Nuclear instruments & methods in physics research section b-beam interactions with materials and atoms vol:65 issue:1-4 pages:223-227
Ultrasonic measurements in neutron-irradiated quartz are carried out for an intermediate dose of 2.6 x 10(19) 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 PBAR and gamma(1) 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 PBAR with the dose was found. This behaviour, however, is not followed by a higher dose, situated near the "threshold regime".