He in Obtaining Ultra-Low Temperatures at the NHMFL High B/T Facility*

The High B/T Facility at the National High Magnetic Field Laboratory (NHMFL) provides access to unique ultra-low temperature, high magnetic field and ultra-quiet environments. The facility operates nuclear demagnetization refrigerators capable of reaching 0.5 mK at 16 T and 0.1 mK at 8 T. This enables user experiments in diverse fields including ultrasound studies, FQHE studies in tilted fields, high sensitivity NMR, high sensitivity dielectric measurements, sub-mK susceptibility measurements, novel states (Bose glass, Wigner crystals) and studies of superfluid ³He. These experiments require that the ³He, the electrical leads and samples be efficiently cooled to ultra-low temperatures. In this talk I will discuss the use of liquid ³He in cooling at the High B/T Facility, experimental platforms developed to make best use of this method, recent experimental results obtained, and potential future developments.