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.     

On solving systems of ordinary differential equations on MIMD-computers

The error of solution of Cauchy problems for systems of ordinary differential equations is estimated in the case where the input data are approximate. It is shown how to prepare a program for computing the right-hand sides of the system automatically and simultaneously. Diagrams are presented to illustrate the efficiency of parallelization. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 175–182, March–April 2007.     

Spin–Lattice Relaxation of Mn Ions in Nanostructures with Semiconductor Quantum Dots

We use the combination of nonequilibrium phonon and exciton luminescence techniques to study the spin dynamics in diluted magnetic semiconductor structures with (Cd,Mn)Te and (Cd,Mn)Se quantum dots (QDs). We show that the spin–lattice relaxation (SLR) of Mn ions in these structures differs strongly from the SLR in quantum wells. We explain the results by a model where SLR process in structures with QDs is modified by the spin diffusion on Mn ions from the QD to a wetting layer.     

Local laser-induced change of optical properties in the bulk of photochromic porous silicate glass doped by silver and copper halides

The principles of the formation of modified areas of a spherical shape and complex structure in porous glass plates doped by silver and copper halides under the continuous radiation of a fiber laser focused inside the plate have been formulated. The results of the study of the obtained modified areas are given.     

Analysis of the operation of charging units of supercapacitor starters of automobile motors

It is suggested to use supercapacitor starters that simplify automobile motor cranking in cold weather. Transitive processes that take place in charging units of fly back and fly forward transducers have been analyzed.     

Morphology of craters at hypervelocity impact in isotropic composites with inclusions

Results of a study of hypervelocity impact in model disperse-reinforced composites with an epoxy or aluminum matrix with metallic (Al and Pb) or ceramic (SiO₂) inclusions are reported. The goal of the present study is to find materials that possess a higher resistance to penetration of a high-velocity projectile compared with materials of separate components. This resistance is characterized by the ratio of the depth of a crater in a sufficiently thick target to the diameter of a spherical projectile. For two composites studied, we show that in impact of a steel particle with a velocity ranging from3 to11km/sec, the crater depth is approximately one projectile diameter smaller than that for lead or aluminum targets. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 3, pp. 139–151, May–June, 1997.