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We present a lattice model that illustrates avalanche flow ina driven, disordered system. Structural disorder is associatedwith rectangular grains that have orientational degrees of freedom.Grain orientation transitions couple the evolving disorder withsurface instabilities. The simulated event size distributionhas features in common with observed surface granular flow and,in contrast to previous sandpile models, does not have a simplescaling behaviour. We have identified properties of the sandpilesurface that correlate with the internal structural disorder.The simulation results support a model of granular dynamicsin which surface flow and granular relaxation processes arestrongly coupled. 相似文献
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Gorham PW Barwick SW Beatty JJ Besson DZ Binns WR Chen C Chen P Clem JM Connolly A Dowkontt PF DuVernois MA Field RC Goldstein D Goodhue A Hast C Hebert CL Hoover S Israel MH Kowalski J Learned JG Liewer KM Link JT Lusczek E Matsuno S Mercurio B Miki C Miocinović P Nam J Naudet CJ Ng J Nichol R Palladino K Reil K Romero-Wolf A Rosen M Ruckman L Saltzberg D Seckel D Varner GS Walz D Wu F;ANITA Collaboration 《Physical review letters》2007,99(17):171101
We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation of the Askaryan effect in ice. As part of the complete validation process for the ANITA experiment, we performed an experiment at the Stanford Linear Accelerator Center in June 2006 using a 7.5 metric ton ice target. We measure for the first time the large-scale angular dependence of the radiation pattern, a major factor in determining the solid-angle acceptance of ultrahigh-energy neutrino detectors. 相似文献
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CARBOXYLATED ZINC-PHTHALOCYANINE, INFLUENCE OF DIMERIZATION ON THE SPECTROSCOPIC PROPERTIES. AN ABSORPTION, EMISSION, AND THERMAL LENSING STUDY 总被引:1,自引:0,他引:1
R. MARTíN NEGRI ANITA ZALTS ENRIQUE A. SAN ROMáN PEDRO F. ARAMENDíA SILVIA E. BRASLAVSKY 《Photochemistry and photobiology》1991,53(3):317-322
Monomer and dimer absorption and emission spectra, and dimerization constants are reported for the diamide of the zinc-tetracarboxyphthalocyanine in pure dimethylformamide (DMF) and in H2O/DMF mixtures at room temperature. The dimerization constant increases steadily with the water content. The monomer absorption Q-band is insensitive to the solvent composition, whereas dimer spectra show great variations with the water content. Stationary emission measurements show that fluorescence originates exclusively from the monomers. The fluorescence spectrum as well as its absolute fluorescence quantum yield, measured by steady-state thermal lensing, are also insensitive to the solvent composition. The thermal lensing method is discussed for the case of two absorbing species in equilibrium. 相似文献
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The Eu ions confined in an RF quadrupole trap, has been optically detected. Using a tunable dye laser which is pumped by a
Nd-YAG pulsed laser system, the resonance 9S4^9S_4–6p
3/2, J = 5 transition of the Eu ions have been excited and the resulting fluorescence to the metastable 9D4-6^9D_{4-6} state has been detected. In preparation to determine the ground-state hyperfine splitting of the odd isotopes we found the
optimum trapping operating point. We have also observed a number of instabilities inside the region of the stability for an
ideal trap. These non-linear resonances arise from higher-order contributions to the ideal quadrupole potential. 相似文献
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