Results 251 to 260 of about 337,692 (304)
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Positron profiles and positron annihilation in thin layers
physica status solidi (a), 1982The moderated positron density distribution over the sample depth is properly calculated. The results obtained are used as the basis for the positron annihilation probability in thin foils and surface layers. The annihilation photon angular distribution (APAD) for the double-layer samples is measured.
A. D. Pogrebnyak +2 more
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Positron diffusion in Mo: The role of epithermal positrons
Physical Review B, 1987Positrons at keV energies, incident on Mo(111) are observed to escape the sample prior to thermalization. Analysis of positron back-diffusion data shows that an excess contribution of ``hot'' positronium (Ps) seriously affects positron mobility measurements. Suppressing the ``hot'' Ps fraction the positron diffusion coefficient is shown to vary as ${T}^
, Huomo +3 more
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Probing Biomembranes with Positrons
The Journal of Physical Chemistry B, 2009Free volume pockets inside a cell membrane play a prominent role in a variety of dynamic processes such as the permeability of small molecules across membranes and the diffusion of, e.g., lipids, drugs, and electron carriers in the plane of the membrane.
Petri, Sane +6 more
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Positron-atom and positron-molecule collisions
Physics Reports, 1982Abstract The scattering of positrons by atoms and molecules is reviewed. The recent development of monoenergetic slow positron beams and their applications to the measurement of cross sections for positrons interacting in various gases are discussed briefly.
A.S. Ghosh, N.C. Sil, P. Mandal
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Physics in Medicine and Biology, 1988
The developments in positron emission tomography (PET) are reviewed with an emphasis on instrumentation for clinical PET imaging. After a brief summary of positron imaging before the advent of computed tomography, various improvements are highlighted including the move from PET scanners with septa to fully 3D scanners, changes in the preferred ...
Gerd, Muehllehner, Joel S, Karp
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The developments in positron emission tomography (PET) are reviewed with an emphasis on instrumentation for clinical PET imaging. After a brief summary of positron imaging before the advent of computed tomography, various improvements are highlighted including the move from PET scanners with septa to fully 3D scanners, changes in the preferred ...
Gerd, Muehllehner, Joel S, Karp
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The International Journal of Applied Radiation and Isotopes, 1960
Abstract Short-lived Ga68 can be prepared from its long-lived parent, Ge68, thus providing a convenient source of positron-emitting activity for medical or other applications. Solvent extraction is used for the rapid separation of the gallium daughter and a method for the production of the germanium parent is given.
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Abstract Short-lived Ga68 can be prepared from its long-lived parent, Ge68, thus providing a convenient source of positron-emitting activity for medical or other applications. Solvent extraction is used for the rapid separation of the gallium daughter and a method for the production of the germanium parent is given.
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Annual Review of Neuroscience, 1980
An understanding of disease processes in the human brain must ultimately be based on a knowledge of the underlying regional hemodynamic, metabolic, and biochemical changes. Although some such information is currently available from various animal models, the conflicting nature of these data often leaves many important questions unanswered and ...
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An understanding of disease processes in the human brain must ultimately be based on a knowledge of the underlying regional hemodynamic, metabolic, and biochemical changes. Although some such information is currently available from various animal models, the conflicting nature of these data often leaves many important questions unanswered and ...
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Positron trapping model including spatial diffusion of the positron
Physical Review B, 1985The trapping model for the annihilation rate of positrons implanted in solids has been combined with a diffusion model for the spatial motion of the implanted positrons prior to annihilation. Results are given for a simple system having traps only at the surface of a sample and allowing no detrapping, and for a general case where both effects are ...
, Frieze, , Lynn, , Welch
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Positron-reemission-microscope study of positron implantation and diffusion
Physical Review B, 1991The results of high-resolution laterally resolved measurements of positron implantation and diffusion are presented. High-magnification (4400\ifmmode\times\else\texttimes\fi{}), transmission-mode positron-reemission-microscopic images of a compound sample, which inhibited positron implantation in a well-defined region, were taken for positron ...
, Brandes, , Canter, , Mills
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Positron sources and positron beams
Proceedings of the International School of Physics “Enrico Fermi”In the last decades, a large variety of low-energy positron beams has been built based on β+sources. However, the available maximum intensity of laboratory beams is limited to about 107moderated positrons per second. For this reason, several setups have been developed at large-scale facilities such as electron accelerators and research reactors in
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