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  • 1
    Electronic Resource
    Electronic Resource
    Reusable pressure seal for low temperature use requiring a small annular space (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3621-3622 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A reusable, low-temperature, super leaktight joint sealed with epoxy is presented which increases the available working area over that provided by a coventional bolted O-ring system. The seal is usable at arbitrarily low temperatures and was tested with a pressure of 70 bar with no apparent deterioration in performance. The simple method of assembly and disassembly is described and the results of various tests are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141530
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical Oscillations in Conducting Polymers (1998)
    Springer
    Journal of low temperature physics 113 (1998), S. 1129-1134 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During studies of magnetoresistance of disordered systems composed of CSA-doped PPy or PANI in PMMA, striking periodic pulses in potential were detected which changed nature depending on temperature, magnetic field, applied current, and fabrication process. Extensive measurements show some more new features. The transition from regular pulsing to chaos is clearly seen, and may be controlled in a given sample by bias current, temperature and/or applied magnetic field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022541409206
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  • 3
    Electronic Resource
    Electronic Resource
    Coupling of the Nuclear Spin Alignment of Quadrupolar Nuclei to 3He at Interfaces (1998)
    Springer
    Journal of low temperature physics 113 (1998), S. 323-328 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the relaxation of nuclear spin alignments have been carried out using NQR spin echo studies of powdered antimony in contact with liquid 3 He. This system differs from previous studies of the relaxation and magnetization coupling of 3 He at surfaces because the magnetizations 〈 S z 〉≃ 0. The spin alignments 〈 S z 2 〉 are the relevant dynamical variables. The analysis of the experimental results shows that the coupling of the nuclear spin alignment of the antimony nuclei to the magnetization of the 3 He nuclei is determined by the spectral density of the fluctuations of the spin-spin dipolar couplings at the interface. This power density is attributed to the zero-point motions (atom-atom and atom-vacancy exchange) of the 3 He atoms on the surface of the metal particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022558919066
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  • 4
    Electronic Resource
    Electronic Resource
    Broadband Frequency Study of the Zero Sound Attenuation Near the Quantum Limit in Normal Liquid 3He Close to the Superfluid Transition (1998)
    Springer
    Journal of low temperature physics 113 (1998), S. 543-548 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The zero sound attenuation, α0(ω,T, P), of normal liquid 3 He has been studied over a broad range of frequency (ω/2π = 8 – 50 MHz). Data has been collected at a constant temperature (T ≈ 1.1 mK) which is just above the superfluid transition temperature, T c , when the liquid is near a pressure, P, of 1 bar. The results are compared to Landau's prediction in the quantum limit, k B T ≪ ħω ≪ k B T F , where α0(ω,T,P) = α′(P) T 2[l + (ħω/2πk B T)2]. Deviations from Landau's prediction are compared to the results of other workers and are discussed with respect to additional (unidentified) extrinsic background effects and (possible) intrinsic scattering mechanisms due to fluctuations in the liquid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022576817674
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  • 5
    Electronic Resource
    Electronic Resource
    Conducting polymers at low temperatures and high magnetic fields (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 605-610 
    Details
    ISSN: 1573-7357
    Keywords: 72.15. Jf ; 71.20.Hk ; 71.55.Jv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Advances in the synthesis of organic conducting polymer systems has increased the electrical conductivity of these systems by several orders of magnitude in the last decade. Several practical applications are envisioned for such systems, but a thorough understanding of the conduction mechanisms and identification of the charge carriers is lacking, making design and implementation for bulk synthesis difficult. In order to clarify our understanding of the electrical properties of these systems, the resistivity and magnetoresistivity of various polymers doped near the metal - insulator transition, such as polyaniline protonated by camphor sulfonic acid (PANi-CSA) and polypyrrole doped with PF6 (PPy-PF6), have been studied down to 25 mK in magnetic fields up to 16 T.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753361
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  • 6
    Electronic Resource
    Electronic Resource
