Low-Temperature Thermal Conductivity in Neutron Irradiated Vitreous Silica

Abstract

Measurements of the thermal conductivity, K, of vitreous silica have been made at low temperatures before and after fast neutron bombardment. The observed increase of K upon bombardment is in agreement with the prediction of Klemens. Over the exposure range used, K increases approximately linearly with dose to the level used (6×1019 n/cm2) whereas the density appears to have nearly saturated, suggesting that the two properties are not directly related. A possible explanation for the K increase upon bombardment is that the neutron bombardment relieves macroscopic strains. Alternatively, it is possible that bombardment causes an increase in local order in the vitreous material.