THERMAL-PROPERTIES OF MOLYBDENUM BELOW 1 K WITH APPLICATION TO ULTRACRYOGENIC RESONANT-MASS GRAVITATIONAL-WAVE DETECTORS

Measurements of the thermal conductivity and specific heat of commerci al 99.95% purity annealed polycrystalline molybdenum in the temperatur e range of 0.1-1 K are reported. These thermal data and other publishe d data on molybdenum and aluminum-magnesium alloys are used to calcula te and compare cool-down and steady state thermal response of 1 kHz ul tracryogenic resonant-mass gravitational wave detectors made of these materials. At temperatures below 100 mK, the Mo is shown to be far sup erior to the 5056 Al-Mg alloy with regard to temperature homogeneity i n the resonant mass at the expected levels of residual heat leak. (C) 1997 American Institute of Physics.