Investigation of violin mode Q for wires of various materials

The Q factors of violin modes for wires of various materials have been measured in order to determine which would be most suitable for use in the suspension of test masses in the initial laser interferometer gravitational wave observatory (LIGO) interferometers. A "guitar" type apparatus was employed to measure violin mode Qs, and losses due to clamping and other practical sources were successfully suppressed below the level of intrinsic wire losses. Steel music wire was found to give the highest extrapolated Q factors under LIGO conditions among the wires we tested. This extrapolated Q sets a target for the LIGO suspension which can be attained if all the losses other than the intrinsic wire loss are successfully suppressed. The measured es for the steel, tungsten, and titanium wire, which were approximately frequency independent for the first two to three modes, were found to be roughly proportional to the square root of the tension in the wire. This is consistent with the theory of violin mode losses due to frequency-independent intrinsic wire losses. (C) 1997 American Institute of Physics.