Study of Heat Links for a Cryogenic Laser Interferometric Gravitational Wave Detector

Heat links are used in order to cool mirrors of Large-scale Cryogenic Gravitational wave telescope (LCGT). In order to evaluate the mirror fluctuation of vibration caused by the heat link, we have measured the size effect about thermal conductivity of pure aluminum and copp er wires and their mechanical losses and Young's moduli at low temperature. By this measurement we can design the noise intro duced from the heat link made sufficiently small by using reasonably a large number of wires with small diameter as the heat link.