Abstract A room-temperature method is developed to measure the intrinsic secondary electron yield (SEY) of gases and liquids physiosorbed on a metal surface, overcoming the limitation of the traditional requirement for cryogenic cooling. By fitting the time-resolved SEY during initial film growth to a derived exponential saturation model, the bulk SEY of the condensed medium is extracted. The method is validated on a Cu substrate for N 2 and CO 2 , yielding SEY curves and fitting parameters in close agreement with cryogenic reference data. The deviations observed for H 2 O are attributed to structural differences between room-temperature adsorption and cryogenic ice, and the SEY spectrum of C 2 H 5 OH is reported for the first time. The technique further serves as a highly sensitive probe for in-situ film thickness measurement. The method can serve as a convenient and inexpensive tool for monitoring nanofilm growth on metal surfaces.

(TiZrNbWAlx)C high-entropy carbides coatings with varying Al contents were fabricated by reactive magnetron co-sputtering by adjusting the Al target power from 0 to 120 W. The microstructure, mechanical properties, and tribological behavior of the coatings were systematically investigated. The results demonstrate that Al addition effectively promotes coating densification and facilitates a structural evolution from an amorphous to a face-centered cubic (fcc) nanocrystalline phase. Concomitantly, the coating hardness exhibited a non-monotonic dependence on Al content, initially decreasing from 9.5 GPa (0 W) to 6.9 GPa (90 W) due to reduced residual stress and formation of the fcc phase, before recovering to 7.7 GPa (120 W) as a result of decrease in sp2-C content and increased residual stress. Remarkably, an optimal Al content was identified, which yielded a superior combination of a low friction coefficient ( 0.22) and an ultra-low wear rate of 4.4 × 10−7 mm3·N−1·m−1. This work elucidates the critical role of Al in modulating the structure–property relationships in (TiZrNbWAlx)C systems and highlights their significant potential as high-performance protective coatings.

This work proposes a novel dual-scintillator anticoincidence (AC) detection system consisting of a front-layer LYSO auxiliary scintillator and a rear 1" & times;1" LaBr3(Ce) main detector, designed for high-resolution low-energy gammaray spectroscopy in mixed-field environments by mitigating Compton scattering, charged particle interference, and intrinsic background. Geant4 simulations identified that a 3 mm-thick, 68 mm-diameter LYSO layer achieves the optimal overall system performance by suppressing 91.50% of charged-particle interference and improving the peak-to-Compton ratio (PCR) by 42.4% for Cs-137 and by 45.6% under "Cs-137 + Sr-90" mixed-field conditions compared to the standalone LaBr3(Ce) detector. Experimental validation with multiple gamma sources (0.511-1.33 MeV) and mixed beta-gamma radiation fields confirmed the simulation results. With an optimized 130 ns AC time window, the system exhibited improved spectral purity and reliable Gaussian fits, the energy resolution (ER) at 662keV improved to 3.26%, and further to 3.21% under mixed-field conditions. In the challenging "Cs-137 + 90Sr" environment, the AC detection system enhanced the PCR to 2.0696 and the peak-to-total ratio (PTR) to 0.4492, corresponding to a peak-to-Compton suppression factor (PCSF) of 9.87 and a peak-to-total suppression factor (PTSF) of 19.79. Moreover, the intrinsic Lu-176 activity in the LYSO crystal, typically a source of interference, was advantageously utilized for in situ self-calibration, enabling accurate background subtraction and stable energy alignment, which ensured reliable PCR and PTR determination. The proposed LYSO-LaBr3(Ce) dual-scintillator AC detection system achieves enhanced ER and superior background suppression, offering a promising solution for high-precision gamma-ray measurements in complex mixedfield environments.

