HYPER-Q SINGLE-CRYSTAL RESONATORS.

It is possible to obtain resonators with Qs of 10**1**1 at temperatures of 1. 8 degree K and frequencies of the order of tens of megahertz. An increase in the Q of piezoelectric resonators with an increase in frequency has been observed at liquid-helium temperature. Investigations of the acoustic properties of these hyper-Q resonators have shown that the scattering of the elastic waves on defects in the surface layer of the single crystal is very important. The use of special method of processing these surfaces enables us to avoid losses in the surface layer, which are more than 3 to 4 orders of magnitude greater than the losses in the quartz itself.