A time-pulsed positronium beam and a study of oxides on silicon using positrons.
Item
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Title
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A time-pulsed positronium beam and a study of oxides on silicon using positrons.
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Identifier
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AAI9315480
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identifier
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9315480
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Creator
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Khatri, Ravinder Kumar.
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Contributor
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Adviser: Leonard O. Roellig
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Date
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1993
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter | Physics, Radiation
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Abstract
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The studies on rare gas solid moderators were carried out with a 350 {dollar}\mu{dollar}Ci {dollar}\sp{lcub}22{rcub}{dollar}Na radioactive source. The corrected efficiency for neon moderator in conical geometrical configuration was as high as (1.4 {dollar}\pm{dollar} 0.2)%. The conical configuration moderator performed better by a factor of (2.2 {dollar}\pm{dollar} 0.2) than the cylindrical configuration. A time pulsed positron beam was built to carry out investigations on the positronium formation processes and positronium beam. This beam has the capability to store low energy e{dollar}\sp+{dollar} in a magnetic bottle, with a magnetic bottle at one end and an electrostatic mirror at the other. These stored e{dollar}\sp+{dollar} are then bunched to form a pulse with a buncher. The bunched beam had a FWHM of 17 nsec and contained 1 to 2 e{dollar}\sp+{dollar}/pulse. A thin carbon foil of 50 A thickness was used for positronium formation by process of charge exchange. Positronium Annihilation Spectroscopy (PAS) was utilized to carry out studies on the activation energy of hydrogen at the interface of oxide and silicon substrate and the effect of irradiation on the oxides in SiO{dollar}\sb2{dollar}/Si(100) sample. The activation energy of hydrogen at the interface of SiO{dollar}\sb2{dollar}/Si(100) samples with n- and p-type substrate was measured to be 2.60(6) eV and 2.47(6) eV respectively. The investigations of the samples irradiated with x-ray and {dollar}\gamma{dollar}-ray led to the first time identification of creation of E{dollar}\sp\prime{dollar} centers with PAS.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
