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Quantitative Analysis of Cerium-Gallium Alloys Using a Hand-Held Laser Induced Breakdown Spectroscopy Device
摘要： A hand-held laser-induced breakdown spectroscopy device was used to acquire spectral emission data from laser-induced plasmas created on the surface of cerium-gallium alloy samples with Ga concentrations ranging from 0–3 weight percent. Ionic and neutral emission lines of the two constituent elements were then extracted and used to generate calibration curves relating the emission line intensity ratios to the gallium concentration of the alloy. The Ga I 287.4-nm emission line was determined to be superior for the purposes of Ga detection and concentration determination. A limit of detection below 0.25% was achieved using a multivariate regression model of the Ga I 287.4-nm line ratio versus two separate Ce II emission lines. This LOD is considered a conservative estimation of the technique’s capability given the type of the calibration samples available and the low power (5 mJ per 1-ns pulse) and resolving power (λ/?λ = 4000) of this hand-held device. Nonetheless, the utility of the technique is demonstrated via a detailed mapping analysis of the surface Ga distribution of a Ce-Ga sample, which reveals signi?cant heterogeneity resulting from the sample production process.
关键词： LIBS,plasma spectroscopy,analytical chemistry,nuclear forensics,nuclear chemistry,lanthanide spectroscopy
更新于2025-09-12 10:27:22
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A silicon quantum-dot-coupled nuclear spin qubit
摘要： Single nuclear spins in the solid state are a potential future platform for quantum computing, because they possess long coherence times and offer excellent controllability. Measurements can be performed via localized electrons, such as those in single atom dopants or crystal defects. However, establishing long-range interactions between multiple dopants or defects is challenging. Conversely, in lithographically defined quantum dots, tunable interdot electron tunnelling allows direct coupling of electron spin-based qubits in neighbouring dots. Moreover, the compatibility with semiconductor fabrication techniques may allow for scaling to large numbers of qubits in the future. Unfortunately, hyperfine interactions are typically too weak to address single nuclei. Here we show that for electrons in silicon metal–oxide–semiconductor quantum dots the hyperfine interaction is sufficient to initialize, read out and control single 29Si nuclear spins. This approach combines the long coherence times of nuclear spins with the flexibility and scalability of quantum dot systems. We demonstrate high-fidelity projective readout and control of the nuclear spin qubit, as well as entanglement between the nuclear and electron spins. Crucially, we find that both the nuclear spin and electron spin retain their coherence while moving the electron between quantum dots. Hence we envision long-range nuclear–nuclear entanglement via electron shuttling. Our results establish nuclear spins in quantum dots as a powerful new resource for quantum processing.
关键词： entanglement,hyperfine interaction,nuclear spins,quantum dots,silicon,coherence times,quantum computing
更新于2025-09-12 10:27:22
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Recent Developments in Dual-Laser Digital Holography for Plasma-Facing Surface Characterization
摘要： A digital holography device is currently undergoing development at the Oak Ridge National Laboratory for the purpose of measuring surface topography, with the goal of deployment as a real-time plasma-facing component diagnostic for the study of materials that could be utilized in a nuclear fusion device. The holography system utilizes one or two lasers depending on the scale of surface features under measurement. Measurements of surface roughness were performed in a single-laser mode and compared with the data from profilometry, with a linear correlation of increased holographic measurement fidelity as surfaces became smoother. Characterization of the dual-laser operating mode has been performed via surface measurement of stainless steel targets with “stair-step” features in various sizes. Results demonstrated that surface features with known sizes as small as 25.4 μm could be resolved. Measurements were within ～55 μm or less deviation from the actual sizes, and measurement accuracy was improved as feature size was increased, corresponding to the effect of noise becoming less pronounced. A target exposed to plasma generated by an electrothermal (ET) arc source was analyzed with flat-field correction and averaging of sequential image frames to demonstrate the improved measurement quality in preparation for future use of holography on ET arc-exposed targets.
关键词： plasma-facing component interaction (PMI),Digital holography (DH),plasma (PFC),plasma-material diagnostic,nuclear fusion
更新于2025-09-12 10:27:22
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Lightning-Rod Effect of Plasmonic Field Enhancement on Hydrogen-Absorbing Transition Metals
摘要： The plasmonic enhancement of electromagnetic ?eld energy density at the sharp tips of nanoparticles or nanoscale surface roughnesses of hydrogen-absorbing transition metals, Pd, Ti, and Ni, is quantitatively investigated. A large degree of energy focusing is observed for these transition metals in the microwave region, even surpassing the enhancement for noble metals according to the conditions. Pd, for instance, exhibits peak ?eld enhancement factors of 6000 and 2 × 108 in air for morphological aspect ratios of 10 and 100, respectively. Metal surfaces possibly contain such degrees of nano- or micro-scale native random roughnesses, and, therefore, the ?eld enhancement e?ect may have been unknowingly produced in existing electrical and optical systems. In addition, for future devices under development, particularly in hydrogen-related applications, it is desirable to design and optimize the systems, including the choice of materials, structures, and operating conditions, by accounting for the plasmonic local energy enhancement e?ect around the metal surfaces.