To mitigate pulse saturation and pile-up in a 1”×1” LaBr3(Ce) detection system exposed to intense 3 MeV and 4 MeV γ-ray beams at the Shanghai Laser Electron Gamma Source (SLEGS), this work presents an offline data-processing framework integrating anomalous-event classification and saturated waveform reconstruction. Saturation-affected candidates were preselected from downward-drifting bands in pulse shape discrimination (PSD)-Energy distributions, comprising 28.70% and 25.32% of the raw events, respectively. A secondary fine classification based on first-derivative time-domain features further removed residual pile-up events, yielding single saturated pulses constituting 99.81% and 99.86% of the candidates for subsequent waveform reconstruction. Unsaturated pulses were extracted for average waveform modeling, and a double-exponential (DE) template was identified as the optimal pulse model. An adaptive piecewise weighted nonlinear fitting method reconstructed saturated regions using undistorted rising-edge and tail samples, recovering waveform shape and peak amplitude for mildly to moderately saturated pulses and wide flat-top pulses above 11.4 MeV. Experimental results show that 74.58% and 74.47% of reconstructed events, respectively, achieved low corrected chi-square errors, and more than 99.9% of events within 4.3–11.1 MeV were stably reconstructed. The proposed method extends the reconstructed equivalent-energy range to approximately 27 MeV, corrects the energy-dependent PSD drift, and restores events to a normal pure gamma band centered at 0.343 with a PSD range of 0.329–0.364. The equivalent energy resolutions of the recovered spectra are 44.18% and 40.03%, respectively, outperforming a wide-range unsaturated NaI(Tl) reference detector. Without hardware modification or digitizer-range upgrading, this framework provides a reliable offline data-recovery solution in high-flux gamma-ray measurements.

Fast-neutron response-matrix measurements with organic scintillators require stable energy reconstruction and pulse-shape discrimination (PSD) over a broad recoil-proton signal span. In silicon photomultiplier (SiPM) readout, analog-to-digital converter (ADC) rail saturation biases charge-based energy estimators and distorts PSD observables, limiting the usable dynamic range. A PSD-guided multi-template recovery framework was developed for wide-dynamic-range operation, targeting forthcoming response-matrix measurements for 1–50 MeV neutrons at the China Spallation Neutron Source (CSNS). In this framework, a template dictionary is built by averaging peak-normalized waveforms within PSD-ratio bins. For each rail-saturated waveform, candidate templates are time-aligned at sub-sample resolution, amplitude-scaled, and ranked by the normalized mean squared error (NMSE) computed on the remaining unsaturated samples, with an additional saturation-consistency constraint. Templates are then updated using reliably reconstructed events with mild saturation, followed by a second recovery pass. Validation with a dual-gain deuterium–tritium (DT) neutron measurement shows that, although channel 1 saturates at ∼1.6 MeVee, the proposed recovery extends its effective energy range up to 8.0 MeVee, with the recovered spectrum consistent with the low-gain reference within 1.5–8.0 MeVee; the mean energy deviation of the recovered high-gain channel remains within ∼1% relative to the reference. Neutron–gamma PSD classification accuracy exceeds 99.08% after recovery. The method restores saturated pulses with high fidelity within the empirically validated range of Rpeak ≥ 18% under the present detector and readout configuration.

High count rate neutron measurements require fast signal outputs and effective neutron-gamma discrimination techniques, yet the wide pulse widths generated by silicon photo-multipliers (SiPM) arrays often limit their efficiency in such settings. In prior work, we developed a compensation network (CN) to reduce pulse width and overshoot in SiPM fast outputs, improving pulse shape discrimination (PSD). However, further enhancement was needed to achieve optimal neutron-gamma discrimination. Conventional methods like charge comparison method (CCM) and frequency gradient analysis (FGA) typically analyze either time-domain or frequency-domain features independently. In this study, we employ a deep neural network (DNN) that integrates both frequency and time-domain features from ultra-fast pulse signals to improve discrimination accuracy. We optimized DNN model inputs through a systematic variable selection strategy that included separation ranking, correlation analysis, and recursive feature elimination (RFE), reducing the input set from 73 to 27 variables for a balance of simplicity and discriminative power. The neutron-gamma discrimination was then quantified with an equivalent figure of merit (FOM). Testing with the 252Cf source demonstrated the superior performance of the DNN-based approach, achieving an FOM of 0.96 (98.8% discrimination probability) compared to 0.73 (95.7%) for CCM and 0.63 (93.0%) for FGA. These findings underscore the potential of enhanced ultra-fast signal output systems for nuclear detection in high-count-rate applications.

