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Anderson, A.C. Smith, Terry Lee 2011-06-29T14:45:40Z 2011-06-29T14:45:40Z 10000-01-01 1979 Systematic low-temperature measurements of the thermal conductivity, specific heat, dielectric constant, and temperature-dependent ultrasound velocity have been made on a single piece of vitreous silica. These measurements were repeated after fast neutron irradiation of the material. It was found that the irradiation produced changes of the same relative magnitude in the low-temperature excess specific heat C , the thermal conductivity K, ex and the anomalous temperature dependence of the ultrasound velocity Deltav/v. A corresponding change in the temperature dependent dielectric constant was not observed. It is therefore likely that K and Deltav/v are determined by the same localized excitations responsible for C , but the temperature dependence of the dielectric constant may have a different, though possibly related, origin. Furthermore, a consistent account for the measured C , K, ex and Deltav/v of unirradiated silica is given by the tunneling-state model with a single, energy-dependent density of states. Changes in these three properties due to irradiation can be explained by altering only the density of tunneling states incorporated in the model. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-29T14:45:40Z No. of bitstreams: 1 1979_Smith.pdf: 5449893 bytes, checksum: bd472bf664c9576eeb342ade4bf45015 (MD5) Made available in DSpace on 2011-06-29T14:45:40Z (GMT). No. of bitstreams: 1 1979_Smith.pdf: 5449893 bytes, checksum: bd472bf664c9576eeb342ade4bf45015 (MD5) Previous issue date: 1979 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-06-29T14:45:40Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:16:39-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 397342 http://hdl.handle.net/2142/25562 en Copyright 1979 Terry Lee Smith Neutron irradiation Low-energy excitations Vitreous silica Thermal conductivity Specific heat Dielectric constant Ultrasound velocity The effect of neutron irradiation on the density of low-energy excitations in vitreous silica Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.