Vol.35,

The Circular Electron Positron Collider (CEPC) is designed to precisely measure the properties of the Higgs boson, study electroweak interactions at the Z-boson peak, and search for new physics beyond the Standard Model. As a component of the 4^th Conceptual CEPC detector, the drift chamber facilitates the measurement of charged particles. This study implemented a Geant4-based simulation and track reconstruction for the drift chamber. For the simulation, detector construction and response were implemented and added to the CEPC simulation chain. The development of track reconstruction involved track finding using the Combinatorial Kalman Filter method and track fitting using the tool of GenFit. Using the simulated data, the tracking performance was studied. The results showed that both the reconstruction resolution and tracking efficiency satisfied the requirements of the CEPC experiment.

567

The BL07U beamline is a new extreme ultraviolet and soft X-ray beamline housed in the Shanghai Synchrotron Radiation Facility. Beamlines are used in nano-resolved angle-resolved photoemission spectroscopy (Nano-ARPES), spin-resolved angle-resolved photoemission spectroscopy (Spin-ARPES), X-ray magnetic circular dichroism spectroscopy, and X-ray magnetic linear dichroism spectroscopy for certain scientific research. The BL07U beamline, which is based on a pair of elliptical polarized undulators and a variable-included-angle plane-grating monochromator, delivers circularly or linear polarized X-rays within the energy range of 50–2000 eV. The beamline features two branches: one dedicated to Nano-ARPES, which has a minimum spot size of only ~ 200 nm, and another branch comprising Spin-ARPES, a vector magnetic field, and superconductive magnetic end-station.

729

Accurate measurement of the transverse position of a beam is crucial in particle accelerators because it plays a key role in determining the beam parameters. Existing methods for beam-position measurement rely on the detection of image currents induced on electrodes or narrow-band wake field induced by a beam passing through a cavity-type structure. However, these methods have limitations. The indirect measurement of multiple parameters is computationally complex, requiring external calibration to determine the system parameters in advance. Furthermore, the utilization of the beam signal information is incomplete. Hence, this study proposes a novel method for measuring the absolute electron beam transverse position. By utilizing the geometric relationship between the center position of the measured electron beam and multiple detection electrodes and by analyzing the differences in the arrival times of the beam signals detected by these electrodes, the absolute transverse position of the electron beam crossing the electrode plane can be calculated. This method features absolute position measurement, a position sensitivity coefficient independent of vacuum chamber apertures, and no requirement for a symmetrical detector electrode layout. The feasibility of this method is validated through numerical simulations and beam experiments.

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663

Qiang Li，Li-Jiao Wang，Jing-Yu Tang，Xiang-Biao Qiu，Zhen Chen，Mao-Yuan Zhao，Chang-Jun Ning，Kai Pan，Wei Xu，Tao Li，Su-Peng Lu，Han Yi，Rui-Rui Fan，Chang-Qing Feng，Rong Zhang，Xiao-Yang Sun，Qi An，Hao-Fan Bai，Jiang-Bo Bai，Jie Bao，Ping Cao，Qi-Ping Chen，Yong-Hao Chen，Zeng-Qi Cui，An-Chuan Fan，Fan-Zhen Feng，Min-Hao Gu，Chang-Cai Han，Zi-Jie Han，Guo-Zhu He，Yong-Cheng He，Yang Hong，Yi-Wei Hu，Han-Xiong Huang，Wei Jiang，Zhi-Jie Jiang，Zheng-Yao Jin，Ling Kang，Bo Li，Gong Li，Xiao Li，Yang Li，Jie Liu，Rong Liu，Shu-Bin Liu，Yi-Na Liu，Guang-Yuan Luan，Jie Ren，Zhi-Zhou Ren，Xi-Chao Ruan，Zhao-Hui Song，Kang Sun，Zhi-Xin Tan，Sheng-Da Tang，Jin-Cheng Wang，Peng-Cheng Wang，Zhao-Hui Wang，Zhong-Wei Wen，Xiao-Guang Wu，Xuan Wu，Cong Xia，Yong-Ji Yu，Guo-Hui Zhang，Hang-Chang Zhang，Lin-Hao Zhang，Qi-Wei Zhang，Xian-Peng Zhang，Yu-Liang Zhang，Yue Zhang，Zhi-Yong Zhang，Zhi-Hao Zhou，Ke-Jun Zhu，Chong Zou

