Published a new paper from N.i.P.S Laboratory: *Low-frequency internal friction in silica glass, EPL 80 50008, 2007*

**You can download the paper here**

If you want to cite this article, please use the following:

*Low-frequency internal friction in silica glass, F. Travasso et al 2007 EPL 80 50008*

** F. Travasso1,2, P. Amico1,2, L. Bosi1,2, F. Cottone1,2, A. Dari1,2, L. Gammaitoni1,2, H. Vocca1,2 and F. Marchesoni2,3,4**

1 Dipartimento di Fisica, Università di Perugia - I-06123 Perugia, Italy

2 Istituto Nazionale di Fisica Nucleare, VIRGO Project Sezione di Perugia - I-06123 Perugia, Italy

3 Dipartimento di Fisica, Università di Camerino - I-62032 Camerino, Italy

4 Michigan Center for Theoretical Physics, The University of Michigan - Ann Arbor, MI 48109-1120, USA

*Precise low-frequency internal friction measurements on vitreous silica, taken over a wide temperature (4 K<T<300 K) and frequency range (40 Hz<f<14 kHz), show remarkable similarities, but also suggestive differences with recent light scattering experiments. In the interval 30 K<T<110 K, the exponent of the power law relaxational spectrum turns out to be proportional to T-Tk, with a minimum at around Tk=13 K. This phenomenon is interpreted as a manifestation of thermal activation in an asymmetric double well system, the asymmetry being associated to quenched spatial disorder. For T>160 K the loss angle develops a distinct step-like structure followed by a plateau, both independent of the exponent, thus signalling the onset of a competing relaxation mechanism with much higher an activation energy.*