Production of Neptunium and Plutonium Tracers in Nuclear Reactions of 236U with 21-to-60-MeV 3He Ions1

Production of ²³⁶Pu, ²³⁷Pu, and ²³⁵Np by the reactions ²³⁶U(³He,t^-)²³⁶Pu, ²³⁶U(³He,2n)²³⁷Pu, and ²³⁶U(³He,p3n)²³⁵Np with 43- and 60-MeV ³He ion beams on the K-130 cyclotron of the University of Jyvüaskylüa was studied. The cross sections for the reactions were determined. The curves of yields with thick targets were derived from the cross sections. The results are discussed and compared with previous data on the other reactions yielding the same final products.     

Measuring Deep Metastability and Its Effect on Synchronizer Performance

Present measurement techniques do not allow synchronizer reliability to be measured in the region of most interest, that is, beyond the first half cycle of the synchronizer clock. We describe methods of extending the measurement range, in which the number of metastable events generated is increased by four orders of magnitude and events with long metastable times are selected from the large number of more normal events. The relationship found between input times and the resulting output times is dependent on accurate measurement of input time distributions with deviations of less than 10 ps. We show how the distribution of to clock times at the input can be characterized in the presence of noise and how predictions of failure rates for long synchronizer times can be made. Anomalies such as the increased failure rates in a master-slave synchronizer produced by the back edge of the clock are explained and demonstrated.     

CAD of efficient TMmn0 single-mode elliptical applicators with coaxial excitation.

This paper suggests computational and engineering approaches to designing single-mode elliptical applicators for thermal processing of cylindrical samples of relatively small diameters. Through a systematic computational experimentation employing a 3D conformal FDTD model, we show that stable and efficient excitation of even and odd TMo modes of elliptical waveguides can be achieved by appropriate placing of two (one active and one passive) coaxial probes extended in the longitudinal direction of the cavity of relatively small height and by choosing the dimensions of the cavity. Effects produced by cylindrical loads inserted in the electric field maxima of the applicators featuring even TM010, TM110, and TM210 modes are studied for materials with different dielectric constants and the loss factors. It is shown that with the proposed excitation supported by simulation of energy coupling and dissipated power the elliptical structure is capable of operating any of these modes in a single-mode regime and generating satisfactory uniformity of the dissipated power within the cylindrical samples.     

The avalanche ionization rate in argon and krypton measured at the shockwave Mach numbers close to the flow instability development threshold

The ionization rates of argon and krypton were measured in a relaxation zone behind the shockwave front for the Mach numbers corresponding to stable flow regimes close to the threshold for development of the flow instability of types I and II. The experimental rates of the avalanche ionization exceed theoretical predictions. It is suggested that the discrepancy is related to the existence of an additional channel for the energy transfer between particles.     

Ultimate InAsSbP solid solutions for 2.6–2.8-μm LEDs

Epitaxial layers of phosphorus-rich InAs_1? y ? x Sb _y P _x solid solutions were obtained by liquid phase epitaxy (LPE). The films with x=0.32 were grown at 575 °C on isoperiodic (100)InAs substrates. It is shown that the growth of InAsSbP layers from a phosphorus-rich liquid phase is accompanied by saturation of the phosphorus content in the solid state. InAsSbP-based diode heterostructures emitting in the 2.6–2.8 μ m wavelength range were obtained, the output emission power of which is sufficient for detecting both natural and industrial gases in the atmosphere.     

Neural network optimization of complex microwave structures with a reduced number of full‐wave analyses

An innovative technique of neural network optimization of substantially less computational cost is presented as a procedure suitable for viable computer‐aided design of complex microwave systems. The number of necessary full‐wave simulations in this optimization procedure is dramatically reduced because of a special objective function (OF) and constrained optimization response surface (CORS) sampling in the dynamic training of the decomposed radial‐basis‐function network. A high rate of convergence to an optimization objective is shown to be dependent on the combined effect of the OF and CORS technique. Performance of the algorithm is illustrated by its application to a waveguide band‐pass filter, a loaded microwave oven, and a dielectric resonator antenna; their optimal designs are found from five‐parameter optimizations requiring as little as 167, 177, and 99 analyses, respectively. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.