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Title: Dry demagnetization cryostat for sub-millikelvin helium experiments: Refrigeration and thermometry

We demonstrate successful “dry” refrigeration of quantum fluids down to T = 0.16 mK by using copper nuclear demagnetization stage that is pre-cooled by a pulse-tube-based dilution refrigerator. This type of refrigeration delivers a flexible and simple sub-mK solution to a variety of needs including experiments with superfluid {sup 3}He. Our central design principle was to eliminate relative vibrations between the high-field magnet and the nuclear refrigeration stage, which resulted in the minimum heat leak of Q = 4.4 nW obtained in field of 35 mT. For thermometry, we employed a quartz tuning fork immersed into liquid {sup 3}He. We show that the fork oscillator can be considered as self-calibrating in superfluid {sup 3}He at the crossover point from hydrodynamic into ballistic quasiparticle regime.
Authors:
; ; ;  [1] ;  [2]
  1. Low Temperature Laboratory, O.V. Lounasmaa Laboratory, Aalto University, FI-00076 AALTO (Finland)
  2. BlueFors Cryogenics Ltd, Arinatie 10, 00370 Helsinki (Finland)
Publication Date:
OSTI Identifier:
22327830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; COPPER; DEMAGNETIZATION; EQUIPMENT; HELIUM 3; QUARTZ; REFRIGERATION; SUPERFLUIDITY