Vol.35,

DD4hep serves as a generic detector description toolkit recommended for offline software development in next-generation high-energy physics (HEP) experiments. Conversely, Filmbox (FBX) stands out as a widely used 3D modeling file format within the 3D software industry. In this paper, we introduce a novel method that can automatically convert complex HEP detector geometries from DD4hep description into 3D models in the FBX format. The feasibility of this method was demonstrated by its application to the DD4hep description of the Compact Linear Collider detector and several sub-detectors of the super Tau-Charm facility and circular electron-positron collider experiments. The automatic DD4hep–FBX detector conversion interface provides convenience for further development of applications, such as detector design, simulation, visualization, data monitoring, and outreach, in HEP experiments.

229

The high-intensity heavy-ion accelerator facility (HIAF) is a scientific research facility complex composed of multiple cascade accelerators of different types, which pose a scheduling problem for devices distributed over a certain range of 2 km, involving over a hundred devices. The White Rabbit (WR), a technology-enhancing Gigabit Ethernet, has shown the capability of scheduling distributed timing devices but still faces the challenge of obtaining real-time synchronization calibration parameters with high precision. This study presents a calibration system based on a time-to-digital converter implemented on an ARM-based System-on-Chip (SoC). The system consists of four multi-sample delay lines, a bubble-proof encoder, an edge controller for managing data from different channels, and a highly effective calibration module that benefits from the SoC architecture. The performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0 to 24000 ps with 120000 data for every test. The design presented in this study refines the calibration precision of the HIAF timing system. This eliminates the errors caused by manual calibration without efficiency loss and provides data support for fault diagnosis. It can also be easily tailored or ported to other devices for specific applications and provides more space for developing timing systems for particle accelerators, such as white rabbits on HIAF.

187

A passive neutron multiplicity measurement device, FH-NCM/S1, based on field-programmable gate arrays (FPGAs), is developed specifically for measuring the mass of plutonium-240 (²⁴⁰Pu) in mixed oxide fuel. FH-NCM/S1 adopts an integrated approach, combining the shift-register analysis mode with the pulse-position timestamp mode using an FPGA. The optimal effective length of the ³He neutron detector was determined to be 30 cm, and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations. After fabricating the device, calibration measurements were performed using a ²⁵²Cf neutron source; a detection efficiency of 43.07% and detector die-away time of 55.79s were observed. Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift-register analysis mode and a plutonium-waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency (ε) and double gate fraction (f_d), resulting in corrected double rates (Dc), which were used to validate the accuracy of the shift-register analysis mode. Furthermore, the device exhibited fluctuations in the measurement results, and within a single 20-s measurement, these fluctuations remained below 10%. After 30 cycles, the relative error in the mass of ²⁴⁰Pu was less than 5%. Finally, correlation calculations confirmed the robust consistency of both measurement modes. This study holds specific significance for the subsequent design and development of neutron multiplicity devices.

187

This paper presents a superhydrophobic melamine (ME) sponge (ME-g-PLMA) prepared via high-energy radiation-induced in-situ covalent grafting of long-alkyl-chain dodecyl methacrylate (LMA) onto an ME sponge for efficient oil-water separation. The obtained ME-g-PLMA sponge had an excellent pore structure with superhydrophobic (water contact angle of 154) and superoleophilic properties. It can absorb various types of oils up to 66–168 times its mass. The ME-g-PLMA sponge can continuously separate oil slicks in water by connecting a pump or separating oil underwater with a gravity-driven device. In addition, it maintained its highly hydrophobic properties even after long-term immersion in different corrosive solutions and repeated oil adsorption. The modified ME-g-PLMA sponge exhibited excellent separation properties and potential for oil spill cleanup.

195

The sensitivity of the dark photon search through invisible decay final states in low-background experiments relies significantly on the neutron and muon veto efficiencies, which depend on the amount of material used and the design of the detector geometry. This paper presents the optimized design of the hadronic calorimeter (HCAL) used in the DarkSHINE experiment, which is studied using a GEANT4-based simulation framework. The geometry is optimized by comparing a traditional design with uniform absorbers to one that uses different thicknesses at different locations on the detector, which enhances the efficiency of vetoing low-energy neutrons at the sub-GeV level. The overall size and total amount of material used in the HCAL are optimized to be lower, owing to the load and budget requirements, whereas the overall performance is studied to satisfy the physical objectives.

189

In recent years, the gap between the supply and demand of medical radioisotopes has increased, necessitating new methods for producing medical radioisotopes. Photonuclear reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical radioisotopes. However, the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical radioisotopes. In this study, the entire process of the generation, decay, and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with shielding gamma-ray spectrometer. Based on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source (SLEGS), the feasibility of this measurement of production cross section for surveyed medical radioisotopes was simulated, and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were provided. The feasibility of this method for high precision measurements of the reaction cross section of medical radioisotopes was demonstrated.

