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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 60 for “"Atomic number"”.
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Reconstructing the Atomic Number of Cargo X-ray Images using Dual Energy Radiography
… elemental analysis of cargo contents due to the atomic number dependence of photon attenuation. This work investigates the capabilities and limitations for atomic number discrimination using dual energy MeV systems, finding that different materials can sometimes produce identical photon …
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Theoretical Study of the Auger Effect in the Light to Medium Range of Atomic Number
Made available in DSpace on 2015-05-12T17:11:54Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 0011532.PDF: 4454789 bytes, checksum: af98297fb3d104de106deface9bbc3af (MD5) Previous issue date: 1955
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Calculation of the effective atomic number for the iodine contrast agent of the varying concentrations
… by the author. A method of the effective atomic number mapping is discussed as a viable alternative to the traditional attenuation-based tomography. The dependency of the effective atomic number of the compound on the energy of the x-ray beam is a phenomenon well recorded in the …
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Average atomic number and electron density analysis with computerized axial tomography : experimental and computational feasibility studies
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering.
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X-ray Radiative Signatures Influenced by Nonthermal Effects in High-Energy-Density Laboratory Plasmas of Mid-Atomic-Number Z-pinches
… plasma environments with broad application to atomic physics, astrophysics, and HED laboratory physics, including inertial confinement fusion (ICF), making it an inimitable tool for interdisciplinary science. Spectroscopic examination of plasma radiation can yield robust information on plasma …
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Yield, Kinetic Energy, Pairing Effect, and Shell Effect of Light Fission Products for Thermal-Neutron Fission of Uranium-233
… of 0.3%, a mass resolution of 0.5 amu, and an atomic-number resolving power of 38. The yields were measured as a function of mass number, atomic number, and kinetic energy. Detailed comparison shows that the present results are in good agreement with the evaluated yield data (ENDF/B-V). …
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Dual energy image reconstruction and systems for application in proton therapy treatment planning
… dependent on the electron density and effective atomic number of the material and describes the energy loss per unit length in the tissue. In current clinical practice, the SPR of patient tissues is obtained through single energy CT (SECT) scanning. The SECT scan results in a map of kilovoltage …
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Exploring poly (2, 5) benzimidazole enhanced with carbon nanotubes for space applications
… radiation is essential on any space mission. Low atomic number materials, such as hydrogen, have shown to be effective in shielding ionising radiation. However, compared to metallic alloys, these materials suer from relatively low mechanical and thermal properties, which limit their application. …
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Interactions of nucleons: their role in understanding the sun's origin, composition, and source of energy
… as three-dimensional (3-D) plots of mass or atomic number versus charge density versus average energy per nucleon"--Abstract, page iv.
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Using a superconducting cyclotron to detect special nuclear material through multiple monoenergetic gamma radiography and o-axis photon scattering/
… a technique for reconstructing the eective atomic number (Z) and areal density ([rho][subscript A]) of cargo mock-ups using MMGR with the cyclotron, analyzes the sensitivity of the reconstruction technique, and applies the technique to experimental data. However, single-axis radiography is …
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Quantitative evaluation of image quality in CT imaging using iodine and nanoparticle-based contrast agents
… research has increasingly focused on high atomic number nanoparticles, such as bismuth and tantalum, which offer strong X- ray attenuation with reduced toxicity, making them promising alternatives to conventional iodine agents. Objective: The aim was to evaluate the potential of Bismuth …
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The effect of cadmium on some enzymes in the developing chick embryo
… (Cd) possesses the following physical constants: Atomic number 48; atomic weight 112.4; valency 2 and specific gravity a.?. The metal melts at 321°C and boils at ?65°c, and is remarkably volatile for a heavy metal. Its volatility has constituted a special industrial hazard since its b.p. is below …
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Improving ion beam therapy treatment planning for metal implants by using dual-energy CT scanning
… to compute the electron density and effective atomic number. It could already be shown that this additional material information enables a more precise calculation of ion ranges. This thesis investigates the feasibility of the DECT approach for a range of metals from aluminum (Z = 13) up to …
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Optimizing tensor contractions for nuclear correlation functions
… reveal interesting physical properties of atomic nuclei, including ground state energies and scattering potentials. However, calculating their values is computationally intensive due to the fact that the number of terms from quantum chromodynamics in a nuclear wave function scales …
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Spectroscopic radiography with monoenergetic neutrons for homeland security applications
… hydrogenous materials and those of higher atomic number. These dependencies result in characteristic spectral details of hydrogenous materials which may be analyzed to classify type and areal density of cargo contents. The studies presented here demonstrate that this technique is feasible …
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Multiple Monoenergetic Gamma Radiography (MMGR) using compact superconducting cyclotron
… to measure the areal density and the effective atomic number (Zeff) of an object with accuracy that surpasses existing interrogation methods and other major deployed systems. This radiography system was designed using an ION-12SC compact superconducting 12 MeV proton cyclotron. Using a specially …
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Application of density functional theory and machine learning in the prediction of efficient catalysts for the oxidative coupling of methane with reduced CO2 production at low temperature
… the Fermi energies of the catalyst promoter, its atomic number and the bandgaps of the bimetallic oxide and the catalyst support emerged as effective descriptors. Specifically, in relation to the C2y predictive model, C2y increases with an increase in dataset features, including the number of …
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Measurements of magnetoresistance in amorphous alloys
… coupling on the conductivity increases with the atomic number of components. The data are discussed in terms of the theories of magnetoresistance of interacting and noninteracting three-dimensional electron gases in the presence of a disordered potential. Although neither localization nor …
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Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors
… Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis …
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Predicting the Distribution Coefficient of Solvent Extraction of Rare Earth Elements Based on the Gibbs Free Energy and Thermodynamic Theory for Equilibrium Constant
… lanthanides deviates linearly according to their atomic number. However, the yttrium position based on the ionic radius is between holmium and erbium. Many experimental results revealed that the intercept position of yttrium in log D vs. pH plot was between holmium and erbium. Based on the mean …
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