Nuclear Science and Techniques最新文献

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.

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.

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 hotspot 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 (^circ hbox {C}). 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.

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},textrm{MHz}) with a tuning range of ({3.2},textrm{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},textrm{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}^circ) phase difference between two standing wave points in the conditioning system was necessary. Notably, the maximum continuous wave power surpassed ({20},textrm{kW}), exceeding the expected target.

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 (mathrm m^2, text{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(^circ) 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.

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^circ)) 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.

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.

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.

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 with hard probes of jets, open heavy flavor particles, and (Upsilon) production. The EMCal detector, which covers the pseudo-rapidity region of (|eta | le 1.1), is an essential subsystem of sPHENIX. In this study, we focused on producing and testing EMCal blocks covering a pseudo-rapidity of (|eta | in [0.8, 1.1]). These, in conjunction with the central pseudo-rapidity EMCal blocks, significantly enhance the sPHENIX physics capability of the jet and (Upsilon) 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.

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.