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Based on the dinuclear system model, the synthesis of the predicted double-magic nuclei ²⁹⁸Fl and ³⁰⁴120 was investigated via neutron-rich radioactive beam-induced fusion reactions. The reaction ⁵⁸Ca+²⁴⁴Pu is predicted to be favorable for producing ²⁹⁸Fl with a maximal ER cross section of 0.301 pb. Investigations of the entrance channel effect reveal that the ²⁴⁴Pu target is more promising for synthesizing ²⁹⁸Fl than the neutron-rich targets ²⁴⁸Cm and ²⁴⁹Bk, because of the influence of the Coulomb barrier. For the synthesis of ³⁰⁴120, the maximal ER cross section of 0.046 fb emerges in the reaction ⁵⁸V+²⁴⁹Bk, indicating the need for further advancements in both experimental facilities and reaction mechanisms.

195

The Very Large Area gamma-ray Space Telescope (VLAST) is a mission concept proposed to detect gamma-ray photons through both Compton scattering and electron-positron pair production mechanisms, thus enabling the detection of photons with energies ranging from MeV to TeV. This project aims to conduct a comprehensive survey of the gamma-ray sky from a low-Earth orbit using an anti-coincidence detector, a tracker detector that also serves as a low-energy calorimeter, and a high-energy imaging calorimeter. We developed a Monte Carlo simulation application of the detector using the GEANT4 toolkit to evaluate the instrument performance, including the effective area, angular resolution, and energy resolution, and explored specific optimizations of the detector configuration. Our simulation-based analysis indicates that the current design of the VLAST is physically feasible, with an acceptance above 10 m² sr which is four times larger than that of the Fermi-LAT, an energy resolution better than 2% at 10 GeV, and an angular resolution better than 0.2 at 10 GeV. The VLAST project promises to make significant contributions to the field of gamma ray astronomy and enhance our understanding of the cosmos.

251

To validate the design rationality of the power coupler for the RFQ cavity and minimize cavity contamination, we designed a low-loss offline conditioning cavity and conducted high-power testing. This offline cavity features two coupling ports and two tuners, operating at a frequency of 162.5 MHz with a tuning range of 3.2 MHz. Adjusting the installation angle of the coupling ring and the insertion depth of the tuner helps minimize cavity losses. We performed electromagnetic structural and multiphysics simulations, revealing a minimal theoretical power loss of 4.3%. However, when the cavity frequency varied by 110 kHz, theoretical power losses increased to 10%, necessitating constant tuner adjustments during conditioning. Multiphysics simulations indicated that increased cavity temperature did not affect frequency variation. Upon completion of the offline high-power conditioning platform, we measured the transmission performance, revealing a power loss of 6.3%, exceeding the theoretical calculation. Conditioning utilized efficient automatic range scanning and standing wave resonant methods. To fully condition the power coupler, a 15 phase difference between two standing wave points in the conditioning system was necessary. Notably, the maximum continuous wave power surpassed 20 kW, exceeding the expected target.

220

Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage, store energy, and decrease power variation. In this study, DC-link capacitors in pulsed power supplies were investigated. By deriving an analytical method for the capacitor current on the H-bridge topology side, the root-mean-square value of the capacitor current was calculated, which helps in selecting the DC-link capacitors. The proposed method solves this problem quickly and with high accuracy. The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement, and the capacitor’s hot spot temperature and temperature rise are calculated using the FFT transform. The test results showed that the error between the calculated and measured temperature increases was within 1.5 ℃. Finally, the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis. The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.

178

As a complement to X-ray computed tomography (CT), neutron tomography has been extensively used in nuclear engineering, materials science, cultural heritage, and industrial applications. Reconstruction of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0 to 180 degrees and typically takes several hours to complete. Such a low time-resolved resolution degrades the quality of neutron imaging. Decreasing the number of projection acquisitions is an important approach to improve the time resolution of images; however, this requires efficient reconstruction algorithms. Therefore, sparse-view reconstruction algorithms in neutron tomography need to be investigated. In this study, we investigated the three-dimensional (3D) reconstruction algorithm for sparse-view neutron CT scans. To enhance the reconstructed image quality of neutron CT, we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation (SBTV). A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental data. According to the analyzed results, OS-SART-SBTV is superior to the other algorithms in terms of denoising, suppressing artifacts, and preserving detailed structural information of images.

205

The Dynamics beamline (D-Line), which combines synchrotron radiation infrared spectroscopy (SR-IR) and energy-dispersive X-ray absorption spectroscopy (ED-XAS), is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale. This combined technique is effective for investigating rapid structural changes in atoms, electrons, and molecules in complicated disorder systems, such as those used in physics, chemistry, materials science, and extreme conditions. Moreover, ED-XAS and SR-IR can be used independently in the two branches of the D-Line. The ED-XAS branch is the first ED-XAS beamline in China, which uses a tapered undulator light source and can achieve approximately 2.5 × 10¹² photons/s·300 eV BW@7.2 keV at the sample position. An exchangeable polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution. The focused beam size is approximately 3.5 μm (H) × 21.5 μm (V), and the X-ray energy range is 5–25 keV. Using one- and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized. Several distinctive techniques, such as the concurrent measurement of in-situ ED-XAS and infrared spectroscopy, time-resolved ED-XAS, high-pressure ED-XAS, XMCD, and pump–probe ED-XAS, can be applied to achieve different scientific goals.

