Grant: Research Tools and Instruments - Category 1 (<$150,000)

The Hayden and Sonier groups at Simon Fraser University use magnetic resonance techniques as a sensitive probe of condensed matter systems. The research program is very broad, ranging from precise tests of fundamental symmetries in nature, to probes of magnetism at surfaces. The Hayden group has recently made advances in the new area of "spin turbulence", showing that in some circumstances the chaotic motion of nuclear spins can be reversed. This has enormous potential for future research, not least because it will lead to improvements in the resolution of state-of-the-art commercial magnetic resonance spectrometers. The Sonier group, in collaboration with Hayden, have developed an extensive set of tools for carrying out surface-sensitive magnetic resonance experiments, that will have important applications in materials science. All these experiments take place at low temperatures and have in common the need for liquid helium as a refrigerant. However, liquid helium is a non-renewable resource and is expensive, costing approximately $11 per litre. The equipment requested in this application is a small-scale, portable helium liquefier, based on the proven principle of pulse-tube refrigeration. This instrument will be capable of liquefying more than 18 liquid litres of helium per day, enough to operate two high-field magnetic resonance spectrometers, with capacity for an additional cryostat that will be used to study spin turbulence. One liquefier has the capacity to reduce operating expenses by over $70,000 per year, enabling experiments to run year round, to be used by more graduate students, and to carry out a much larger volume of research. As demand for liquid helium by individual research groups tends to fluctuate with time, the liquefier will be shared with other researchers at SFU based on need. It is hoped that eventually the department will install several of these machines, to create a bank of liquefying capacity that can meet peak demands, and make low-temperature experiments accessible to more users. For the scale of research in a typical Physics department, pulse-tube liquefiers represent a more cost-effective approach than setting up a large-scale helium liquefier, which typically costs ~$750k.