THERMAL-CONDUCTIVITY OF THE SUPERCONDUCTING AL SI 1-PERCENT ALLOY BELOW 1.2 K/

The thermal conductivity of the Al/Si 1% alloy was investigated in the 0.05-1.2 K temperature range. A critical temperature, T-c similar or equal to 1.2 K, was measured. Below T-c, a k proportional to exp(-b/T) law was determined down to T similar or equal to 0.3 K. Near T = 0.23 K, an inflexion in k suggests a resonant phonon-dislocation interacti on. For T < 0.15 K, a k = lambda T-n was found with n = 2.04 +/- 0.04 and lambda = (1.3 +/- 0.1) (mW/Kcm). Except for this low temperature r ange, in which data practically overlap those of pure Al, k(Alloy) is much smaller than K-Al (a, factor of 100 at 0.2 K). Wires (typically, circle divide = 25 mu m) made of this alloy are widely used in the wed ge bonding of cryogenic detectors. These wires contribute to or determ ine the thermal conductance between the detector and the thermal bath.