Theory of optical couplers

The propagation of solitons through optical couplers is studied here in this paper. Both the twin-core couplers as well as the multiple-core couplers are considered here in this paper. The parameter dynamics of the solitons that are governed by the coupled generalized nonlinear Schrodinger's equation, due to non-Kerr law nonlinearity, has been obtained for such couplers.     

Particle multiplicities in the fission-like reactions of 340 MeV Si on Th

Pre-scission and post-scission multiplicities of neutrons and alpha particles have been simultaneously measured for the fission-like reactions of 340 MeV ²⁸Si on ²³²Th. Dynamical model calculations using HICOL code predict that about 90% of the observed events are of quasi-fission type while the remaining 10% are from compound nucleus fission decay. Moving source fits were carried out to the observed neutron and alpha particle spectra, measured at different angles with respect to the fragment directions. The pre-scission and post-scission neutron multiplicities are deduced to be 8.7±2.0 and 9.4±2.0, respectively. The corresponding multiplicity values for alpha particles are found to be 0.22±0.08 and 0.1±0.03. From the measured post-scission neutron multiplicity, it is inferred that about 65±20 MeV of the initial excitation energy remains at scission. This may be compared to the value of 85±30 MeV estimated from PACE2 statistical model calculations, adjusted to reproduce the measured pre-scission neutron multiplicity. From a comparison of the Statistical Model predictions with the measured pre-scission neutron multiplicity, the fission delay is estimated to be of 5⁺⁷₋₃×10⁻²⁰ s which overlaps with the average duration of fission-like process from the contact to the scission point (2×10⁻²⁰ s) as determined from HICOL-based dynamical calculations. For the delay time deduced as above, the pre-scission alpha particle multiplicity calculated by the PACE2 code is about a factor two larger than the experimental one, demonstrating the difficulties in modelling the alpha particle emission from highly elongated shapes that characterize the fissioning system from the contact point to scission.     

Fluctuation study of pionisation in ultrarelativistic nucleus-nucleus interaction

The scaled factorial moments and the multifractal moments have been investigated in differentη-intervals to study the dynamical fluctuation of pions produced in 200 AGeV³²S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process.     

Vanadium Oxide: From Gels to Nanotubes

Vanadium oxide nanotubes (VO _x -NT) have been prepared by mixing hexadecylamine with V₂O₅·nH₂O gels. This procedure was followed by an hydrothermal treatment (150–180°C, 2–7 days) which leads to a large quantity of VO _x -NT. SEM and XRD analysis have been used to optimize the temperature and reaction time required for production of VO _x -Nt and morphology of the nanotubes investigated by TEM.     

Tetra-t-butyl magnesium phthalocyanine on gold: electronic structure and molecular orientation

In this work we have investigated the electronic structure and the molecular orientation of (t-Bu)(4)PcMg (tetra-t-butyl magnesium phthalocyanine) on polycrystalline and single crystalline gold substrates using photoemission spectroscopy and x-ray absorption spectroscopy, and we compare the results to the unsubstituted PcCu (copper phthalocyanine). The C 1s photoemission spectrum is described similar to unsubstituted relatives with an additional component for the aliphatic substituents. The variation of the excitation energy causes distinct differences in the shape of the C 1s spectrum, which is very useful for the analysis of the molecular orientation in the uppermost layer. It is shown that despite of the sterically demanding substituents, ordered sublimed films of (t-Bu)(4)PcMg are accessible, the orientation of the molecules, however, is different from the orientation of the unsubstituted relatives.