نتایج جستجو برای: graphite source
تعداد نتایج: 432876 فیلتر نتایج به سال:
Title of Dissertation: A GAS-INJECTION NEGATIVE ION SOURCE FOR ACCELERATOR MASS SPECTROMETRY Scott Joseph Tumey, Doctor of Philosophy, 2004 Dissertation directed by: Professor Alice C. Mignerey Department of Chemistry & Biochemistry Accelerator mass spectrometry is an ultra-sensitive isotopic analysis technique that allows for the determination of rare long-lived radionuclides such as radiocarb...
Impact diamonds were found in several inipactites from the Ries crater. Geriiiaiiy including fallout and fallback (crater f i l l ) suevites. a glass bomb, impact melt i-ock and shocked gneiss. These diamonds formed two distinct grain size populations: 50-300 pii apographitic. platy aggregates with surface ornamentation and etching that \vere observed using optical and scanning electron microsc...
A theory of the long-wavelength low-energy electronic structure of graphite-derived nanotubules is presented. The propagating p electrons are described by wrapping a massless two dimensional Dirac Hamiltonian onto a curved surface. The effects of the tubule size, shape, and symmetry are included through an effective vector potential which we derive for this model. The rich gap structure for all...
Quasielastic neutron scattering experiments and molecular dynamics ~MD! simulations have been used to investigate molecular diffusive motion near the melting transition of monolayers of flexible rod-shaped molecules. The experiments were conducted on butane and hexane monolayers adsorbed on an exfoliated graphite substrate. For butane, quasielastic scattering broader than the experimental energ...
Related Articles Production of negative ions on graphite surface in H2/D2 plasmas: Experiments and srim calculations Phys. Plasmas 19, 063503 (2012) Electrical shielding box measurement of the negative hydrogen beam from Penning ion gauge ion source Rev. Sci. Instrum. 83, 063302 (2012) Meniscus and beam halo formation in a tandem-type negative ion source with surface production Appl. Phys. Lett...
A development program is underway at the IGISOL (Ion Guide Isotope Separator On-Line) facility, University of Jyväskylä, to efficiently and selectively produce low-energy radioactive ion beams of silver isotopes and isomers, with a particular interest in N=Z Ag. A hot cavity ion source has been installed, based on the FEBIAD (Forced Electron Beam Induced Arc Discharge) technique, combined with ...
For the past seven years a joint research and development effort focusing on the design of steady state, intense ion sources has been in progress with the ultimate goal being to meet the two, energy extreme range needs of mega-electron-volt and 100’s of electron-volt ion implanters. However, since the last Fortier is low energy ion implantation, focus of the endeavor has shifted to low energy i...
A line for preparation of graphite targets for accelerator mass spectrometry (AMS) radiocarbon dating has been built in the Gliwice 14C Laboratory. The AMS 14C measurements of our targets are performed in the Leibniz-Labor für Altersbestimmung, Kiel, Germany. The quality of our line has been tested in two series of AMS 14C measurements of background and Ox-II standard samples and by measurement...
Impact diamonds were found in several inipactites from the Ries crater. Geriiiaiiy including fallout and fallback (crater f i l l ) suevites. a glass bomb, impact melt i-ock and shocked gneiss. These diamonds formed two distinct grain size populations: 50-300 pii apographitic. platy aggregates with surface ornamentation and etching that \vere observed using optical and scanning electron microsc...
The study of structural dynamics of complex macromolecular crystals using electrons requires bunches of sufficient coherence and charge. We present diffraction patterns from graphite, obtained with bunches from an ultracold electron source, based on femtosecond near-threshold photoionization of a laser-cooled atomic gas. By varying the photoionization wavelength, we change the effective source ...
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