Coated fused silica fibers for enhanced sensitivity torsion pendulum for LISA

In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica a factor of 9 lower than obtained with the tungsten fiber used in the recent LISA torsion pendulum study [L. Carbone, et al., Phys. Rev. Lett. 91 (2003) 151101]. This will allow a corresponding increase in sensitivity of torsion pendula used for small force measurements.