In recent years, plastic scintillators with pulse shape discrimination (PSD) capability have been widely used in neutron detection when coupled with silicon photomultipliers (SiPMs). The China Spallation Neutron Source (CSNS) offers a valuable experimental platform for response matrix measurements of plastic scintillators over a broad neutron energy range, facilitating their application to high-energy neutron detection. Since the response matrix at CSNS is derived using time-of-flight (TOF) techniques, high timing precision is required to accurately resolve neutron energies. In addition, the pulsed neutron beam at CSNS exhibits high instantaneous flux, which demands that the detector produce sufficiently narrow output pulses to reduce pulse pile-up and ensure stable operation at high count rates. Although the fast output of SiPMs provides superior timing performance and significantly narrower pulse widths than the standard output, the pronounced undershoot following the main pulse limits its applicability in high-count-rate environments. Building upon our previous design of a compensation network (CN), this study systematically evaluates the effects of CN parameter tuning and SiPM bias voltage on the timing characteristics of a plastic scintillator detector. Under an overvoltage of 4.1 V, the optimized CN circuit achieved a coincidence timing resolution with a standard deviation of 0.306 ns, demonstrating good repeatability. Further increasing the overvoltage to 4.9 V resulted in the best timing performance, yielding a coincidence timing resolution of 0.287 ns with similarly good repeatability. These findings provide technical support for high-resolution neutron response measurements at CSNS.

The ionization of the Cu K shell by collisions of C4+ ions at energies ranging from 20 MeV to 50 MeV is studied, and the K x-ray spectra of Cu are measured using an HPGe detector. The relationship between the relative intensity ratio of K beta and K alpha x rays emitted from Cu and the kinetic energy of incident ions is investigated and compared with data for singly ionized atoms. The results show that the relative intensity ratio of K beta to K alpha x ray of Cu target decreases with the increase of incident ion kinetic energy, and the ratio is larger than the data of singly ionized atoms. The K x- ray production cross section of target atom is calculated by using the thick target crosssection formula, and compared with the results obtained from different theoretical models. The results show that the total production cross sections of K beta and K alpha x ray with the increasing incident ion kinetic energy are in close agreement with the BEA modified model which takes multiple ionization into account.

The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex, particularly in the intermediate energy region, because of the limitation of accelerator and existing theoretical analysis, less systematic researches, incomplete atomic data, and not so high accuracy. The research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce. Helium-like C ions with 15–55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe, Ni, Nb and Mo thick targets. The HpGe detectors are used to measure the K-X ray emission, and the corresponding K-X ray emission cross sections are obtained. Due to the different ionization degrees of the shell layers of various target atoms, the branching intensity ratio of Kβ to Kα X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions, while the branching intensity ratio of K-X rays emitted by Nb and Mo target atoms does not change significantly. The K-X ray emission cross section of target atom is calculated by using the formula of thick target cross section, and compared with the results of different theoretical models and proton. The results show that with the increase of the kinetic energy of helium-like C ions, the total emission cross section of the Kβ and Kα X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization, and the total emission cross section of Kβ and Kα X ray emitted from Nb and Mo target atoms are closest to the theoretical values of PWBA model. When the energy of proton is the same as that of single nucleon C ion, the cross section of K-X ray produced by proton is about three orders of magnitude smaller than that produced by helium-like C ion.

The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex, particularly in the intermediate energy region, because of the limitation of accelerator and existing theoretical analysis, the systematic research is relatively few, the atomic data are incomplete and the accuracy is not high, and the research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce. Helium-like C ions with 15~55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe, Ni, Nb and Mo thick targets. The HpGe detectors are used to measure the K X ray emission, and the corresponding K X ray emission cross sections are obtained. Due to the different ionization degrees of the shell layers of various target atoms, the branching intensity ratio of Kβ to Kα X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions, while the branching intensity ratio of KX rays emitted by Nb and Mo target atoms does not change significantly. The K X ray emission cross section of target atom is calculated by using the thick target cross section formula, and compared with the results of different theoretical models and proton. The results show that with the increase of the kinetic energy of helium-like C ions, the total emission cross section of the Kβ and Kα X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization, and the total emission cross section of Kβ and Kα X ray emitted from Nb and Mo target atoms are most close to the theoretical values of PWBA model. When the energy of proton is the same as that of single nucleon C ion, the cross section of K X ray produced by proton is about 3 orders of magnitude smaller than that produced by helium-like C ion.

