- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Study of Lithium Rich Giants with the GALAH Spectroscopic Survey
摘要： In this article, we speculate on the possible mechanisms for Li enhancement origin in RGB stars based on a large data set of around 340 299 stars collected from the GALAH survey combined with the Gaia astrometry. Data has 51 982 low mass (M ≤ 2 M(cid:3)) RGB stars with reliable atmospheric parameters. The data set shows a well-populated RGB with well-defined luminosity bump and red clump with significant number of stars at each of these two key phases. We found 335 new Li-rich RGB stars with Li abundance, A(Li) ≥ 1.80 ± 0.14 dex, of which 20 are super Li-rich with A(Li) ≥ 3.20 dex. Most of them appear to be in the red clump region which, when combined with stellar evolutionary time-scales on RGB, indicates that the Li enhancement origin may lie at RGB tip during He-flash rather than by external source of merging of sub-stellar objects or during luminosity bump evolution. Kinematic properties of sample stars suggest that Li-rich giants are relatively more prevalent among giants of thin disc compared to thick disc and halo.
关键词： stars: abundances,surveys,abundances,nucleosynthesis,Hertzsprung-Russell and colour-magnitude diagrams,stars: kinematics and dynamics,stars: evolution,nuclear reactions
更新于2025-09-19 17:15:36
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Letter to the Editor: A response to Hruska’s case study on molecular breast imaging and the need for true tissue quantification
摘要： We applaud the efforts by Hruska et al. to quantify differences in tissue using molecular breast imaging (MBI) and background parenchymal uptake (BPU); we have discussed the use of such previously [2]. The approach while commendable did not provide diagnostically useful information to differentiate tissue types. This approach, like the utilization of standardized uptake value (SUV), compares differences in background with tissue [3]. As we have already discussed [2, 4, 5] in the literature, this approach is an incorrect model, due to (1) the critical lack of standardization and calibration of nuclear cameras including both SPECT/Planar and PET; (2) the utilization of ratios which are not absolute values and therefore cannot be used to differentiate tissue based upon those issues, critical to the understanding of tissue differences; and (3) the inability to truly 'measure' transitional changes in tissue, which would allow for the determination of actual treatment response on a per patient basis, saving time, money, and lives.
关键词： Patent protected,AI,Breast cancer,FMTVDM??,Theranostics,Quantification,B.E.S.T. Imaging??,Nuclear camera quantitative calibration,Breast inflammation
更新于2025-09-19 17:15:36
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Testing requirements for active interrogation systems
摘要： The role of active-interrogation systems for nuclear security is to detect the presence of special nuclear material inside an object by observing the radiation emitted by that object when it has been exposed to known sources of external radiation. Because of the cost, complexity, and the need to avoid irradiating occupants, active-interrogation systems are intended for cargo applications where shielding can prevent detection by passive radiation detection systems. To ensure that active-interrogation systems for detection of special nuclear material are designed and tested to a consistent level of performance, technical standards are needed for evaluating such systems. This paper addresses the testing standards needed for active-interrogation systems to detect high atomic number materials, fissionable materials, and specific special nuclear materials. Because the use of special nuclear material for a testing standard is not practical, this work focuses on the determination of materials that could be used as surrogates in that they provide a similar response as targets of special nuclear materials. The results of this paper, determined through analytic calculations and radiation transport modeling, are based upon scenarios constructed and applied to specific active-interrogation modalities.
关键词： High-Z,Nuclear resonance fluorescence,Active interrogation,Differential die-away,Photofission
更新于2025-09-19 17:15:36
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180 Gb/s PAM8 Signal Transmission in Bandwidth-Limited IMDD System Enabled by Tap Coefficient Decision Directed Volterra Equalizer
摘要： At the request of the Domestic Nuclear Detection Office (DNDO), a Study Committee comprised of representatives from the American Physical Society, Panel on Public Affairs, the IEEE, and Nuclear and Plasma Sciences Society performed a technical review of the DNDO Transformational and Applied Research Directorate (TARD) R&D program. TARD’s principal objective is to address gaps in the Global Nuclear Detection Architecture (GNDA) through improvements in the performance, cost, and operational burden of detectors and systems. The charge to the Study Committee was to investigate the existing TARD R&D plan and portfolio, recommend changes to the existing plan, and recommend possible new R&D areas and opportunities. This report is the result of an independent, detailed analysis of the current R&D plan and includes, for each application area, observations, and recommendations to focus future investments within the context of the TARD mission.
