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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 15 of 15 for “"Helium ions"”.
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Study of LaBr3 (Ce) detector response to high energy helium ions
… the LaBr3 scintillator in the presence of heavy ions to provide more accurate measurements of the gamma fields within such a complex radiation environment. A series of Monte-Carlo simulations using MCNP/X version 2.6 have been performed along with a series of experiments using the Heavy Ion …
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Investigating the dynamics of ion-surface interactions using electron-spin-polarized positively charged helium ions
… specifically using electron-spin-polarized 4He+ ions coupled with energy-resolved measurements of the polarization of ejected electrons, are providing significant insight into surface electronic states and the dynamics of the neutralization of charged particles at clean and adsorbate-covered …
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Low ion dose imaging in the Helium Ion Microscope under Neyman Type A statistics
The Helium Ion Microscope (HIM) is a new tool capable of imaging at resolutions not possible in the ubiquitous Scanning Electron Microscope (SEM). However, along with this improvement in imaging, the helium ions used in HIM cause greater damage to samples. Reducing ion doses decreases the amount of …
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GRAPHENE NANOSTUCTURING WITH THE HELIUM ION MICROSCOPE
… INTEREST FOR GRAPHENE?S POTENTIAL APPLICATIONS. HOWEVER, THE CONVENTIONAL FABRICATION TECHNIQUES, ARE EITHER LIMITED BY THE LITHOGRAPHIC RESOLUTION OR LIMITED TO FIXED GEOMETRIES. OUR GROUP HAS DEMONSTRATED A RESIST-FREE DIRECT PATTERNING METHOD TO MAKE SUB-10-NM ARBITRARY FEATURES ON …
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INVESTIGATION OF ELECTRIC AND THERMOELECTRIC PROPERTIES OF GRAPHENE NANORIBBON
… to fabricate ultra-narrow GNRs which is called helium ion Lithography (HIL) using helium ion microscope (HIM). Suspended GNRs with widths down to 5nm and supported GNRs with widths down to 20nm are patterned by directly modifying graphene strips through surface sputtering by helium ions. The …
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The Influence of Defects on the Vibrational and Electronic Properties of the Quasi 1D van der Waals Magnet CrSBr
… to explore the electron-phonon interactions in CrSBr. We find that the electron-phonon coupling is strongly polarized along the b-crystallographic axis, confirming the presence of a quasi-1D electronic structure. We then investigate the influence of defects on the vibrational and …
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Enabling the simulation of helium transport in lithium for fusion devices
… still receive surface damagefrom hydrogen and helium ions. Using flowing lithium to shield the tungsten divertor may reduce the surface damage to the solid divertor. Lithium also has a positive effect on the confinement of the plasma. To more fully understand the interactions of lithium with …
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Nanostructured Origami (TM) : stress-engineering of nanopatterned membranes to produce three-dimensional structures
… substrates with a series of material depositions, etches and lithography steps. These processes are inherently planar and well suited for the fabrication of billions of micrometer-thick transistors over 300 mm diameter substrates, but impractical for building vertically. This thesis presents …
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Deuterium Retention and Trapping in Polycrystalline Tungsten under Simultaneous Implantation of Deuterium with Helium and with Neon
… melt during the deuterium-tritium phase of operations. Helium production from DT fusion reactions will influence W surface roughness, and D and T retention in the W. Neon is a candidate for radiative cooling, to prevent melting, however little research exists on its effects on D retention in W. …
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F-TRIDYN: A Monte-Carlo, BCA code for modeling ion-surface interactions with rough materials and coupling plasma and material codes
… materials. Fractals also have simple relationships to other models of surface roughness, including RMS roughness. This link has been studied and used to approximate fractal surfaces with normally-distributed statistical surfaces, which may prove more computationally efficient than explicit …
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Sub-10-nm lithography with light-ion beams
… of apparatus around the Schottky source. Light ions are an attractive intermediary between electrons and heavy ions in terms of exposure efficiency and resolution by attaining a minimal interaction volume within the resist layer, if only we had bright sources of these light ions and could thus …
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Interaction of plasmas with lithium and tungsten fusion plasma facing components
… a certain temperature range to large fluxes of helium ions. These nanostructures if disrupted into the plasma as dust by an off-normal event would cause quenching of the plasma from the generated dust. Liquid lithium, meanwhile, has gathered growing interest within the fusion community in recent …
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Computer Calculations of Cross Sections for Electron Impact Ionization of Helium
Triple differential cross sections for electron-impact ionization of helium are calculated in the distorted wave approximation. The distorted wave formalism is discussed for the z-axis parallel to the momentum transfer direction. Problems associated with programming this formalism are outlined. The …
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Anwendung des in-beam PET Therapiemonitorings auf Präzisionsbestrahlungen mit Helium-Ionen
… ist somit erforderlich. Die Positronen-Emissions-Tomographie (PET), die normalerweise dazu benutzt wird, die Verteilung eines injizierten Positronenemitters im Gewebe zu bestimmen, kann hier eingesetzt werden. Durch Kernreaktionen der einfliegenden Kohlenstoffionen mit Atomkernen des Gewebes …
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Radiation biophysical modeling of the FLASH effect: from mechanistic understanding towards clinical endpoint prediction
… in animals, e.g., no severe fibrotic lesions on mini pig skin. UHDR electron irradiation was successfully tested in a first patient with cutaneous lymphoma. Furthermore, the first clinical trial with proton-FLASH irradiation is ongoing. In addition to that, the FLASH effect has been …