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  • 1
    Electronic Resource
    Electronic Resource
    Cryogenics, Helium Three (1964)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 15 (1964), S. 83-108 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pc.15.100164.000503
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  • 2
    Electronic Resource
    Electronic Resource
    Measurements of the Kapitza resistance and Onsager cross-coefficient for the4He crystal-superfluid interface (1983)
    Springer
    Journal of low temperature physics 51 (1983), S. 489-504 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of a heat current across the atomically rough crystal-superfluid interface in4He has been studied below 1 K. The chemical potential difference Δμ and temperature difference ΔT were measured simultaneously, the ΔT by means of a “superfluid melting-curve thermometer.” The results give the mean phonon transmission coefficient across the interface $$\bar \tau $$ and a dimensionless quantity β that determines the Onsager coefficient linking Δμ with the heat current. The transmission probability $$\bar \tau $$ is proportional toT 2 below 0.2 K, in agreement with other experiments and with various theories, and it depends slightly on the crystal orientation, increasing near thec axis. The coefficient β, which is roughly independent of temperature and orientation, agrees with a recent theory of Bowley and Edwards.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683225
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  • 3
    Electronic Resource
    Electronic Resource
    Erratum: Collisionless spin waves in normal and superfluid3He (1987)
    Springer
    Journal of low temperature physics 66 (1987), S. 127-127 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681472
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  • 4
    Electronic Resource
    Electronic Resource
    NMR in pure3He films on a Nuclepore substrate (1988)
    Springer
    Journal of low temperature physics 72 (1988), S. 213-239 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The properties of3He films on a Nuclepore substrate have been measured by pulsed NMR at a Larmor frequency of 10 MHz between 1.3 and 4.2 K. The3He film thickness was varied from 0.14 to 2 layers. The spin-spin relaxation timeT 2 agrees well with previous measurements of3He films on Mylar and Vycor glass at low temperatures. The spin-lattice relaxation timeT 1 for submonolayer films shows a strong temperature dependence consistent with a thermally activated process. This behavior has not previously been observed on amorphous substrates. The spin diffusion coefficient was measured for the thickest films at 4.2 and 2.6 K and found to be consistent with free atom motion of the3He in the vapor. In thin films or at low temperatures, the diffusion was too small to be observed. The magnetic coupling between the3He nuclei in a film and the protons in the Nuclepore substrate was determined from the effect of the3He on the proton-lattice relaxation time. It is about 100 times weaker than the interaction between3He and the fluorine nuclei in a Teflon substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682097
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  • 5
    Electronic Resource
    Electronic Resource
    Heat conduction by liquid helium II in capillary tubes. IV. Mutual friction under pressure (1981)
    Springer
    Journal of low temperature physics 43 (1981), S. 327-339 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report measurements of supercritical heat conduction in liquid helium II at pressures above the vapor pressure. The measurements were made in glass capillary tubes of diameter 50.5 and 366.8 Μm in the temperature range from 1.2 to 2.1 K. As in our previous results at the vapor pressure, a clear distinction can be made between two regimes in which the average separation of vortex lines is either comparable with or larger than the size of the flow channel. In the wider tube, at high relative velocities v between the superfluid and normal component, where the vortex spacing is small, a modified form of Gorter-Mellink mutual friction F sn is observed which varies as Fsn=Aρsρnv(v−v0)2. The coefficient A increases with pressure, and its variation with T/Tλ(p) is in fairly good agreement with Schwarz ' microscopic theory of superfluid turbulence. However, the absolute magnitude of A is in general larger than in Schwarz ' theory and also larger than most other experimental values. In the narrower tube the measurements are all in the regime where the vortex spacing is comparable with the tube size, and they do not agree with the predictions of the Gorter-Mellink law. At present, the data cannot be analyzed quantitatively in the terms of the vortex line density, because B, the vortex line scattering coefficient, is not known at high pressures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00116158
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  • 6
    Electronic Resource
    Electronic Resource
    The velocity of second sound in dilute3He-4He solutions below 0.6°K (1970)
    Springer
    Journal of low temperature physics 3 (1970), S. 619-634 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The velocity of second soundu 2 in dilute solutions of3He in4He has been measured by a pulse, time-of-flight technique using a new type of mechanical transducer. Tables of measured values ofu 2 as a function of temperature between 0.03 and 0.6° K are presented for3He concentrations in the range 0.14–6.3% at the saturated vapor pressure and under hydrostatic pressures of 10 and 20 atm. Estimates of the upper limit of the intrinsic attenuation of second sound have also been made and these are consistent with theory provided that the experimental values of the phonon thermal conductivity lifetime are used in place of the values calculated by Baym and Ebner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00628338
