Acoustic Properties of an Amorphous Silica Oscillator at mK Temperatures: Proceedings of the Symposium on Quantum Fluids and Solids, QFS2003

Author： Nazaretski E. Merithew R. D. Pohl R. O. Parpia J. M.

Publisher： Springer Publishing Company

ISSN： 0022-2291

Source： Journal of Low Temperature Physics, Vol.134, Iss.1-2, 2004-01, pp. : 407-412

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Abstract

We have studied the acoustic behavior of an a-SiO₂ composite torsional oscillator in the temperature range between 1 and 100 mK. At higher temperatures, the acoustic properties of amorphous solids are well described by the ‘tunneling model’. However, below 10 mK it was found that the resonance exhibited a non-Lorentzian shape and was highly distorted by random ‘noise’. We attribute this stochastic noise—‘transients’ to interactions of a-SiO₂ with ambient 'y quanta present in the laboratory. By shielding the cryostat with a 5 cm thick lead wall we were able to reduce the number of transients. On the other hand, a deliberately introduced 6.1μCi ²²Na source of γ radiation caused the opposite effect. We interpret the transients in the framework of local heating caused by the interaction between photons and amorphous SiO₂ which changes the elastic properties of the oscillator. Our findings have potential applications for particle detection.