Highly Sensitive Capacitive Pressure Gauge

Straty, G. C.; Adams, E. D.

doi:10.1063/1.1683806

Cited by 267 publications

(43 citation statements)

References 11 publications

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“…18 The melting curve thermometer was a capacitive Straty-Adams strain pressure gauge 19 with ∼5 μbar accuracy. The resonator in these cross-check experiments was a commercially available quartz tuning fork with 0.6 mm wide tines, which had exactly the same dimensions as in the present work.…”

Section: Thermometrymentioning

confidence: 99%

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

Todoshchenko

Kaikkonen

Blaauwgeers

et al. 2014

Review of Scientific Instruments

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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 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 3 He. We show that the fork oscillator can be considered as self-calibrating in superfluid 3 He at the crossover point from hydrodynamic into ballistic quasiparticle regime.

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Section: Thermometrymentioning

confidence: 99%

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

Todoshchenko

Kaikkonen

Blaauwgeers

et al. 2014

Review of Scientific Instruments

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“…A temperature gradient is present across the Vycor; the cell remains at a low temperature. The pressure of the solid is measured by capacitance strain gages [19] C1 and C2 and the pressures of the reservoirs are measured by pressure gauges P1 and P2 located outside the cryostat. Using our original apparatus [13,14], a chemical potential difference, ∆µ, could be imposed between the Vycor rods by the creation of a pressure difference ∆P = P 2 − P 1 = 0 by adding or subtracting atoms from R1 or R2 using lines 1 and 2.…”

mentioning

confidence: 99%

Observation of thermomechanical equilibration in the presence of a solidH4econduit

Ray

Hallock

2010

Phys. Rev. B

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We observe a thermo-mechanical effect when a chemical potential difference is created by a temperature difference imposed between two liquid reservoirs connected to each other through Vycor rods in series with solid hcp 4 He. By creating a temperature difference, ∆T , between the two reservoirs, we induce a rate-limited growth of a pressure difference between the two reservoirs, ∆P . In equilibrium ∆P vs.∆T is in quantitative agreement with the thermo-mechanical effect in superfluid helium. These observations confirm that below ∼ 600 mK a flux-limited flow exists through the solid helium.

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“…Before mounting in the sample cell, the samples are heated at 150 C in vacuum for 3 h at 2 Â 10 À4 Pa to remove adsorbed molecules. We have measured pressures using a Straty-Adams-type capacitive pressure gauge 13) attached to the sample cell made of BeCu. The cell contains the Gelsil disks and one side of the cell wall acts as the diaphragm of the pressure gauge.…”

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confidence: 99%

Liquid–Solid Transition and Phase Diagram of⁴He Confined in Nanoporous Glass

2008

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We have studied the liquid-solid (L-S) phase transition of 4 He confined in nanoporous Gelsil glass that has interconnected nanopores of 2.5-nm diameter. The L-S boundary is determined by a series of measurements of pressure versus temperature along isochores and the rate of temperature change during slow cooling and warming in a semi-adiabatic condition. Below 1 K, the freezing pressure is elevated by 1.2 MPa from the bulk freezing pressure, and appears to be independent of temperature. The Tindependent freezing pressure strongly suggests the existence of the localized Bose-Einstein condensation state.KEYWORDS: superfluidity, Bose-Einstein condensation, quantum phase transition, porous media DOI: 10.1143/JPSJ.77.013601Quantum phase transition (QPT) has attracted considerable attention in condensed matter physics.1) Bose systems in periodic or random potential offer a typical example of QPT.2) In ultracold atoms with periodic potential, a QPT between the superfluid and Mott insulator has been reported.3) Thin superconducting films 4) and Josephson junction arrays 5) have also been extensively studied as disordered Bose systems exhibiting QPTs.4 He in porous media is an important model system as strongly correlated Bosons in an external potential. One can freely control many properties such as the system dimensionality, topology, and disorder by changing the pore size and the pore structure. For the last three decades, a number of experimental studies have been carried out.6-10) The effects of the quenched disorder on the critical phenomena of superfluid 4 He were investigated using Aerogel. 7) In porous Vycor glass, a dilute Bose gas state was demonstrated.9) Recently, we studied the superfluid transition of 4 He confined in a nanoporous Gelsil glass of 2.5 nm pore diameter using a torsional oscillator (TO).11) The Gelsil glass has three-dimensionally interconnected nanopores and the pore structure is random. We summarize the results in Fig. 1 together with the result of the present work. The TO study revealed that superfluid transition temperature T c near 0 MPa is 1.4 K, suppressed to 2/3 of the bulk point, 2.17 K. T c decreases progressively as pressure increases and then approaches 0 K at a critical pressure P c ¼ 3:4 MPa. This is strikingly different from the behavior of bulk 4 He, namely the line, which terminates at the freezing curve. This behavior clearly shows that the confined 4 He undergoes a QPT at the quantum critical pressure P c .Our finding of the quantum critical pressure raises an interesting question. The nonsuperfluid (NSF) state may exist even at 0 K. What is the nature of the NSF state? It must be entirely different from the usual normal fluid of bulk 4 He. There should be the liquid-solid (L-S) phase transition, and the determination of the L-S boundary on the P-T phase diagram provides thermodynamic information on the NSF state. To reveal the L-S boundary, we measured pressure versus temperature PðTÞ along isochores of 4 He in Gelsil. 12)However, the temperature regulation in the PðTÞ me...

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Highly Sensitive Capacitive Pressure Gauge

Cited by 267 publications

References 11 publications

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

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

Observation of thermomechanical equilibration in the presence of a solidH4econduit

Liquid–Solid Transition and Phase Diagram of⁴He Confined in Nanoporous Glass

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Highly Sensitive Capacitive Pressure Gauge

Cited by 267 publications

References 11 publications

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

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

Observation of thermomechanical equilibration in the presence of a solidH4econduit

Liquid–Solid Transition and Phase Diagram of4He Confined in Nanoporous Glass

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Liquid–Solid Transition and Phase Diagram of⁴He Confined in Nanoporous Glass