Microwave Phonon-Attenuation Measurements in Quartz

Measurements have been made of the temperature dependence of the attenuation at 9000 Mc/sec of two slow transverse, two fast transverse, and three longitudinal phonon modes in "perfect" natural-quartz specimens. The attenuation of the slow transverse waves follows the theory of Landau and Rumer. The attenuation of the longitudinal and fast transverse waves follow the theories of Maris and Shiren, which take into account the finite lifetime of the thermal phonons with which the microwave phonons interact, but some discrepancies still exist in the magnitude of the attenuation. The steps observed in the attenuation of imperfect quartz are identified as two peaks at 16±{}3^∘{}K and 24±{}3^∘{}K, sumperimposed on a phonon-phonon background. Possible mechanisms for these attenuation peaks are discussed.