We report muon spin relaxation and rotation measurements on sintered ceramic samples of Nd2 "Ce"Cu04y and a large single crystal of Nd2Cu04 y. We find an electronic phase diagram that is quite similar to that of hole-doped superconductors such as La2 "Sr"Cu04y although the doping of electrons into the system is less efficient in destroying the static moments on the copper ions. Static magnetic order appears in Nd2Cu04~below about 250 K; two spin reorientations are seen at T=75 and 35 K, providing information about the muon site in this material.
The paper describes an experimental study of the structure of air-water mixtures flowing vertically. Resistivity probe techniques were applied to measurements of local void properties, including void fraction, gas-phase convection velocity, bubble size distributions and space-time correlation functions. The axial development of flows for six different air-water mixing conditions were examined. Measurements up to 108 diameters from inlet indicated that, while flow patterns for the different mixers may be significantly different initially, the flows tend to develop towards a common structure determined only by the flux rates of the two phases. This was evidenced by the convergence of the void and velocity profiles, and particularly the bubble size distributions, as the flow developed. Estimates of bubble sizes for these more developed conditions, based on a balance of energy between the interfacial structure and the turbulent structure, gave values of diameters which were on average 13% above experimental values. The void distributions obtained for bubbly flow conditions, after an adequate settling length, appear to be characterized by a local minimum at the centre of the pipe.
The decay of a jet discharging from a circular nozzle parallel to and displaced from a solid surface is investigated under conditions where the transitional process from circular-jet flow to oblate wall-jet flow begins in the initial, transition or self-preserving regions of the original jet. The influence of displacement of the nozzle from the plane on the developed three-dimensional wall jet downstream is demonstrated and it is found that the transitional interaction with the plane is more extended when the plane interacts first in the initial zone of the circular jet. Measurements of turbulence and Reynolds stress show the transverse mixing parallel to the plane to exceed that perpendicular to the plane, and are generally consistent with the spreading rates in these two directions, the ratio of which approaches 8·5 at large distances from the nozzle. It is shown that the interaction between the plane and jet involves a relatively large-scale coherent motion in which components of velocity directed towards or away from the surface are associated with outflow or inflow along the surface. This motion is more extended in the direction parallel to the surface and provides a mechanism for the increases in mixing rate in the direction parallel to the plane.
A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.
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