High energy pp data and the reggeon theory of diffraction scattering

Recent proton-proton scattering experiments from the CERN ISR show several striking features. There is strong evidence that the total cross section is rising. The elastic differential cross section shows a break in the forward slope, as well as a pronounced dip-bump structure, with the dip located at t ? ? 1.3 (GeV/c)². We demonstrate that all these features and their energy dependence can be simultaneously and quantitatively very well described within the framework of Gribov reggeon calculus.     

Quasi-fission and other strongly damped collisions between 63Cu ions and 197Au nuclei

The interaction of ⁶³Cu ions with ¹⁹⁷Au nuclei have been studied experimentally at incident energies of 365 and 443 MeV (1.1 and 1.4 times the Coulomb barrier). Mass and kinetic energy distributions of reaction products have been measured at several angles. Near the grazing angle, a continuous transition was found from elastic events to partially damped (PD) events, and to fully damped events (quasi-fission, QF). Away from the grazing angle a clean separation between elastic and QF events was observed. Events that may be due to fission following fusion (CF) were also obtained. Results are discussed in terms of decomposition into PD, QF, and CF components. The QF kinetic energy is independent of the incident energy (implying full damping of the initial relative motion). It is lower than the Coulomb barrier and close to the kinetic energies from the fission of similar systems. The angular distribution is peaked somewhat forward of the grazing angle for low mass transfers. For large mass transfers the yield increases slowly with decreasing angle. At 443 MeV a large contribution from negative angles is present. σ_QF accounts for more than 65 % of the reaction cross section σ_R at 443 MeV and for more than 50 % at 365 MeV. The upper limit on CF is about 10 % of σ_R, and σ_PDis of the order of 25 % of σ_R.     

Branch-and-bound methods for solving systems of Lipschitzian equations and inequalities

In this note, we show how branch-and-bound methods previously proposed for solving broad classes of multiextremal global optimization problems can be applied for solving systems of Lipschitzian equations and inequalities over feasible sets defined by various types of constraints. Some computational results are given.This research was accomplished while the second author was a fellow of the Alexander von Humboldt Foundation at the University of Trier, Trier, West Germany.     

Recherche de fission provenant de l'lnteraction 84Kr+209Bi: La fusion entre ions krypton et noyaux lourds est-elle possible?

Fragments emitted in binary fission from complete fusion nuclei have been investigated for krypton induced reactions on heavy nuclei. Cross sections are between 25 and 5% of the total reaction cross section. It is deduced that complete fusion between krypton projectiles and heavy nuclei is a very improbable process. Most of the reaction products seem to result from a very inelastic interaction which looks like very asymmetric fission.     

Theory of ortho ⤥ parahydrogen conversion on paramagnetic and antiferromagnetic surfaces

An attempt is made to establish a theory to explain the many facet experimental results of o ? pH₂ conversion over paramagnetic and antiferromagnetic surfaces in the absence or presence of an externally applied field. The basis of the treatment invokes various nuclear relaxation mechanisms including that for nuclei of an antiferromagnetic above T_N, and a postulate that there might exist pocketful regions in an antiferromagnetic which exhibits ferromagnetic ordering below T_N.     

Shape and size control of Ag2Se nanocrystals from a single precursor [(Ph3P)3Ag2(SeC{O}Ph)2

Monodispersed Ag2Se nanocubes and faceted nanocrystals have been synthesized by hexadecylamine (HDA) induced thermolysis of [(PPh3)3Ag2(SeC{O}Ph)2] in a mixture of TOP (tri-n-octyl phosphine) and HDA in the temperature range 95-180 degrees C.     

GaAs distributed Bragg reflector lasers

An equivalent cavity approach is used to derive the oscillation condition of a distributed Bragg reflector laser. The oscillation frequencies and thresholds are determined graphically. The effect of lossy reflectors is discussed. Several advantages and potential applications of distributed Bragg reflector structures are pointed out. Experimental results on optically pumped GaAs lasers are presented.     

Reduced Brillouin backscatter in CO2 laser-target interaction

Substantially reduced Brillouin reflection has been found for CO₂ laser irradiated high density gas targets. In contrast to high reflectivity (60%) previously observed for underdense hydrogen plasma, total backscatter (stimulated plus specular) is found to peak at 30% for incident intensity 5 × 10¹² W/cm² and decrease thereafter to 18% at 10¹³ W/cm². Ponderomative effects are postulated to account for these observations.     

Determination of components in propolis by capillary electrophoresis and photodiode array detection

The capillary electrophoretic separation of components in propolis, a commonly used natural medicine, was investigated. Optimum conditions for the separation were established. Photodiode-array detection permitted the rapid identification of the components in the samples analysed. The determination of these components, including caffeic acid, dimethylcaffeic acid, isoferulic acid and quercetin, was performed on a commercial propolis sample.