Ultrasonic study of the tunneling states in neutron-irradiated quartz in the transition region

Abstract

The ultrasonic absorption is measured in neutron-irradiated quartz. The irradiation dose is 8.9×10 19 n/cm 2 ( E⩾0.3 MeV). Due to this irradiation dose, the sample is situated in the transition region between mainly crystalline and fully amorphous quartz. The experiment is carried out as a function of temperature at a frequency of 115 MHz. The results are analyzed in the framework of the tunneling model and the soft potential model. Analysis confirms that the density of states goes through a maximum and also shows that the cross-over temperature from tunneling to thermal activation is rather high.