Spontaneous emission in longitudinal wiggler and solenoidal magnetic field

Summary In this paper we study the spectral brightness of the radiation emitted by electrons moving in longitudinal wiggler and solenoidal magnetic field. The analysis is based on the evaluation of the Lienard-Wiechert potential retaining the condition of far-field limit. Some features of a longitudinal wiggler are presented and compared with the results relevant to the brightness of the helical wiggler and the solenoidal magnetic field employed in gyrotron-type devices.     

Morphology, bond saturation and reconstruction of hexagonal SiC surfaces

Received: 21 March 1997     

Kinetic aspects of the syntheses using short-lived radionuclides

“ACTIVA” is an activation analysis programme written for small computers (16 to 32 k-words) in FORTRAN-IV. Input-mode for operating commands is interactive, guided with self-explenatory questions. This enables the evaluation of gamma-spectra which could be registered under 4 different conditons (flux, geometry, etc.) with two different counting systems existing in Atominstitute. In each case another data-library with different calibration factors will be chosen and used automaticly. Programme “ACTIVA” is originally designed for gamma-spectra registered with “Loss-Free-Counting” (LFC) electronic with 2×2048 channels, but can be modified for 1024 or 4096 channels easily. Two different multichannel analysers (MCA) can be chosen for data-input: ORTEC-6240 MCA, or NOVALFC (Loss-Free-Counting). The correct energy calibration constants will also be chosen automaticly. The programme has a modular constraction and combined (linked) with overlay technique.     

Application of low energy gamma-spectrometry in rapid actinide analysis for emergency preparedness

For preparedness purposes, a fast and reliable method is essential to quickly assess radioactive fallout in the environment. The rapid determination of certain nuclides such as alpha-emitting actinides is necessary to make initial environmental and agricultural advisories. Therefore, a method using a preconcentration resin and low energy gamma-spectrometry was developed to a fast determination of certain nuclides in soil samples. The preconcentration resin allows samples to be partially purified and then directly measured by gamma-spectrometry without further extraction or separation. The initial gamma-measurement provides fast and accurate determination of certain nuclides such as ²⁴¹Am and ²³⁵U which are normally analyzed by alpha-spectrometry, but require additional time-consuming purification and separation steps. After gamma-spectrometry, the sample may be further processed and analyzed by traditional methods to determine actinides or other nuclides more precisely.     

Fragmentation of some 1,2-epoxyguaianolides

The mass spectra of four guaianolides with epoxy groups of C₁–C₂ have been studied. A mechanism is proposed for the formation of the main ions. The origin of the secondary fragments has been confirmed by measurements of elementary compositions.Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 796–800, November–December, 1980.     

Analysis of electronically nonadiabatic chemical reactions: An information theoretic approach

A practical procedure for the determination of branching ratios for reactions which lead to either excited or electronically ground state products is outlined. The method is applied to four reactions which could (on energetic grounds) produce an electronically excited iodine atom. No case of a complete inversion is found, but one reaction (F + HI) is predicted to yield a statistical, (one half), I^*(²P_1/2) to I(²P_3/2) ratio.     

Investigation of directional solidified Al–Ti alloy

Al–1 wt% Ti alloy was directionally solidified upwards under argon atmosphere under the two conditions; with different temperature gradients (G = 2.20–5.82 K/mm) at a constant growth rate (V = 8.30 μm/s) and with different growth rates (V = 8.30–498.60 μm/s) at a constant temperature gradient (G = 5.82 K/mm) in a Bridgman furnace. The dependence of characteristic microstructure parameters such as primary dendrite arm spacing (λ₁), secondary dendrite arm spacing (λ₂), dendrite tip radius (R) and mushy zone depth (d) on the velocity of crystal growth and the temperature gradient were determined by using a linear regression analysis. A detailed analysis of microstructure development with models of dendritic solidification and with previous similar experimental works on dendritic growth for binary alloys were also made.     

Molecular interaction study through experimental and theoretical volumetric,transport and refractive properties of N-ethylaniline with aryl and alkyl ethers at several temperatures

To investigate the molecular interaction study between secondary amine with aryl and alkyl ether, we report densities, speeds of sound, viscosities and refractive indices of N-ethylaniline (NEA) with aryl (anisole, phenetole) and alkyl (tert-butyl methyl ether) ether over the entire composition regime and in the temperature range of 293.15–323.15 K at 5 K intervals. Various excess and transport properties were derived from the experimental data and the excess parameters were fitted to the Redlich–Kister polynomial equation using multiparametric non-linear regression analysis to derive the binary coefficients and to estimate the standard deviation. Molecular interactions between the unlike molecules were analysed through dipole–dipole interactions, cross-association between the components of the mixtures and H-bond formation. Viscosity and refractive index of the mixtures were predicted through several empirical equations and compared with the experimental results. Prigogine–Flory–Patterson statistical theory was used to predict the excess molar volume results.