Frequency modulation of a gas laser

A theoretical analysis of a s ingle-frequency gas laser is presented, together with some experimental results. The experimental results are in qualitative agreement with theory.Translated from Izvestiya VUZ. Fizika, No. 6, pp. 111–115, June, 1973.     

Hadronic Production of Heavy QQ Bound States

Several mechanisms for the production of heavy QQ bound states are reviewed. A systematic comparison between model predictions and experimental results is presented. The various theoretical and experimental uncertainties are discussed.     

Theoretical study of the effect of orientation and solvent on energy transfer in bichromophore systems

Results of a quantum-chemical study of the effect of relative orientation of chromophores and solvent on energy transfer in bichromophore systems are presented. The results of theoretical calculations and the experimental data were found to be inconsistent with the prediction of the Förster theory relative to the effect of the orientation factor on the efficiency of energy transfer. It is shown that the effect of solvent on energy transfer is similar to the effect of a connecting bridge in bichromophore molecules. An interpretation of theoretical and experimental results is presented.     

Stable diamagnetic self-levitation of a micro-magnet by improvement of its magnetic gradients

A disc-shaped SmCo magnet with a diameter of 0.85 mm is levitated above a graphite diamagnetic plate at a height of about 14 μm. The magnet is magnetised into a double dipole. The levitation of multipolar magnets above a diamagnetic material was suggested in 1956 by Boerdijk and patented in 1995 by Pelrine, but without any known published experimental results. In this letter, both theoretical and experimental results are presented.     

Non-contact optical fibre phased array generation of ultrasound for non-destructive evaluation of materials and processes

The use of non-contact laser techniques for the generation of ultrasound has extended the limits of the application of traditional ultrasonic techniques. This paper focusses on the use of one such non-contact laser technique, known as ‘optical fibre array’, to generate shear and surface waves. The shear wave experimental directivity pattern results are presented and compared with the theoretical results of a single source and an array source. The experimental directivity results for the surface wave are also presented, and compared with the theoretical results. The data show that the array enhances signal generation in the forward direction for both shear and surface waves. The array gain is also discussed. The receiver for the directivity measurements was a contact piezoelectric transducer.     

Determination of biomass concentration by measurement of ultrasonic attenuation

Experimental results are presented that demonstrate that ultrasonic attenuation can be used to estimate the biomass concentration of a biological suspension. The attenuation approach avoids the temperature sensitivity of established ultrasound velocity test methods, which have hindered their application in process environments. An empirical model is presented for the estimation of the biomass of Microcystis aeruginosa suspensions based on acoustic attenuation, temperature, and frequency, and is compared with experimental results.     

Simulation of Finline structures using the tlm method

A new model of absorbing boundary for the TLM Method, based on absorvence condition on the node, is presented. Numerical and experimental results are presented; and the convergence aspect is discussed.     

Noise in p+nn+ structures based on semiconductor compensated by doubly charged acceptors

The results are presented of a theoretical calculation of the spectra of generation-recombination and diffusion noise in p⁺nn⁺ structures whose base region is compensated by an impurity that creates doubly charged deep acceptor centers. The results of experimental studies of noise processes in such structures are provided. The theoretical results are compared with the experimental data.     

Heterodyne performance of a quasioptical Schottky diode detector: Theoretical and experimental results

A detailed theoretical and experimental study of the heterodyne performance of a quasioptical Schottky diode detector is presented. The experimental results have been obtained by mixing the radiation from a FIR laser with the output of a 67–73 GHz Klystron. The heterodyne signal variation versus various parameters and its relation to the special case of two lasers mixing are described. The mixer characteristics are a NEP value of 2×10^–19W/Hz and a detector bandwidth of at least 9 GHz. Experimental evidence of harmonics generation of submillimetric frequencies at the diode junction is also presented.     

Absolute measurements of rayleigh factor in some pure organic liquids

An absolute light scattering determination method is described. Experimental results are presented for seven organic liquids at 23°C for two wavelengths 4416 Å and 6328 Å. The experimental data are compared with those calculated by theoretical formulas using experimental values of Landau-Placzek ratios and adiabatic compressibilities. A good agreement between experimental and calculated data confirms the validity of “low” values of light scattering factor.     