Neutron resonance imaging (NRI) has recently emerged as an appealing technique for neutron radiography. Its complexity surpasses that of conventional transmission imaging, as it requires a high demand for both a neutron source and detector. Consequently, the progression of NRI technology has been sluggish since its inception in the 1980s, particularly considering the limited studies analyzing the neutron energy range above keV. The white neutron source (Back-n) at the China Spallation Neutron Source (CSNS) provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV. Neutron-sensitive microchannel plates (MCP) have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions, high detection efficiency, and low noise. In this study, we report the development of a ¹⁰B-doped MCP detector, along with its associated electronics, data processing system, and NRI experiments at the Back-n. Individual heavy elements such as gold, silver, tungsten, and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range; the more difficult medium-weight elements such as iron, copper, and aluminum with resonance peaks in the 1-100 keV energy range can also be identified. In particular, results in the neutron energy range of dozens of keV (Aluminum) are reported here for the first time.

496

The exploration of exotic shapes and properties of atomic nuclei, e.g., α cluster and toroidal shape, is a fascinating field in nuclear physics. To study the decay of these nuclei, a novel detector aimed at detecting multiple α-particle events was designed and constructed. The detector comprises two layers of double-sided silicon strip detectors (DSSD) and a cesium iodide scintillator array coupled with silicon photomultipliers array as light sensors, which has the advantages of their small size, fast response, and large dynamic range. DSSDs couple with cesium iodide crystal arrays are used to distinguish multiple α hits. The detector array has a compact and integrated design that can be adapted to different experimental conditions. The detector array was simulated using Geant4, and the excitation energy spectra of some α-clustering nuclei were reconstructed to demonstrate the performance. The simulation results show that the detector array has excellent angular and energy resolutions, enabling effective reconstruction of the nuclear excited state by multiple α particle events. This detector offers a new and powerful tool for nuclear physics experiments and has the potential to discover interesting physical phenomena related to exotic nuclear structures and their decay mechanisms.

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The octupole deformation and collectivity in octupole double-magic nucleus ¹⁴⁴Ba are investigated using the Cranking covariant density functional theory in a three-dimensional lattice space. The reduced B(E3) transition probability is implemented for the first time in semiclassical approximation based on the microscopically calculated electric octupole moments. The available data, including the I–ω relation and electric transitional probabilities B(E2) and B(E3) are well reproduced. Furthermore, it is shown that the ground state of ¹⁴⁴Ba exhibits axial octupole and quadrupole deformations that persist up to high spins (I≈24ℏ).

397

Qiang Li，Li-Jiao Wang，Xiang-Biao Qiu，Jing-Wen Li，Wei Xu，Tao Li，Ze-Bin Lin，Chang-Jun Ning，Yong-Hao Chen，Rui-Rui Fan，Kang Sun，Jing-Yu Tang，Rong Zhang，Han-Tao Jing，Bo Mei，Qi An，Hao-Fan Bai，Jiang-Bo Bai，Jie Bao，Ping Cao，Qi-Ping Chen，Zhen Chen，Zeng-Qi Cui，An-Chuan Fan，Chang-Qing Feng，Fan-Zhen Feng，Ke-Qing Gao，Min-Hao Gu，Chang-Cai Han，Zi-Jie Han，Guo-Zhu He，Yong-Cheng He，Yang Hong，Yi-Wei Hu，Han-Xiong Huang，Wei-Hua Jia，Hao-Yu Jiang，Wei Jiang，Zhi-Jie Jiang，Zheng-Yao Jin，Ling Kang，Bo Li，Chao Li，Gong Li，Jia-Wen Li，Xiao Li，Yang Li，Jie Liu，Rong Liu，Shu-Bin Liu，Guang-Yuan Luan，Bin-Bin Qi，Jie Ren，Zhi-Zhou Ren，Xi-Chao Ruan，Zhao-Hui Song，Zhi-Xin Tan，Sheng-Da Tang，Peng-Cheng Wang，Zhao-Hui Wang，Zhong-Wei Wen，Xiao-Guang Wu，Xuan Wu，Li-Kun Xie，Yi-Wei Yang，Han Yi，Yong-Ji Yu，Guo-Hui Zhang，Lin-Hao Zhang，Mo-Han Zhang，Qi-Wei Zhang，Xian-Peng Zhang，Yu-Liang Zhang，Yue Zhang，Zhi-Yong Zhang，Mao-Yuan Zhao，Lu-Ping Zhou，Zhi-Hao Zhou，Ke-Jun Zhu