Abstract TEPC is the preferred device for measuring microdoses due to its excellent organizational equivalence and high energy response. The most important factor affecting its energy response is the electric field distribution in the avalanche region. This paper uses finite element analysis to examine the electric field distribution of a spherical structure with a sensitive area diameter of 2 cm and a cylindrical structure with a sensitive area of 2 cm × 2 cm. While the spherical structure exhibits better isotropy, it has significant distortions in the electric field at the anode wire end, making compensation optimization complex and hindering miniaturization. Cylindrical structures can compensate for the electric field by adding insulators at the anode wire end. When the insulator diameter is 3mm, the optimal protrusion length into the chamber is also 3mm. This lays the foundation for the miniaturization of TEPCs in subsequent research.

Plastic scintillators with pulse shape discrimination (PSD) capability, when combined with silicon photo-multipliers (SiPMs), enable the development of compact neutron detectors with lower power consumption and insensitivity to magnetic fields. However, the SiPM array has a significantly large pulse width of the output signal, which leads to discrimination difficulties at high counting rates. There are two outputs of a SiPM array: a standard output for energy measurement and a fast output for timing measurement. The pulse width of the standard output signal is in the range of hundreds nanoseconds, while the pulse width of the other one is in the range of tens nanoseconds. Fast output signals have traditionally been considered suitably for fast timing, however utilizing them for PSD has been little explored. In our previous work, we successfully implemented PSD by using fast output signals from a SiPM. Despite the obvious negative overshoot in fast signals, we achieved PSD of fast signals by using longer sampling times. However, this approach was still limited at high counting rates. This study proposes a compensation network for fast output signals, which is composed of a compensation unit consisting of a resistor and a capacitor. This design effectively compensates the overshoot of the fast output and shortens the pulse width from 60 ns to 44 ns. Additionally, it highlights the frequency amplitude differences between the neutron and gamma signals from fast output in the high-frequency component, thus improving the PSD capability of the fast output.

With the development of China’s crewed space mission, the space radiation risk for astronauts is increasingly prominent. This paper describes a simulation of the radiation doses experienced by a Chinese female voxel phantom on board the Chinese Space Station (CSS) performed using the Monte Carlo N-Particle (MCNP) software. The absorbed dose, equivalent dose, and effective dose experienced by the voxel phantom and its critical organs are discussed for different levels of shielding of the Tianhe core module. The risk of space-radiation exposure is then assessed by comparing these doses with the current risk limits in China (the skin dose limit for short-term low-earth-orbit missions) and the NASA figures (National Council on Radiation Protection and Measurements Report No. 98) for female astronauts. The results obtained can be used to guide and optimize the radiation protection provided for manned space missions.

7075铝合金因其优异的各项性能,作为结构部件,广泛应用于航天领域中.航天器空间环境中存在各种辐射粒子,这些粒子会对航天器材料产生不同程度的辐照损伤,对其可靠性构成了巨大的威胁,甚至会导致航天任务失败.通过选取不同剂量下 3 MeV的Fe11+离子辐照 7075 铝合金,采用XRD、AFM和纳米压痕等测试手段对 7075铝合金的辐照损伤进行了研究,分析了辐照前后 7075 铝合金的微观组织、表面形貌和硬度的变化.结果显示,离子辐照后的 7075铝合金未形成新的相,且结构保持完整,表明其具有一定的抗辐照性能.同时,观察表面发现了由级联碰撞演化及表面缺陷扩散导致的山峰状突起,且样品表面粗糙度和突起的分布密度随剂量增加呈先增加后减小的趋势.另外,纳米压痕测试表明,辐照后样品硬度增加,且随剂量增加,硬度逐渐趋于饱和,经分析可知,样品产生辐照硬化是由于辐照缺陷阻碍了位错的滑移导致.

Aiming at the problems of stress concentration and negative Poisson's ratio in the deformation process of the re-entrant structure, a cosine-shaped re-entrant structure negative Poisson's ratio metamaterial is proposed in this paper. By optimizing the inclined beams in the re-entrant structural elements into single cosine, tandem cosine and multiple cosine buckling beams, different configurations of improved re-entrant structural elements are designed. Finite element modeling and quasi-static compression simulations and experiments are carried out for single and periodically arranged re-entrant structures. The results show that the comprehensive stress of the single cosine structure and the tandem cosine structure are reduced by 18.7% and 58%, respectively, and the maximum stress can be reduced by 6.7% and 5.2%, respectively. In addition, the negative Poisson's ratio of metamaterial with a single cosine re-entrant structure is increased by 14% compared with that before the improvement.

