Table of contents

We have shown that it is possible to deduce a modified form of R-matrix and the corresponding Yang-Baxter equation in case of non-ultralocal integrable system, by following a new approach to the problem.

This paper is concerned with the various non-standard entropic measures (so-called f-entropies) for the probabilistic uncertainty of a stochastical object. We present the mathematical definitions of the f-entropies and discuss their possible use in physics. We also propose various non-standard measures of the degree of organization in probabilistic systems.

A measurement system capable of doing automated one to one quantum Hall effect calibration of ordinary wire wound standard resistors kept at room temperature has been constructed. The relative resolution of the system is 10⁻⁷, but due to the lack of temperature stabilization of the standard resistors the total relative uncertainty is 10⁻⁶. The quantum Hall samples used in the calibration are GaAlAs/GaAs heterostructures grown on the Molecular Beam Epitaxy system at the H. C. Ørsted Institute and also processed and mounted there. The quantum Hall samples are demonstrated to allow comparisons at least down to 2 × 10⁻⁹ level. Detailed description of techniques for sample preparation and measuring equipment are presented. Furthermore examples are given of the actual calibration of resistors as well as some concluding remarks about the calibration set-up, which is under construction at the Danish Institute of Fundamental Metrology.

It is shown that preformed-cluster models are equivalent with fission models, used to describe in a unified way cluster radioactivities and α decay. For the first time cluster preformation probability is interpreted as the penetrability of the prescission part of the barrier. A linearized universal curve of each kind of cluster radioactivity is derived in the range of mass numbers detected up to now. The corresponding formula describes well the general trend of experimental data. The need for shell effect correction is illustrated on α decay of 124 even-even emitters.

Coherence effects in electron excitations in heavy ion-atom collisions are discussed, and new methods to treat the role of residual interactions are suggested. Among experimental consequences may emerge new predictions of energy variations in e⁺ e⁻ pair production probabilities.

In continuation of our previous work on the quintet transitions 1s2s2p²⁵P-1s2s2p3d⁵P^o, ⁵D^o, results on other n = 2 - n' = 3 quintet transitions for elements N, O and F are presented. Assignments have been established by comparison with Multi-Configuration Dirac-Fock calculations. High spectral resolution on beam-foil spectroscopy was essential for the identification of most of the lines. For some of the quintet lines decay curves were measured, and the lifetimes extracted were found to be in reasonable agreement with MCDF calculations.

A recently proposed method for calculating intensities of molecular radiative transitions has been applied for soft X-ray fluorescence, absorption and emission spectra involving core ionized and core excited states of CO₂ and CO. The initial carbon and oxygen core states and final valence states are described by multiconfigurational wave functions separately optimized with sets of molecular orbitals that are mutually nonorthogonal. The assignments of energies and intensities are found to be in good agreement with those obtained in experimental X-ray emission spectra and with those deduced from EELS absorption spectra, the latter simulating X-ray absorption, when data on transition energies and oscillator strengths are available. Molecular orbitals and symmetry assignments for emission spectra from neutral core excited states can be proposed based on the present calculations.

The emission spectrum of neutral titanium has been analysed in the region 1900-55 000 Å. More than 3300 lines have been identified as belonging to the Ti I spectrum, connecting 439 energy levels. Over 100 new energy levels have been found. Almost 15% of the previously listed levels have been discarded but a majority of these could be reinstated at new positions. For the registrations in the infrared and visible wavelength regions, the Fourier transform spectrometer at the National Solar Observatory, Kitt Peak, has been used, while the recordings in the ultraviolet are from the 10.7-m Eagle spectrograph at the National Bureau of Standards (now the National Institute of Standards and Technology), Washington DC

The influence of phase memory under collisions on the field work and the light induced drift (LID) effect of two-level gas particles is studied. It is shown that the phase memory effects may lead to the case where about half of the particles interacting with radiation amplify the incident radiation. The integral absorption coefficient for this remains positive due to growing radiation absorption by another half of the particles. It has been found that the phase memory strongly affects the LID under v ≫ k (v is the collision frequency, k is the Doppler line width): calculation of LID without regard for the phase memory can lead to underestimation of the LID effect value by a factor of (v/k)² ≫ 1. Interaction of the particles in the hard sphere model is used to illustrate that the phase memory begins to affect the LID when the relative difference of the transport cross-sections of the particles is ground and excited states is small: Δσ/σ ≲ /R, where is the de Broglie wavelength at thermal velocities, R is the sphere radius.

In this work we use nonlinear sheath capacitance properties in low density plasma to produce parametric amplification of an r.f. signal in the high frequency band (H.F.).

The experiment has been carried out in the linear mirror device LISA of the Universidade Federal Fluminense (UFF), where a helium plasma was produced by a radio-frequency source of 30 MHz with a power which can be varied from 10 watts to 100 watts.

The experimental results show a r.f. signal amplification at 5 MHz with a transducer gain of 5.7. It shows good agreement with the theoretical results of a classical analysis of parametric amplification with a nonlinear device.

Analytical treatment of the linear stability of a thin, dilute rotating electron layer propagating in a rippled waveguide is presented. The vacuum properties of the rippled conducting walled waveguide are approximated by the disc loaded waveguide dispersion relation. An expression of the growth rate for TM mode of the waveguide is obtained. Results are plotted for TM₀₁ and TM₀₂ modes as a function of beam azimuthal mode number l of the beam space charge mode. As the mode number l increases, the growth rate for TM₀₁ and TM₀₂ modes takes a minimum value for a certain l and then it shows an increase. This can be understood by noting that the beam waveguide resonant backward wave oscillator interaction is highly azimuthal mode dependent.

EPR of Mn²⁺ doped in Co(HC₄H₂O₄)₂ · 4H₂O single crystals has been studied at room temperature and at liquid nitrogen temperature using X-band frequencies. The spin-Hamiltonian parameters were caculated. Mn²⁺ has been found to substitute for Co²⁺. Observation of resolved Mn²⁺ spectrum and broadening of the resonance lines on decreasing the temperature have been explained on the basis of host spin-lattice relaxation narrowing. The T₁ of Co²⁺ has been estimated to be ≈8.3 x 10^-12S at 300K.

Differential incoherent scattering cross-sections in the elements Sc, Y, La, Ce, Gd, Dy, W, Pt and Pb have been determined in the angular range 30-130° at Photon energies 145 and 320 keV with a 5.1 cm × 5.1 cm NaI(Tl) spectrometer using a ND-60 multichannel analyser. The results are compared with the recent theoretical values to assess the influence of electron binding. The experimental S(X, Z) values are employed to deduce the differential incoherent scattering cross-sections in conjunction with the Klein-Nishina free electron values. The results show a clear deviation from the K-N values at lower angles, the deviations are also seen to increase with increasing Z. A comparison with the data of Hubbell et al. reveals a good correspondence between theory and experiment at all angles except at the lowest.

Sm_1−x Tb_xS (x = 0.16 and 0.20) and Sm_0.75 Tm_0.25S alloys have been studied using X-ray Absorption Near Edge Structure (XANES) technique to investigate the valence states of Sm and the substituents, Tb and Tm. The Sm L_III absorption edge data provide direct evidence for the intermediate valence of Sm in both systems, on the other hand, the L_III absorption edges of Tb and Tm indicate a purely trivalent ground state of these in the alloys. Their lattice parameters measured by XRD show a fair agreement with the XANES results.