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  • 7
    Electronic Resource
    Electronic Resource
    Collisionless spin waves in normal and superfluid3He (1986)
    Springer
    Journal of low temperature physics 63 (1986), S. 369-399 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Standing spin-wave modes in liquid3He have been studied by cw NMR at Larmor frequencies of 1, 2, and 4 MHz and pressures of 0, 6.3, and 12.3 bar. The spin waves, which produce peaks in the NMR line, are visible at temperatures below 5 mK at zero pressure. With the assumption of a slightly simplified sample shape and no transverse spin relaxation at the walls, the theory of Leggett fits the spin-wave frequencies in the normal liquid very well, giving a value of the Fermi liquid parameterF 1 a =−0.6±0.2 at zero pressure. The width of some of the peaks is larger than expected from other determinations of the quasiparticle diffusion time τ D . This could be due to wall relaxation or to deviations from the assumed sample geometry. In the superfluid A1 and A phases, where the data cannot be fitted to existing theories, the spin-wave modes are shifted in frequency and suffer additional damping as the temperature is decreased. At still lower temperatures in the B phase an inversion of the spin-wave spectrum from one side of the NMR line to the other is observed, agreeing quantitatively with the predictions of the 1975 theory of Combescot.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681488
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  • 8
    Electronic Resource
    Electronic Resource
    The Effective Mass and Binding Energy of 4He in 3He in the Fermi Liquid Region (1998)
    Springer
    Journal of low temperature physics 113 (1998), S. 987-992 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured the solubility of 4 He in liquid 3 He down to about 40 mK and at pressures from zero up to ∼ 24 atm. The solubility was obtained from the thickness of the superfluid film in contact with unsaturated solutions of 4 He in 3 He as a function of temperature. By fitting the solubility data to Fermi liquid theory, we obtained the parameters m 4 * and Δ as a function of pressure. Here, m 4 * is the effective mass of 4 He in liquid 3 He and Δ the difference in binding energy between 4 He in pure 4 He and 4 He in liquid 3He. This difference has a minimum near 10 atm. The average of the results for m 4 * , at different pressures, is (1.3 ± 0.2)m 4. This agrees with the many body calculations of de Saavedra et al., and with the Stokes hydrodynamic mass using the partial volume of 4 He in 3 He, v 4 * . The partial volume was obtained by taking the derivative of Δ with respect to pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022544015141
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  • 9
    Electronic Resource
    Electronic Resource
    A Scaling Calculation of the Scattering of 4He Atomic Beams (1999)
    Springer
    Journal of low temperature physics 116 (1999), S. 99-132 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a simulation of the scattering in beams of helium atoms. The number of atoms N in the beams is reduced by a large scaling factor λ while the collision cross-section is increased by λ. This leaves the rate of scattering for each particle unchanged. As an example, we predict the outcome of a low temperature atomic beam experiment to measure the 4 He- 4 He atomic scattering cross-section σ at low energies. Because of the existence of a very weakly bound dimer, the low energy cross-section is expected to be unusually large, ∼1.83 × 10 5 Å 2 . In the simulation N/λ is small enough for the trajectories of all the scaled atoms to be calculated numerically. The simulation shows that the experiment is quite practicable. The proposed apparatus is just over 20 cm long, and a few centimeters wide, small enough to fit in a dilution refrigerator. The heaters and bolometers are assumed to be similar to those used in previous low temperature scattering experiments. We show that, using low intensity beams, the cross-section can be measured as a function of the relative velocity v r between ∼2 and ∼8 m/sec, corresponding to relative energies between ∼1 and ∼16 mK. By fitting σ(v r) one can determine the scattering length and effective range of the interaction. We predict that, at high intensity where multiple scattering is very important, the two beams coalesce into one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021831027102
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  • 10
    Electronic Resource
    Electronic Resource
    An experiment to measure the diffusion of4He in4He in the Fermi liquid region (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 167-175 
    Details
    ISSN: 1573-7357
    Keywords: 67.60.Dm ; 51.10.+y ; 67.55.Lf ; 67.55.Hc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The diffusion coefficient D and the thermal diffusion factor γT, for4He in liquid3He at low temperatures T, have recently been calculated by solving the Boltzmann equation derived from Fermi-liquid theory. As T → 0, γT approaches a constant and D varies as 1/T. Both transport coefficients are determined solely by a 0 34 , the l = 0 forward scattering amplitude. Because a 0 34 can be found from thermodynamic data, e.g. the solubility of4He in liquid3He, X 4 sat , a strict test of the theory is possible. We have built an apparatus to measure D and X 4 sat as functions of pressure and temperature. The ratio of the capacitances of two parallel plate capacitors measures the number of4He atoms diffusing out of the liquid into the superfluid film. A bellows initiates the diffusion by changing the pressure in the liquid and thus the equilibrium concentration. A change of ∼ 10−8 in the4He concentration can be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754573
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