265 research outputs found
Power spectral measurements of clear-air turbulence to long wavelengths for altitudes up to 14,000 meters
Measurements of three components of clear air atmospheric turbulence were made with an airplane incorporating a special instrumentation system to provide accurate data resolution to wavelengths of approximately 12,500 m (40,000 ft). Flight samplings covered an altitude range from approximately 500 to 14,000 m (1500 to 46,000 ft) in various meteorological conditions. Individual autocorrelation functions and power spectra for the three turbulence components from 43 data runs taken primarily from mountain wave and jet stream encounters are presented. The flight location (Eastern or Western United States), date, time, run length, intensity level (standard deviation), and values of statistical degrees of freedom for each run are provided in tabular form. The data presented should provide adequate information for detailed meteorological correlations. Some time histories which contain predominant low frequency wave motion are also presented
Tricritical Point and the Doping Dependence of the Order of the Ferromagnetic Phase Transition of La1-xCaxMnO3
We report the doping dependence of the order of the ferromagnetic metal to
paramagnetic insulator phase transition in La1-xCaxMnO3. At x = 0.33,
magnetization and specific heat data show a first order transition, with an
entropy change (2.3 J/molK) accounted for by both volume expansion and the
discontinuity of M ~ 1.7 Bohr magnetons via the Clausius-Clapeyron equation. At
x = 0.4, the data show a continuous transition with tricritical point exponents
alpha = 0.48+/- 0.06, beta = 0.25+/- 0.03, gamma = 1.03+/- 0.05, and delta =
5.0 +/- 0.8. This tricritical point separates first order (x<0.4) from second
order (x>0.4) transitions.Comment: 14 pages, including 4 figures: i.e. 10 pages of text and 4 pages of
figures. to appear in Physical Review Letters (accepted
Magnetic fluctuations in frustrated Laves hydrides R(Mn_{1-x}Al_{x})_{2}H_{y}
By neutron scattering, we have studied the spin correlations and spin
fluctuations in frustrated Laves hydrides, where magnetic disorder sets in the
topologically frustrated Mn lattice. Below the transition towards short range
magnetic order, static spin clusters coexist with fluctuating and alsmost
uncorrelated spins. The magnetic response shows a complexe lineshape, connected
with the presence of the magnetic inhomogeneities. Its analysis shows the
existence of two different processes, relaxation and local excitations, for the
spin fluctuations below the transition. The paramagnetic fluctuations are
discussed in comparison with classical spin glasses, cluster glasses, and non
Fermi liquid itinerant magnets
Signal yields, energy resolution, and recombination fluctuations in liquid xenon
This work presents an analysis of monoenergetic electronic recoil peaks in
the dark-matter-search and calibration data from the first underground science
run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and
light yields for electronic recoil energies between 5.2 and 661.7 keV are
measured, as well as the energy resolution for the LUX detector at those same
energies. Additionally, there is an interpretation of existing measurements and
descriptions of electron-ion recombination fluctuations in liquid xenon as
limiting cases of a more general liquid xenon re- combination fluctuation
model. Measurements of the standard deviation of these fluctuations at
monoenergetic electronic recoil peaks exhibit a linear dependence on the number
of ions for energy deposits up to 661.7 keV, consistent with previous LUX
measurements between 2-16 keV with H. We highlight similarities in liquid
xenon recombination for electronic and nuclear recoils with a comparison of
recombination fluctuations measured with low-energy calibration data.Comment: 11 pages, 12 figures, 3 table
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