72,815 research outputs found

    Left-Right Asymmetry of Weak Interaction Mass of Polarized Fermions in Flight

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    The left-right polarization-dependent asymmetry of the weak interaction mass is investigated. Based on the Standard Model, the calculation shows that the weak interaction mass of left-handed polarized fermions is always greater than that of right-handed polarized fermions in flight with the same velocity in any inertial frame. The asymmetry of the weak interaction mass might be very important to the investigation of neutrino mass and would have an important significance for understanding the parity nonconservation in weak interactions.Comment: 8 pages, 2 figures, corrected calculatio

    Superconducting properties of Gd-Ba-Cu-O single grains processed from a new, Ba-rich precursor compound

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    Gd-Ba-Cu-O (GdBCO) single grains have been previously melt-processed successfully in air using a generic Mg-Nd-Ba-Cu-O (Mg-NdBCO) seed crystal. Previous research has revealed that the addition of a small amount of BaO2 to the precursor powders prior to melt processing can suppress the formation of Gd/Ba solid solution, and lead to a significant improvement in superconducting properties of the single grains. Research into the effects of a higher Ba content on single grain growth, however, has been limited by the relatively small grain size in the earlier studies. This has been addressed by developing Ba-rich precursor compounds Gd-163 and Gd-143, fabricated specifically to enable the presence of greater concentrations of Ba during the melt process. In this study, we propose a new processing route for the fabrication of high performance GdBCO single grain bulk superconductors in air by enriching the precursor powder with these new Ba rich compounds. The influence of the addition of the new compounds on the microstructures and superconducting properties of GdBCO single grains is reported

    Homogeneous nucleation in spatially inhomogeneous systems

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    Homogeneous nucleation of a vapor in the presence of the loss of clusters by diffusion and thermophoretic drift is investigated. Analytical results are obtained for the cluster size distribution and the rate of nucleation by solving the modified kinetic equation for nucleation. The implications of cluster loss by diffusion and phoretic drift on the onset of the homogeneous nucleation of silicon vapor in the horizontal epitaxial chemical vapor deposition reactor is discussed. The range of conditions under which the loss of subcritical clusters by diffusion and drift becomes important for the interpretation of diffusion cloud chamber experimental data of the onset conditions of the homogeneous nucleation of vapors is also delineated