关键词： nuclear fusion,sensing,transition metal,surface plasmon,nanophotonics,energy device,hydrogen storage,nanoparticle
更新于2025-09-12 10:27:22
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New infrared imaging diagnostic for the Neutral Beam Heating System at the TJ-II stellarator
摘要： An upgraded infrared imaging system has been installed at the stellarator TJ-II as a diagnostic tool of the Neutral Beam Injection heating. Thermographic analysis of the beam-wall interaction areas can be used to estimate the beam power lost through reionization and shine-through mechanisms in Neutral Beam heated plasmas. Three di?erent Regions of Interest inside TJ-II vacuum vessel have been determined whose thermographic analysis will be applied to the study of beam related processes. The optical conditions required for each application have been used to de?ne the speci?cations of the IR camera. Optimization of the optical design has been carried out by means of the optical simulation code ZEMAX. The IR window size has been increased to maximize the fraction of the ?eld of view that is free from vignetting. The system has been fully commissioned and is now operative, routinely providing thermographic data of the regions of interest during the last TJ-II experimental campaign. The IR diagnostic is described in detail and its applicability to study beam power deposition on di?erent targets is discussed.
关键词： Plasma diagnostics - high speed photography,Nuclear instruments and methods for hot plasma diagnostics,Beam Optics,Plasma diagnostics - interferometry, spectroscopy and imaging
更新于2025-09-12 10:27:22
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Design of Energy Recovery Linac for a Source of High-Flux Gamma-ray by Laser Compton Scattering
摘要： We investigate the generations of a high-?ux γ-ray beams by laser Compton scattering. We performed the design of an energy recovery linac that produces a γ-ray beam with the ?ux of ～ 1013 photons/s. It is important to examine the e?ects on beam performances of the ERL in detail. Thus, we examined the e?ects of emittance growths on higher order modes in the superconducting linac and coherent synchrotron radiation in the designed lattice of the energy recovey linac. They were checked by performing the start-to-end simulation of multi-beam particle trackings in the designed 355 MeV ERL. It was shown that the energy recovery linacs by laser Compton scattering may provide monochromatic high-?ux gamma-ray beams. It is shown through our design studies that goals of γ-ray beam parameters in the ERL facility are achievable. Such an energy-tunable γ-ray beams that are generated by laser Compton scattering may be applied to nuclear resonance ?uorescence(NRF) measurements for the non-destructive detection of radioactive nuclear materials. The investigations show that our design studies provide a good optimized ERL parameters in terms of beam dynamics.
关键词： Supercavity,High-?ux gamma rays,Laser Compton scattering,Nuclear resonance ?uorescence,Energy recovery linac
更新于2025-09-12 10:27:22
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Analysis of a Ni-Fe-Cr-Mo-Si hardfacing alloy manufactured by laser cladding: influence of the iron content on the wear resistance properties
摘要： In this article, we present an ongoing study on a Ni-Fe-Cr-Mo-Si based alloy, as one of the potential cobalt free hardfacing materials. Here, we analyze the effect of the variation of iron content on microstructure and wear property that is induced by a controlled dilution the 316L substrate, or by direct addition. First, we present the state of the art on the proposed Ni-Cr-Mo-Si based alloy. Then, the laser cladding setup is presented and the process parameter map search of the Ni-Fe-Cr-Mo-Si based alloy too. Then, iron is added to the base Ni-Cr-Mo-Si alloy by direct fusion of the powders coming from two different powder feeders and directly blended into the coaxial nozzle used. Finally the samples are analyzed in iron content, microhardness and microstructure. The tribology tests of the samples exhibit a clear change in wear behavior with the iron content and an improvement at a certain level of iron.
