The effect of neutron irradiation on the density of low-energy excitations in vitreous silica

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Smith, Terry Lee

Contributors dc:contributor

• Anderson, A.C.

• Neutron irradiation
• Low-energy excitations
• Vitreous silica
• Thermal conductivity
• Specific heat
• Dielectric constant
• Ultrasound velocity

Statement dc:rights

• Copyright 1979 Terry Lee Smith

Language dc:language

en

Identifier

397342

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25562