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Non linear damping by ballistic quasiparticles in superfluid '3HE-#beta#Carney, John Paul January 1989 (has links)
No description available.
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Experiments on a dilute '3He-'4He solution in a large magnetic field gradientJackson, Douglas Anthony January 1993 (has links)
No description available.
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An experimental investigation into the electrical transport properties of Laâ†2CuOâ†4â†+â†#delta# and Ndâ†2CuOâ†4â†+â†#delta#Ryder, J. January 1990 (has links)
No description available.
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Use of '1'9F NMR thermometry in the investigation of magnetic textures in superfluid '3He-AMossavati, Ruzbeh January 1988 (has links)
No description available.
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Properties of '3He-'4He mixturesChurch, Rosemary Jane January 1989 (has links)
No description available.
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A PrNiâ†5 refrigerator developed for nuclear orientation below 1mKWhite, Jeremy Philip January 1991 (has links)
No description available.
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An NMR study of adsorbed helium filmsKent, Anthony Joseph January 1985 (has links)
The properties of sub-monolayer Helium-3 films adsorbed on two totally different but planar substrates, Mylar<sup>†</sup> film and exfoliated graphite have been studied using NMR. The nuclear magnetic relaxation times T<sub>1</sub> and T<sub> 2</sub> have been measured as functions of fractional monolayer completion, temperature, substrate plane orientation and Larmor frequency using a specially designed and constructed NMR spectrometer system. The results obtained with a Mylar film substrate are consistent3with the formation of patches of solid <sup>3</sup>He at regions of preferential adsorption on the substrate. Measurements of T<sub>2</sub> m very low coverage <sup>3</sup>He films on exfoliated graphite also indicate that the adsorbate forms areas of relatively high density solid, in agreement with the thermodynamic analysis of Elgin and Goodstein. Finally, detailed measurements of T<sub>2</sub> as a function of all of the above parameters at low areal densities will help us to characterise the relaxation processes for the fluid phase of <sup>3</sup><sup>3</sup>He on exfoliated graphite. <sup>†</sup>Mylar is the tradename of poly(ethelene-terephthalate) film, marketed by Du Pont.
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Experiments on polarized and unpolarized dilute '3He-'4He solutionsNichols, Timothy Robert January 1989 (has links)
No description available.
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Trapped positrons for high-precision magnetic moment measurementsHoogerheide, Shannon Michelle Fogwell 09 August 2013 (has links)
<p> A single electron in a quantum cyclotron provides the most precise measurement of the electron magnetic moment, given in units of the Bohr magneton by <i> g</i>/2 = 1.001 159 652 180 73 (28) [0.28 ppt]. The most precise determination of the fine structure constant comes from combining this measurement with Standard Model theory, yielding α<sup>-1</sup> = 137.035 999 173 (34) [0.25 ppb], limited by the experimental uncertainty of the electron <i> g</i>-value. The most stringent test of CPT symmetry in leptons comes from comparing the electron and positron magnetic moments, limited by the positron uncertainty at 4.2 ppt. A new high-stability apparatus has been built and commissioned for improved measurements of the electron and positron magnetic moments, a greatly improved test of lepton CPT symmetry, and an improved determination of the fine structure constant. These new measurements require robust positron loading from a retractable radioactive source that is small enough to avoid compromising the high-precision environment of our experiment. The design and implementation of such a scheme is a central focus of this work. Robust positron loading at a rate of 1-2 e<sup>+</sup>/min from a 6.5 μCi <sup> 22</sup>Na source has been demonstrated.</p>
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A transition-edge-sensor-based instrument for the measurement of individual He2* excimers in a superfluid 4He bath at 100 mKCarter, Faustin Wirkus 17 February 2016 (has links)
<p> This dissertation is an account of the first calorimetric detection of individual He*<sub>2</sub> excimers within a bath of superfluid <sup>4</sup>He. When superfluid helium is subject to ionizing radiation, diatomic He molecules are created in both the singlet and triplet states. The singlet He molecules decay within nanoseconds, but due to a forbidden spin-flip the triplet molecules have a relatively long lifetime of 13 seconds in superfluid He. When He*<sub> 2</sub> molecules decay, they emit a ~15 eV photon. Nearly all matter is opaque to these vacuum-UV photons, although they do propagate through liquid helium. The triplet state excimers propagate ballistically through the superfluid until they quench upon a surface; this process deposits a large amount of energy into the surface. The prospect of detecting both excimer states is the motivation for building a detector immersed directly in the superfluid bath.</p><p> The detector used in this work is a single superconducting titanium transition edge sensor (TES). The TES is mounted inside a hermetically sealed chamber at the baseplate of a dilution refrigerator. The chamber contains superfluid helium at 100 mK. Excimers are created during the relaxation of high-energy electrons, which are introduced into the superfluid bath either in situ via a sharp tungsten tip held above the field-emission voltage, or by using an external gamma-ray source to ionize He atoms. These excimers either propagate through the LHe bath and quench on a surface, or decay and emit vacuum-ultraviolet photons that can be collected by the detector.</p><p> This dissertation discusses the design, construction, and calibration of the TES-based excimer detecting instrument. It also presents the first spectra resulting from the direct detection of individual singlet and triplet helium excimers.</p>
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