MECHANICAL LOSS IN FIBERS FOR LOW-NOISE PENDULUMS

We describe measurements of the quality factors of resonances in fiber s made of tungsten, silicon, sapphire, and fused quartz. The silicon a nd sapphire samples exhibited losses consistent with thermoelastic dam ping. Our fused quartz samples showed excess loss at some frequencies. The tungsten fibers had quality factors much lower than the thermoela stic prediction at all frequencies that we measured. We calculate the expected Brownian motion of pendulums made with similar fibers.