关键词： Tribology,Nickel Base Alloys,Laser Cladding,Hardfacing Materials,Nuclear Energy,Wear resistance
更新于2025-09-12 10:27:22
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Precision Measurement of Atomic Isotope Shifts Using a Two-Isotope Entangled State
摘要： Atomic isotope shifts (ISs) are the isotope-dependent energy differences between atomic electron energy levels. These shifts have an important role in atomic and nuclear physics, and have been recently suggested as unique probes of physics beyond the standard model under the condition that they are determined significantly more precisely than the current state of the art. In this Letter, we present a simple and robust method for measuring ISs by taking advantage of Hilbert subspaces that are insensitive to common-mode noise yet sensitive to the IS. Using this method we evaluate the IS of the 5S1=2 ? 4D5=2 transition between 86Srt and 88Srt with a 1.6 × 10?11 relative uncertainty to be 570 264 063.435(5)(8) (statistical)(systematic) Hz. Furthermore, we detect a relative difference of 3.46e23T × 10?8 between the orbital g factors of the electrons in the 4D5=2 level of the two isotopes. Our method is relatively easy to implement and is indifferent to element or isotope, paving the way for future tabletop searches for new physics, posing interesting prospects for testing quantum many-body calculations, and for the study of nuclear structure.
关键词： atomic isotope shifts,entangled state,nuclear structure,quantum many-body calculations,precision measurement,new physics
更新于2025-09-12 10:27:22
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Comparison of Perioperative Parameters in Femtosecond Laser-assisted Cataract Surgery using Three Nuclear Fragmentation Patterns
摘要： Purpose: To compare the perioperative parameters of quadrant, sextant, and grid lens fragmentation patterns in femtosecond laser-assisted cataract surgery (FLACS). Design: Prospective randomized clinical trial. Methods: Setting: Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. Patient or Study Population: A total of 894 eyes in 661 patients with cataracts were enrolled. Intervention or Observation Procedures: The nuclear density was graded according to the Emery-Little classification. Patients received lens fragmentation using a quadrant, sextant, or grid pattern after random allocation. Evaluations included intraoperative parameters, complications, and postoperative outcomes. Main Outcome Measure(s): Effective phacoemulsification time (EPT), intraoperative complications, visual acuity and intraocular pressure (IOP) at one day postoperatively, as well as endothelial cell density (ECD), endothelial cell loss (ECL) and central corneal thickness (CCT) at one week postoperatively. Results: In grade 1 nuclei, the mean EPT in the grid group was the shortest compared to those in the quadrant (P = 0.011) and sextant (P = 0.001) groups. In grade 2 nuclei, all three patterns showed no significant difference in the mean EPT (p > 0.05). In grade 3 nuclei, the sextant group revealed shorter mean EPT compared to the grid (P = 0.017) and quadrant (P > 0.05) groups. In grade 4 & 5 nuclei, the quadrant pattern had the shortest mean EPT among all three patterns (P < 0.05). The grid pattern is associated with higher IOP in hard nuclei (grade 4 & 5) than the other two patterns (P < 0.05). Conclusions: The grid and quadrant patterns allow for shorter EPT in soft (grade 1) and hard (grade 4 & 5) nuclei, respectively. All three patterns can be selected for treating grade 2 nuclei. The sextant pattern may be the best option when treating grade 3 nuclei. The grid pattern should be avoided in hard nuclei combined with glaucoma or glaucoma suspect.
关键词： nuclear fragmentation patterns,Femtosecond laser-assisted cataract surgery,Emery-Little classification,perioperative parameters,FLACS
更新于2025-09-12 10:27:22
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Laser-induced dynamics of molecules with strong nuclear quadrupole coupling
摘要： We present a general variational approach for computing the laser-induced rovibrational dynamics of molecules, taking into account the hyperfine effects of the nuclear quadrupole coupling. The method combines the general variational approach TROVE (Theoretical Ro-Vibrational Energies), which provides accurate rovibrational hyperfine energies and wavefunctions for arbitrary molecules, with the variational method RichMol, designed for generalized simulations of the rovibrational dynamics in the presence of external electric fields. We investigate the effect of the nuclear quadrupole coupling on the short-pulse laser alignment of a prototypical molecule CFClBrI, which contains nuclei with large quadrupole constants. The influence of the nuclear quadrupole interactions on the postpulse molecular dynamics is negligible at early times, for the first several revivals; however, at longer time scales, the effect is entirely detrimental and strongly depends on the laser intensity. This effect can be explained by dephasing in the laser-excited rotational wavepacket due to irregular spacings between the hyperfine-split nuclear spin states across different rotational hyperfine bands.
关键词： laser-induced dynamics,nuclear quadrupole coupling,rovibrational dynamics,hyperfine effects,molecular alignment
更新于2025-09-12 10:27:22