292

The fast X-ray imaging beamline (BL16U2) at Shanghai Synchrotron Radiation Facility (SSRF) is a new beamline that provides X-ray micro-imaging capabilities across a wide range of time scales, spanning from 100 ps to μs and ms. This beamline has been specifically designed to facilitate the investigation of a wide range of rapid phenomena, such as the deformation and failure of materials subjected to intense dynamic loads. In addition, it enables the study of high-pressure and high-speed fuel spray processes in automotive engines. The light source of this beamline is a cryogenic permanent magnet undulator (CPMU) that is cooled by liquid nitrogen. This CPMU can generate X-ray photons within an energy range of 8.7–30 keV. The beamline offers two modes of operation: monochromatic beam mode with a liquid nitrogen-cooled double-crystal monochromator (DCM) and pink beam mode with the first crystal of the DCM out of the beam path. Four X-ray imaging methods were implemented in BL16U2: single-pulse ultrafast X-ray imaging, microsecond-resolved X-ray dynamic imaging, millisecond-resolved X-ray dynamic micro-CT, and high-resolution quantitative micro-CT. Furthermore, BL16U2 is equipped with various in situ impact loading systems, such as a split Hopkinson bar system, light gas gun, and fuel spray chamber. Following the completion of the final commissioning in 2021 and subsequent trial operations in 2022, the beamline has been officially available to users from 2023.

209

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch (in-vacuum undulator with a 24-mm periodic length) of the energy material beamline (E-line) at the Shanghai Synchrotron Radiation Facility (SSRF). This spectrometer was utilized to implement X-ray emission spectroscopy (XES), high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS), and resonant inelastic X-ray scattering (RIXS). Seven spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles, adopting an area detector to increase the solid angle to 1.75% of 4 π sr, facilitating the study of low-concentrate systems under complex reaction conditions. Operated under the atmosphere pressure, the spectrometer covers the energy region from 3.5 to 18 keV, with the Bragg angle ranging from 73° to 86° during vertical scanning. It offers a promised energy resolution of sub-eV (XES) and super-eV (HERFD-XAS). Generally, these comprehensive core-level spectroscopy methods based on hard X-rays at the E-line with an extremely high photon flux can meet the crucial requirements of a green energy strategy. Moreover, they provide substantial support for scientific advances in fundamental research.

179

The round-beam operation presents many benefits for scientific experiments regarding synchrotron radiation and the weakening influences of intra-beam scattering in diffraction-limited synchrotron light sources. A round beam generation method based on the global setting of skew quadrupoles and the application of a non-dominated sorting genetic algorithm was proposed in this study. Two schemes, including large-emittance coupling introduced via betatron coupling and vertical dispersion, were explored in a candidate lattice for an upgrade-proposal of the Shanghai Synchrotron Radiation Facility. Emittance variations with lattice imperfections and their influence on the beam dynamics of beam optic distortions were investigated. The results demonstrated that a precise coupling control ranging from 10% to 100% was achieved under low optical distortion, whereas full-coupling generation and its robustness were achieved by our proposed method by adjusting the skew quadrupole components located in the dispersion-free sections. The Touschek lifetime increased by a factor of 2 to 2.5.

192

A sustainability-oriented assessment of the nuclear energy system can provide informative and convincing decision-making support for nuclear development strategies in China. In our previous study, four authentic nuclear fuel cycle (NFC) transition scenarios were proposed, featuring different development stages and exhibiting distinct environmental, economic, and technical characteristics. However, because of the multiple and often conflicting criteria embedded therein, determining the top-priority NFC alternative for a sustainability orientation remains challenging. To address this issue, this study proposed a novel hybrid multi-criteria decision-making framework comprising fuzzy AHP, PROMETHEE-GAIA, and MOORA. Initially, an improved fuzzy AHP weighting model was developed to determine criteria weights under uncertainty and investigate the influence of various weight aggregation and defuzzification approaches. Subsequently, PROMETHEE-GAIA was used to address conflicts among the criteria and prioritize alternatives on a visualized k-dimensional GAIA plane. As a result, the alternative for direct recycling PWR spent fuel in fast reactors is considered the most sustainable. Furthermore, a sensitivity analysis was conducted to examine the influence of criteria weight variation and validate the screening results. Finally, using MOORA, some significant optimization ideas and valuable insights were provided to support decision-makers in shaping nuclear development strategies.

172

To further research on high-parameter plasma, we plan to develop a two-dimensional hard X-ray (HXR) imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV. The application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross section. Therefore, it is suitable for the study of fast-electron physics, such as radio-frequency wave current drives, fast electrons driving instabilities, and plasma disruptions in fusion research. In this study, we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4, in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are considered. The preliminary calculation results indicate that the HXR energy deposition on the detector is symmetrically distributed, even though the plasma distribution is asymmetric owing to the toroidal effect. These simulation results are helpful in constructing the relationship between the energy deposition on the detector and parameter distribution on the plasma cross section during HL-3 experiments. This is beneficial for the reconstruction of the fast-electron distribution function and for optimizing the design of the HXR-imaging system.

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