X-ray spectra emitted in collisions of 1500 ~ 3500-keV projectile Xeq+ (q = 12-29) ions with medium-Z Fe, Ni, and Cu targets as well as higher-Z Ta targets are reported. Interestingly, the lines from the collisions with higherZ targets are mainly composed of characteristic x rays of target atoms, while those from the collisions with medium-Z targets consist mainly of characteristic x rays of projectile ions and broad molecular-orbital x rays. The origins of all these lines and their charge-state dependence are analyzed in detail within the framework of the transient quasi-molecular states which are formed in the collisions. By analyzing the fluorescence yields and vacancy lifetimes of the collision partners, the reasons for the differences in producing x rays between medium-Z and higher-Z targets are discussed in detail for the first time.

在"立德树人作为教育的根本任务"引领下,文章以"空间环境探测技术"理论课程为例,探索了专业课程与思政教育相结合以及由传统讲授式教学向"以学生为中心"转变的教育教学模式的改革方式.同时,也探讨了教学方法与手段多样化以及线上多资源的利用使得课程具有多元化、多层次感.最终力求使思政教育贯穿课程内容,学生参与度和满意度增加,积极性和主动性提高,人才培养质量也随之提升.

The magnetic manipulation of droplets is one of the emerging magnetofluidic technologies that integrate multiple disciplines, such as electromagnetics, fluid mechanics and so on. The directly driven droplets are mainly composed of ferrofluid or liquid metal. This kind of magnetically induced droplet manipulation provides a remote, wireless and programmable approach beneficial for research and engineering applications, such as drug synthesis, biochemistry, sample preparation in life sciences, biomedicine, tissue engineering, etc. Based on the significant growth in the study of magneto droplet handling achieved over the past decades, further and more profound explorations in this field gained impetus, raising concentrations on the construction of a comprehensive working mechanism and the commercialization of this technology. Current challenges faced are not limited to the design and fabrication of the magnetic field, the material, the acquisition of precise and stable droplet performance, other constraints in processing speed and so on. The rotational devices or systems could give rise to additional issues on bulky appearance, high cost, low reliability, etc. Various magnetically introduced droplet behaviors, such as deformation, displacement, rotation, levitation, splitting and fusion, are mainly introduced in this work, involving the basic theory, functions and working principles.

We applied the thermal spike model to interpret the interplay of the kinetic energy with the potential energy in the nanostructures formation of various materials, i.e., the two dimensional freestanding monolayer MoS2, mica, KCl and CaF2, induced by xenon ions for the wide range of the charge state (15+ to 50+) and the kinetic energy from several keV up to 10 MeV. The deposition of the potential energy in the solid is extracted from the non equilibrium charge state distributions when the highly charged ions are transporting in the solids. Also, the experiments of the nanostructure formation on the surfaces of the mica samples induced by Xeq+ (28+ to 35+) at the kinetic energies of 66.7 keV and 288 keV have been performed and the potential energy thresholds for the hillock formation have been measured to support our calculations and explanations. The increase of the damage pore radius as a function of the potential energy has been interpreted for the freestanding monolayer MoS2. For the bulk materials (mica, KCl and CaF2), the interplay of the kinetic energy and the potential energy has been calculated and discussed and the general agreements have been reached between the model calculations and the experimental results.

Purpose Spherical robot plays an essential role in the field of mobile robot because of its unique shape and omni-directional mobility, especially in the application of planet detection. Although spherical robot has many advantages over leg robot, its obstacle climbing performance is still not satisfactory, that is exactly the motivation of this paper. The purpose of this paper is to propose a high-performance hopping mechanism for spherical robot, which can adapt to different terrain and effectively cross obstacles. Design/methodology/approach The hopping system uses torque spring as part of the energy storage mechanism, and converts the kinetic energy of rotation into elastic potential energy with a particularly designed turntable. Moreover, the track of the turntable, based on the Archimedes spiral principle, has the attributes of equidistance and equivelocity that enable better stability of energy storage process. Findings Experiments show that the proposed hopping mechanism can make a 250 g spherical robot jump up to 58 cm with the take-off angle of 60°. Finally, the influence of friction and take-off angle on the hopping height and distance of the robot is also analyzed, which provides a prior guidance for optimizing its jumping process. Originality/value This paper shows how to easily design a lightweight, compact and embedded spring hopping structure so that a spherical hopping robot with detection ability can be developed.