    Nuclear spin-lattice relaxation times of metallic antimony at low temperatures (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 611-615 
    Details
    ISSN: 1573-7357
    Keywords: 07.20 Dt ; 76.60.-k ; 72.15.Lh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have used pulsed Nuclear Quadrupole Resonance (NQR) techniques to measure the nuclear spin-lattice relaxation times in antimony at low temperatures. High quality echoes with strong signal/noise ratios were only observed for finely powdered samples of high purity (99.9999%). The samples were carefully annealed and diluted with fine silica to below the percolation limit to minimize RF heating. The powder mixture was immersed in liquid3He to ensure good thermal contact to a sintered silver heat exchanger attached to a copper nuclear demagnetization refrigerator. We report the temperature dependence of the nuclear spin-lattice relaxation times for the multiple level nuclear spin system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753362
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear Spin Relaxation of Powdered Metallic Antimony in Liquid 3He (1998)
    Springer
    Journal of low temperature physics 112 (1998), S. 21-45 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nuclear spin relaxation studies have been carried out to determine the surface relaxation of powdered Sb immersed in liquid 3 He. The surface relaxation mechanism was observed to be significantly more effective than the bulk Korringa relaxation rate for temperatures T 〈 75 mK. This surface relaxation is attributed to the modulation of the dipole-dipole interaction between the Sb spins at the metal surface and the 3 He spins in the solid-like layer on the surface by the quantum zero-point motion of these 3 He atoms. The total relaxation has been analyzed in terms of the surface relaxation and the spin diffusion through the bulk of the Sb particles. The experimental results are in excellent agreement with the theory developed for this system. Replacement of the 3 He by 4 He removes the surface relaxation component and restores the relaxation rates to the bulk value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022289811309
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  • 8
    Electronic Resource
    Electronic Resource
    Ultra-Low Temperature Thermometry Using Zeeman Perturbed NQR (1998)
    Springer
    Journal of low temperature physics 110 (1998), S. 763-778 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the results of measurements of the magnetic field perturbed nuclear quadrupole resonance (NQR) lines of powdered Sb immersed in liquid 3He at low temperatures. The magnetic field was used to separate the frequencies of the allowed transitions between the $$I_Z = \pm \frac{1}{2}$$ and $$\frac{3}{2}$$ levels that correspond to the zero field NQR absorption at 11.5289 MHz for121 Sb. The spectrum for the powder sample consists of two sharp lines with known separation. The ratios of the intensities of these two lines depends only on the difference in thermal population of the nuclear spin levels and can be used for thermometry at very low temperatures. Pulsed NQR measurements of this intensity ratio from 0.25 to 1.45 mK were in good agreement with the expected Boltzmann distributions. Temperature resolutions of 20% could be achieved for signal integration times of ∼ 1 hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022610726294
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  • 9
    Electronic Resource
    Electronic Resource
    Isochores in superfluid4He between 25 bar and the melting curve (1977)
    Springer
    Journal of low temperature physics 29 (1977), S. 445-451 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Isochores in superfluid4He between 25 bar and the melting curve have been measured to high resolution. Together with the published results of Maynard, these results provide the self-consistent basis for establishing the equation of state in the superfluid phase for temperatures above 1 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00661539
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  • 10
    Electronic Resource
    Electronic Resource
    Dissipative flow of superfluid4He through a small orifice by quantum and thermal nucleation of vortices (1992)
    Springer
    Journal of low temperature physics 89 (1992), S. 207-216 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Flow measurements in ultra-pure 4 He through a micron-size orifice at millikelvin temperatures show the transition from thermal to quantum nucleation of nanometer-size vortices below a crossover temperature of 0.147 K. Detailed analysis, similar to that done for macroscopic quantum tunnelling in superconducting junctions, yields parameters which accurately predict the mean value and the distribution width of the critical velocities at all temperatures. These observations establish the close relationship between this type of critical flow and negative ion motion in superfluid 4 He and strongly suggest that the underlying mechanism is identical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692593
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