Characterisation of mechanical loss in synthetic fused silica ribbons

Synthetic fused silica fibres of rectangular cross section, known as ‘ribbon’ fibres, are currently the baseline design for the suspension elements of the lowest stage of the test mass suspensions for the planned Advanced LIGO detector. In this Letter we present the first measurements of mechanical loss factors of synthetic fused silica ribbons of a type potentially suitable for this purpose and estimate the level of dissipation associated with the surface of the ribbons. We also present measurements of breaking stress which demonstrate that ribbons can have breaking stresses up to 3.7 GPa, giving a significant margin of safety over the proposed 0.76 GPa working load for Advanced LIGO.