Lancaster University EMP Facilities

The main instruments and support to be made available are:

• Fridge#2.This has been refurbished several times since its construction in the late 1970's. Early experiments on this machine included the study of transport properties in ³He/⁴He solutions and measurements of nuclear spin-lattice relaxation in copper down to 7mK. The fridge has been used in many pioneering experiments on ballistic quasiparticles in superfluid ³He, including various Andreev scattering processes and the development of "black body radiator" techniques. It produced the first 100 mK superfluid ³He NMR experiments and the discovery of the long-lived NMR persistent precessing spin domain. This refrigerator has a custom shaped magnetic field facility which have been used to control the first-order phase transition between the A and B phases of superfluid ³He. Studies have included nucleation properties and the dynamics of the A-B interface. The interface has also been used to simulate the interaction of cosmological m-branes formed in the early Universe.
   
• Fridge#4.Based on a 2.7 mK dilution refrigerator, this small machine routinely cools superfluid ³He to ~100 μK, using Lancaster-style copper nuclear cooling stages. It was used to make the first bolometric particle detection experiments in superfluid ³He-B. Recent experiments have focused on quantum turbulence, including the first direct measurement of Andreev reflection from vortices and the first direct measurements of the energy released by decaying turbulence. A new type of cooling under development based on the nuclear cooling of solid ³He layers coating silica aerogel strands will open up a new regime of superfluid ³He studies at extremely low temperatures where thermal excitations are almost completely absent.
   
• Fridge#5.This cryostat is our most advanced fully-functional nuclear cooling facility. The dilution refrigerator cools to a record-low 1.75 mK. The machine has achieved lattice temperatures in copper of ~5 mK. Using Lancaster-style nuclear cooling stages, it cools superfluid ³He to record low temperatures below 100 mK. It has been used for various measurements on dirty superfluid ³He in aerogel, including the low temperature phase diagram, gapless superfluid properties and textures. In this machine quantum turbulence in superfluid ³He-B was first discovered. Recent work uses an array of quasiparticle detectors to make real-time images of quasiparticles beams and quantum turbulence generated from a vibrating wire. It has also been used for low temperature studies of solid ⁴He and spin ice materials. This machine has a very large experimental region and a large number of electrical leads to allow many parallel experiments on different samples and devices.
   
• Fridge#6.Currently being commissioned, this is the newest of the Lancaster custom made dilution refrigerators. It is expected to achieve a base temperature below 2 mK. The machine will ultimately include a double demagnetization platform to enable access to sub-millikelvin temperature measurements on quantum structures.

Personal Contact:

Feel free to discuss questions concerning possible experiments and site-relates questions directly to our Transnational Access Responsible: Viktor Tsepelin