Neutron-sensitive microchannel plates (nMCPs) have applications in neutron detection, including energy spectrum measurements, neutron-induced cross-sections, and neutron imaging. ¹⁰B-doped MCPs (B-MCPs) have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range. Good spatial and temporal resolutions are useful for neutron energy-resolved imaging. However, their practical applications still face many technical challenges. In this study, a B-MCP with 10 mol% ¹⁰B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source. The neutron detection efficiency was calibrated at 1 eV, which is approximately 300 times that of an ordinary MCP and indicates the success of ¹⁰B doping. The factors that caused the reduction in the detection efficiency were simulated and discussed. The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods, and showed very good consistency for neutron energies below tens of keV. The response is more complicated at higher neutron energy, at which point the elastic and non-elastic reactions of all nuclides of B-MCP gradually become dominant. This is beneficial for the detection of neutrons, as it compensates for the detection efficiency of B-MCP for high-energy neutrons.

699

Calcium production and the stellar evolution of first-generation stars remain fascinating mysteries in astrophysics. As one possible nucleosynthesis scenario, break-out from the hot carbon-nitrogen-oxygen (HCNO) cycle was thought to be the source of the calcium observed in these oldest stars. However, according to the stellar modeling, a nearly tenfold increase in the thermonuclear rate ratio of the break-out ¹⁹F(p, γ)²⁰Ne reaction with respect to the competing ¹⁹F(p, α)¹⁶O back-processing reaction is required to reproduce the observed calcium abundance. We performed a direct measurement of this break-out reaction at the China Jinping Underground Laboratory. The measurement was performed down to the low-energy limit of E_c.m. = 186 keV in the center-of-mass frame. The key resonance was observed at 225.2 keV for the first time. At a temperature of approximately 0.1 GK, this new resonance enhanced the thermonuclear ¹⁹F(p, γ)²⁰Ne rate by up to a factor of ≈7.4, compared with the previously recommended NACRE rate. This is of particular interest to the study of the evolution of the first stars and implies a stronger breakdown in their "warm" CNO cycle through the ¹⁹F(p, γ)²⁰Ne reaction than previously envisioned. This breakout resulted in the production of the calcium observed in the oldest stars, enhancing our understanding of the evolution of the first stars.

452

This study proposes a novel particle-encoding mechanism that seamlessly incorporates the quantum properties of particles, with a specific emphasis on constituent quarks. The primary objective of this mechanism is to facilitate the digital registration and identification of a wide range of particle information. Its design ensures easy integration with different event generators and digital simulations commonly used in high-energy experiments. Moreover, this innovative framework can be easily expanded to encode complex multi-quark states comprising up to nine valence quarks and accommodating an angular momentum of up to 99/2. This versatility and scalability make it a valuable tool.

608

The sPHENIX experiment is a new generation of large acceptance detectors at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, with scientific goals focusing on probing the strongly interacting Quark-Gluon Plasma (QGP) with hard probes of jets, open heavy flavor particles, and ϒ production. The EMCal detector, which covers the pseudo-rapidity region of |η|≤1.1, is an essential subsystem of sPHENIX. In this study, we focused on producing and testing EMCal blocks covering a pseudo-rapidity of |η|∈[0.8,1.1]. These, in conjunction with the central pseudo-rapidity EMCal blocks, significantly enhance the sPHENIX physics capability of the jet and ϒ particle measurements. In this paper, the detector module production and testing of sPHENIX W-powder/Scintillating Fiber (W/ScFi) Electromagnetic Calorimeter Blocks are presented. The selection of the tungsten powder, mold fabrication, QA procedures, and cosmic-ray test results are discussed.

