.9 to 14 MeV. Furthermore, the absolute inelastic-scattering cross sections for the first excited 847-keV state in ^56Fe and the first excited 1434-keV state in ^52Cr were determined using a relative normalization method. Our results show excellent agreement with previous experimental data and provide an experimental benchmark for validating and constraining theoretical nuclear-reaction models.
The giant and pygmy dipole resonances in ^13C are studied within the extended quantum molecular dynamics (EQMD) model. Calculations for a non-clustered, spherical configuration fail to reproduce the measured spectrum. In contrast, a triangular 3α + n cluster structure successfully reproduces the main peaks of the giant dipole resonance and the low-energy peak of the pygmy dipole resonance spectrum when oscillations along different axes are treated separately.
The -delayed neutron emission probability ( P_n ) is a key observable for characterizing the decay strength of very neutron-rich nuclei and the rapid neutron capture process in nuclear astrophysics. A Long Helium-3 Neutron Array (LHENA) has been developed at the Beijing Rare Isotope Facility (BRIF) to enable P_n measurements using Isotope Separator On Line (ISOL) pulsed beams. LHENA is designed to work in conjunction with a tape driver and auxiliary detectors, so that particles, -delayed neutrons and γ rays emitted from the implanted nuclei can be measured simultaneously in cyclic mode. LHENA consists of 21 long ^3 He proportional counters embedded in a polyethylene moderator with a two-ring configuration, which provides a flat neutron detection efficiency up to 3 MeV according to our Geant4 simulations. The detection efficiency has been experimentally determined to be 16.4( ± 0.4 ) ^51 V(p,n) ^51 Cr reaction for neutron energies in the 120–700 keV range. A good efficiency flatness and a very low background have been verified for LHENA, laying a solid foundation for the first P_n measurement using very neutron-rich Rb isotopes at BRIF.
A five-channel proton detector (PD) based on Passivated Implanted Planar Silicon (PIPS) detectors has been developed and installed on the HL-3 tokamak to measure protons and tritons ( ^3H^+ ions) produced by the D–D fusion branch d(d,p)t. Featuring tungsten shielding, platinum foils, and optimized collimators for noise suppression, the system design was informed by a self-developed Monte Carlo code (CFPMC) employing a fourth-order Runge–Kutta method to simulate proton trajectories and optimize detector placement. During the 2024 experimental campaign, initial results confirmed the system’s ability to measure proton flux with temporal and pitch angle resolution during neutral beam injection (NBI) discharges. Clear modulation of proton signals by sawtooth crashes was observed, with distinct responses across different channels, consistent with the sampling of different plasma regions relative to the q = 1 surface. The forward source-tracing simulations reproduce the channel-dependent spatial birth distributions in the poloidal plane and yield pitch angle distributions in good agreement with the measured data. These results demonstrate both the feasibility of the PD diagnostic and the fidelity of the modeling, highlighting the system’s preliminary spatially resolving capability for D–D fusion protons in HL-3 plasmas. The combined diagnostic modeling approach offers a promising framework for studying fast-ion redistribution and MHD-induced modulations of fusion reactivity in future HL-3 discharges.
We simulated proton collective flows in Au + Au collisions at a beam energy of 1.23A GeV using the isospin-dependent quantum molecular dynamics model. We applied the event-plane method to calculate the first- to fourth-order flow coefficients in different v_2 classes, studying the correlations among them. Nearly all event classes satisfy the scaling relation v_3∝ v_1v_2 . Quadrangular flow v_4 also approximately follows the scaling relation v_4 = 0.5 v_2^2 . Additionally, we calculated the Pearson correlation coefficients between the first to fourth harmonic flows for protons, thereby quantifying the inter-harmonic correlations. The Pearson linear correlation coefficient corr(v_n,ε _n) between each flow harmonic and the corresponding eccentricity under different centralities is also examined.
Accelerator-driven system (ADS) is widely regarded as the most effective transmutation solution for nuclear waste. The Monte Carlo transport simulation of full-energy-range particles involved in both the spallation target and subcritical blanket forms the foundation of ADS simulation studies. Based on the Monte Carlo simulation programs OpenMC and GMT, a program named MATS was developed, which integrates reactor physics analysis and high-energy particle simulation capabilities for studying the ADS target-reactor system. The physical calculation functions of the program rely on an electromagnetic interaction module, a hadronic interaction module, a high-energy cross-section module, traditional reactor-oriented calculation functions, and nuclear data library. This equips MATS with the capability to simulate the transport processes of particles in a wide-energy range, which is essential for the R D of ADS because there will be an underestimation of neutron fluence and heat density at the level of more than 10
Accurate assessment of proton and neutron fluxes in the lunar surface radiation environment is essential to ensure the safety of astronauts and instruments, while also supporting mission design and risk mitigation. This study evaluates the capability of the Cs2LiYCl6:Ce (CLYC) detector to detect thermal neutrons and protons, with an emphasis on its possible application for lunar missions. A controlled mixed field of high-energy protons and thermal neutrons, intended to approximate selected aspects of lunar surface irradiation, was generated using the IBA Proteus Plus proton therapy system at the Proton Therapy Center of Hebei Yizhou Cancer Hospital (China). Proton pencil beams with incident energies of 70, 80, 90, and 100 MeV were directed onto an aluminum foil to attenuate the proton flux reaching the detector system, while thermal neutrons were generated by proton interaction with a downstream RW3 solid water phantom. The conventional pulse shape discrimination (PSD) method, relying on charge integration via the tail-to-total method, was found to be ineffective in distinguishing between thermal neutrons and protons under the present dynamic range conditions. A novel approach was introduced that leverages the distinctive characteristics of the falling edges in the waveforms of thermal neutrons and protons, providing a time-domain method for discrimination. The present work assesses the advantages and limitations of the CLYC detector for lunar surface radiation measurements and proposes directions for further improvement.
The operational envelope of high-power-density systems, such as particle accelerators and advanced nuclear energy systems, is critically constrained by the need to manage extreme thermal loads. To address this, we present a novel hybrid optimization framework combining a genetic algorithm (GA) with a soft actor-critic (SAC) deep reinforcement learning agent. This framework was applied to a practical high-heat-flux problem: redesigning the beam dump at the Facility for Rare Isotope Beams (FRIB) for a power upgrade from 20 kW to 50 kW. The resulting design, validated by three-dimensional conjugate heat transfer simulations, suppresses hazardous hot spots and yields a markedly more uniform temperature distribution. This provides a robust operating margin, increasing the average power-handling capability by 72
