HIGH B/T INSTALLATION

The High B/T Facility is located in the third Bay of the Microkelvin Laboratory at the University of Florida. The University of Florida provided funds for constructing the building that consisted of three separate bays. The completion of the third bay as a high capacity nuclear refrigerator was part of the NHMFL proposal in 1990. The Facility was completed for user operation in 1994-95.

SPECIAL FEATURES AT HIGH B/T

The refrigerator:
Unlike the two other cryostats in the Microkelvin Laboratory, the refrigerator is equipped with a 5-mole PrNi5 nuclear demagnetization stage. The combination of a large circulation refrigeration (Oxford 700) and the PrNi5 stage provides much higher cooling capacity than the copper refrigerators but at the price a much higher base temperature (~250 µK) because of the nuclear ordering in PrNi5.

The magnet System:
The magnet system consists of three interconnected superconducting magnets,

  1. An 8 T magnet for the nuclear demagnetization
  2. A 15-17 T magnet for the experimental region
  3. A shielding system that holds the field constant in the experimental region (to within 100 ppm) during demagnetization.

Turnaround Time:
Unlike conventional nuclear cooling refrigerators, the dewar can be dropped while the magnet system is kept at 4 Kelvin. Bay3’s newly developed system not only reduce turnaround time drastically, but also saves helium consumption during sample change or repair.


SCHEMATIC OF VERTICAL SECTION THROUGH THE HIGH B/T FACILITY


COMPARISON OF B/T CAPABILITIES IN DIFFERENT LABORATORIES IN THE WORLD