Measurements of the ultrasonic attenuation and velocity variation in neutron irradiated quartz for an intermediate dose of 2.6x1019 n/cm2

Ultrasonic measurements in neutron-irradiated quartz are carried out for an intermediate dose of 2.6x1019 n/cm2. The variation of the velocity of sound has been measured and previous attenuation measurements are extended to temperatures below 1.2 K. The TS-parameters anti P and γ1 are calculated from numerical fittings to the tunneling model. The obtained values continue the tendency of previous measurements for lower neutron doses, where a linear increase of anti P with the dose was found. This behaviour, however, is not followed by a higher dose, situated near the ''threshold regime''. (orig.)