关键词： nuclear forensics,Algorithms and modeling,shielded nuclear materials,radiation detection
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Fill Factor Loss in Fielded Photovoltaic Modules Due to Metallization Failures, Characterized by Luminescence and Thermal Imaging
摘要： During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young’s modulus was calculated and its radial pro?le was correlated to the corresponding burnup pro?le and to the hardness radial pro?le data obtained by Vickers micro-indentation
关键词： Nuclear fuels,piezoelectric devices,Vickers microhardness,Young’s modulus,nuclear power
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - In-situ Microscopy Characterization of Cu(In,Ga)Se <sub/>2</sub> Potential-Induced Degradation
摘要： During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young’s modulus was calculated and its radial pro?le was correlated to the corresponding burnup pro?le and to the hardness radial pro?le data obtained by Vickers micro-indentation
关键词： Nuclear fuels,piezoelectric devices,Vickers microhardness,Young’s modulus,nuclear power
更新于2025-09-19 17:13:59
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Radiology, Lasers, Nanoparticles and Prosthetics || 2. Nuclei and isotopes
摘要： In Chapters 5 to 12 nuclear methods in medicine are discussed either for imaging (scintigraphy, SPECT, PET) or for radiation treatment of cancerous tissues (proton and neutron irradiation, brachytherapy). It is therefore appropriate to first introduce some basic properties of nuclides and isotopes, and in particular of radioactive isotopes which are used in nuclear medicine. This chapter is not intended to replace a textbook on nuclear physics. But it provides sufficient background information for better understanding the subsequent chapters. Handling of radiation in general and application of radioactive isotopes also requires a detailed knowledge of radiation dose and radiation safety, which are topics of Chapter 4.
关键词： scintigraphy,medicine,SPECT,neutron irradiation,PET,brachytherapy,radiation safety,proton irradiation,nuclides,cancerous tissues,isotopes,radioactive isotopes,radiation dose,imaging,nuclear medicine,nuclear methods,radiation treatment
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Rough and Straightforward Estimation of the Mismatching Loss by Partial Shading of the PV Modules Installed on an Urban Area or Car-Roof
摘要： During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young’s modulus was calculated and its radial pro?le was correlated to the corresponding burnup pro?le and to the hardness radial pro?le data obtained by Vickers micro-indentation
关键词： Nuclear fuels,piezoelectric devices,Vickers microhardness,Young’s modulus,nuclear power
更新于2025-09-19 17:13:59
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High-resolution laser resonance ionization spectroscopy of $$^{143-147}$$143-147Pm
摘要： We present the results of high-resolution laser spectroscopy of the long-lived radioactive isotopes 143?147Pm. The hyper?ne structures and isotope shifts in two different atomic ground-state transitions at 452 nm and 468 nm were probed by in-source laser spectroscopy at the RISIKO mass separator in Mainz, using the PI-LIST ion source. From the hyper?ne coupling constants the nuclear magnetic dipole and electric quadrupole moments for 143?147Pm were derived, and the measured isotope shifts allowed the extraction of changes in nuclear mean square charge radii.
关键词： hyper?ne structures,nuclear magnetic dipole,electric quadrupole moments,high-resolution laser spectroscopy,isotope shifts,nuclear mean square charge radii
更新于2025-09-19 17:13:59
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Surface Morphological Features of Molybdenum Irradiated by a Single Laser Pulse
摘要： Molybdenum (Mo) is considered a plasma facing material alternative to tungsten (W) for manufacturing the divertor armours of International Thermonuclear Experimental Reactor (ITER). Transient thermal loads of high energy occurring in a tokamak during the service life have been simulated through a single laser pulse delivered by a Nd:YAG/Glass laser, and the effects have then been examined through scanning electron microscopy (SEM) observations. An erosion crater forms in correspondence with the laser spot due to the vaporization and melting of the metal, while all around a network of cracks induced by thermal stresses is observed. The findings have been compared to results of similar experiments on W and literature data. The morphology of the crater and the surrounding area is different from that of W: the crater is larger and shallower in the case of Mo, while its walls are characterized by long filaments, not observed in W, because the lower viscosity and surface tension of Mo allow an easier flow of the liquid metal. Most importantly, the volume of Mo ablated from the surface by the single laser pulse is about ten times that of W. This critical aspect is of particular relevance and leads us to conclude that W remains the best solution for manufacturing the armours of the ITER divertor.
关键词： laser,nuclear fusion reactors,surface damage,molybdenum,microstructure
更新于2025-09-19 17:13:59