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New methods for nuclear cooling into the microkelvin regime

Research paper by D. I. Bradley, A. M. Guénault, V. Keith, C. J. Kennedy, I. E. Miller, S. G. Mussett, G. R. Pickett, W. P. Pratt

Indexed on: 01 Nov '84Published on: 01 Nov '84Published in: Journal of low temperature physics



Abstract

We describe the philosophy and practice of a new method of nuclear cooling in which the copper refrigerant is immersed directly in the3He sample to be cooled using a guard cell configuration. The method has been used to cool liquid3He to ∼120 µK. We also describe a variant of the method intended for cooling metallic samples, by which a platinum NMR thermometer has been cooled to ∼13 µK. Finally, in an appendix we suggest a very simple nuclear cooling method utilizing the copper flakes used in the manufacture of paint, which will cool liquid3He to around 1 mK with a minimum of cryogenic effort.