Ultrasonic Attenuation in Fused Silicia at High Frequencies and Low Temperatures

Measurements of the attenuation of longitudinal and transverse sound waves of frequencies between 30 MHz and 29 GHz were carried out at temperatures from 1.1 K to 10 K in fused silica. In the upper temperature sange the attenuation can be described by relaxation processes. The absorption at lower temperature is compared with current theories. It is found that our high frequency data are not in a satisfactory agreement with these theories