High quality factor measured in fused silica

TL;DR

This study measured the mechanical dissipation in fused silica rods, achieving a record-high quality factor of 57 million at room temperature, with surface handling significantly affecting the results.

Contribution

It reports the highest room temperature quality factor in fused silica to date, demonstrating the importance of surface condition on mechanical dissipation.

Findings

Q factor of 57 million at 726 Hz

Surface handling affects Q by a factor of 3-4

Pristine surface yields higher Q values

Abstract

We have measured the mechanical dissipation in a sample of fused silica drawn into a rod. The sample was hung from a multiple-bob suspension, which isolated it from rubbing against its support, from recoil in the support structure, and from seismic noise. The quality factor, Q, was measured for several modes with a high value of 57 million found for mode number 2 at 726 Hz. This result is about a factor 2 higher than previous room temperature measurements. The measured Q was strongly dependent on handling, with a pristine flame-polished surface yielding a Q 3-4 times higher than a surface which had been knocked several times against a copper tube.