Ring and jet study on the azimuthal substructure of pions at CERN SPS energy

We have presented an investigation on the ring- and jet-like azimuthal angle substructures in the emission of secondary charged hadrons coming from ³²S–Ag/Br interactions at 200 A GeV/c. Nuclear photographic emulsion technique has been employed to collect the experimental data. The presence of such substructures, their average behaviour, their size, and their position of occurrence have been examined. The experimental results have also been compared with the results simulated by Monte-Carlo method. The analysis strongly indicates the presence of ring- and jet-like structures in the experimental distributions of particles beyond statistical noise. The experimental results are in good agreement with I M Dremin idea, that the phenomenon is similar to the emission of Cherenkov electromagnetic radiation.     

Vibration of bimodular sandwich beams with thick facings: A new theory and experimental results

This study deals with both analytical and experimental investigations of three-layer beams with cores of polyurethane foam and facings of unidirectional cord-rubber. Both of these materials are bimodular (i.e., having different behavior in compression as compared to tension). The new theory presented is a shear-flexible laminate version of the well-known Timoshenko beam theory, which, due to the bending-stretching coupling present in the bimodular case, results in a coupled sixth-order system of differential equations. In this theory, a separate derivation is presented for the shear correction factor. Due to the discontinuities in the normal stress distribution and the bimodularity, the shear correction factor is much different than the classical homogeneous material value of $\text{5}\text{6}$. Theoretical and experimental results are presented for the frequencies of the first three modes of vibration for a pin-ended beam without axial restraint. This work is believed to be the first devoted to vibration of bimodular materials in a sandwich configuration.     

Research on chemical and discharge oxygen-iodine lasers

Novel methods and device configurations for singlet oxygen and atomic iodine generation were proposed and investigated for operation of the chemical or discharge oxygen-iodine lasers (COIL/DOIL). A chemical centrifugal spray generator of singlet oxygen was developed, based on the conventional chlorine-basic hydrogen peroxide chemistry. Results of theoretical and experimental investigation of the generator parameters are presented and compared with parameters of other generator types. A design of experimental device for singlet oxygen generation by means of the hybrid DC arc and RF plasma jet is presented. An alternative method of atomic iodine generation by a radiofrequency discharge decomposition of iodine compounds like CH₃I or CF₃I is described employing advanced experimental configuration. Some representative experimental results of this investigation are presented.     

Form factors of Al

The appropriateness of Harrison's pseudo-potential for Al is re-examined by determining the model parameters from experimental data. The artificial cut-off of the form-factors is shown to be redundant. Satisfactory results are obtained from the presented scheme.     

Experimental researches of propagation of acoustic compression pulses in copper wires

The results of experimental research related to the propagation of elastic-plastic compression pulses in polycrystalline copper wires are presented. We have developed a technique of generating compression pulses with amplitudes of pressure exceeding 100 MPa; this essentially exceeds the elasticity limit of copper. This allows us to carry out the research for the propagation of compression pulses in copper wire (as simples). Significant influence of the pulse amplitude on its spectrum, velocity and absorption will be discussed. The experiments showed that as the amplitude of the pulse increase the pulses velocity is decreased and absorption will be increased. The pulse spectrum also changes correspondingly. The analysis and discussion of experimental results will be presented through the context.     

The electronic structure,x-ray photoelectron and emission spectra of YOF

The results of electronic structure calculations for YOF are presented, making use of Xα-DVM together with experimental X-ray photoelectron and emission spectra for this compound. Three versions of calculations have been performed, depending on the relation between oxygen and fluorine charges in the [YO₄F₄] cluster. The interpretation of experimental spectra is carried out on the basis of these calculations.     

Radiative muon capture on hydrogen

The radiative capture of negative muons by protons can be used to measure the weak induced pseudoscalar form factor. Brief arguments why this method is preferable to ordinary muon capture are given followed by a discussion of the experimental difficulties. The solution to these problems as attempted by experiment #452 at TRIUMF is presented together with preliminary results from the first run in August 1990. An outlook on the expected final precision and the experimental schedule is also given. Talk presented by W. Bertl at the Symposium “The Future of Muon Physics” in Heidelberg, Germany, May 7–9, 1991     

Realization of quantum correlation transfer between twin beams by conditional preparation technique

A conditional quantum correlation transfer is demonstrated experimentally for continuous variables by employing two pairs of twin-beams states. In present paper, the quantum correlation of twin beams is indicated by loss coefficient or “gemellity”, which is the remaining noise on the intensity difference normalized to the shot noise level. The quantum correlation between two initial idler beams with loss coefficient of 0.4 was conditionally transferred from two pairs of initially independent twin beams with loss coefficient of 0.2. A theory of conditional quantum correlation transfer and comparison between experimental results and theoretical prediction are also presented. The experimental results agree with the theory well.