674

A charged particle array named MATE-PA, which serves as an auxiliary detector system for a multi-purpose active-target time projection chamber used in nuclear astrophysical and exotic beam experiments (MATE), was constructed. The array comprised of 20 single-sided strip-silicon detectors covering approximately 10% of the solid angle. The detectors facilitated the detection of reaction-induced charged particles that penetrate the active volume of the MATE. The performance of MATE-PA has been experimentally studied using an alpha source and a 36-MeV ¹⁴N beam injected into the MATE chamber on the radioactive ion beam line in Lanzhou (RIBLL). The chamber was filled with a gas mixture of 95% ⁴He and 5% CO₂ at a pressure of 500 mbar. The results indicated good separation of light-charged particles using the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be approximately 1% (σ) for an energy loss of approximately 10 MeV caused by the α particles. The inclusion of MATE-PA improves particle identification and increases the dynamic range of the kinetic energy of charged particles, particularly that of the α particles, up to approximately 15 MeV.

587

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks. In this study, real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps, 12-bit digitizer, and the neutron and gamma spectra were calculated directly on an FPGA. A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2M tokamak at the Southwestern Institute of Physics, China. The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 ms. At count rates of up to 1 Mcps, the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.

653

The evolution of dislocation loops in austenitic steels irradiated with Fe⁺ is investigated using cluster dynamics (CD) simulations by developing a CD model. The CD predictions are compared with experimental results in the literature. The number density and average diameter of the dislocation loops obtained from the CD simulations are in good agreement with the experimental data obtained from transmission electron microscopy (TEM) observations of Fe⁺-irradiated Solution Annealed 304, Cold Worked 316, and HR3 austenitic steels in the literature. The CD simulation results demonstrate that the diffusion of in-cascade interstitial clusters plays a major role in the dislocation loop density and dislocation loop growth; in particular, for the HR3 austenitic steel, the CD model has verified the effect of temperature on the density and size of the dislocation loops.

624

Experimental scratch tests and first-principles calculations were used to investigate the adhesion property of AlCrNbSiTi high-entropy alloy (HEA) coatings on zirconium substrates. AlCrNbSiTi HEA and Cr coatings were deposited on Zr alloy substrates using multi-arc ion plating technology and scratch tests were subsequently conducted to estimate the adhesion property of the coatings. The results indicated that Cr coatings had better adhesion strength than HEA coatings, and the HEA coatings showed brittleness. The special quasi-random structure approach was used to build HEA models, and Cr/Zr and HEA/Zr interface models were employed to investigate the cohesion between the coatings and Zr substrate using first-principles calculations. The calculated interface energies showed that the cohesion between the Cr coating and the Zr substrate was stronger than that of the HEA coating with Zr. In contrary to Al or Si in the HEA coating, Cr, Nb, and Ti atoms binded strongly with Zr substrate. Based on the calculated elastic constants, it was found that low Cr and high Al content decreased the mechanical performances of HEA coatings. Finally, this study demonstrated the utilization of a combined approach involving first-principles calculations and experimental studies for future HEA coating development.

588

Accurate and efficient online parameter identification and state estimation are crucial for leveraging Digital Twin simulations to optimize the operation of near-carbon-free nuclear energy systems. In previous studies, we developed a reactor operation digital twin (RODT). However, non-differentiabilities and discontinuities arise when employing machine-learning-based surrogate forward models, challenging traditional gradient-based inverse methods and their variants. This study investigated deterministic and metaheuristic algorithms and developed hybrid algorithms to address these issues. An efficient modular RODT software framework that incorporates these methods into its post-evaluation module is presented for comprehensive comparison. The methods were rigorously assessed based on convergence profiles, stability with respect to noise, and computational performance. The numerical results show that the hybrid KNNLHS algorithm excels in real-time online applications, balancing accuracy and efficiency with a prediction error rate of only 1% and processing times of less than 0.1 s. Contrastingly, algorithms such as FSA, DE, and ADE, although slightly slower (approximately 1 s), demonstrated higher accuracy with a 0.3% relative L₂ error, which advances RODT methodologies to harness machine learning and system modeling for improved reactor monitoring, systematic diagnosis of off-normal events, and lifetime management strategies. The developed modular software and novel optimization methods presented offer pathways to realize the full potential of RODT for transforming energy engineering practices.

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