9503701 Xiao A packaged commercial dilution refrigerator will be acquired and its usage will be divided among four research projects requiring experiments at millikelvin temperatures. One project studies quantum phase- coherent transport in normal-superconducting metal mesoscopic structures. The new quantum transport phenomenom reveals itself in the low temperature range. A second project investigates semiconductor devices exhibiting quantum transport effects such as resonant tunneling, ballistic transport over macroscopic distances, and Coulomb blockade. Low temperature transport measurements will be performed on semiconductor nanostructures of adjustable dimensionality and lateral extent. A third project will use the dilution refrigerator to test ultra-sensitive millimeter-wave detectors developed to study the background radiation of the universe. To achieve the required sensitivity, these detectors have to be operated at millikelvin temperatures. The fourth project studies phonon propagation in layered compounds and the effects of disorder on the scattering of phonons in crystalline solids at very low temperatures. %%% The acquisition of a single instrument for experiments impacting a wide range of fields is very cost effective. Quantum transport phenomena play an important role in small structures that are the result of the ever- decreasing dimensions of microelectronic devices. ***
