A CRYOMAGNETIC SYSTEM ACHIEVING 17T AND LESS-THAN-3MK

The design and performance of a cryomagnetic facility capable of achie ving a temperature of 3mK in a magnetic field of 17T is presented. Usi ng adiabatic nuclear demagnetisation of a copper stage, a He-3 melting curve thermometer may be cooled to a temperature below 914 mu K, the spin ordering temperature of the solid He-3. The lower end of a silver rod coupled to this stage and extending into a 17T magnetic field coo ls to below 3mK, where tile nuclear heat capacity of the silver is ris ing. The careful design of the vibration isolation of the cryostat red uces the heat leak in full field to below 2nW. This cryostat is curren tly being used for quantum oscillation studies of the heaviest quasipa rticles associated with heavy fermion systems.