The quark model and exchange degeneracy

The quark model and exchange degeneracy of leading Reggeon contributions to quark-quark scattering amplitudes are combined for deriving a number of relations on polarizations, the real parts of forward scattering amplitudes and total cross sections. The comparison of these relations with experimental data is discussed.The authors are grateful to Ya. I.Asimov, E. M.Levin and L. L.Frankfurt for their interest in this work.     

Kinetics of spinodal decomposition in Fe-Si alloys

The spinodal decomposition in the two-phase region of the phase diagram (B₂ + DO₃) of Fe-Si alloys is studied on the basis of the generalized diffusion equation. The configurational free energy is calculated in the Bragg-Williams-Gorsky approximation. The effect of the coherency strain energy is estimated. In the main part of the paper the Langer's method is applied in the investigation of the coarsening rate in Fe-Si system with a good agreement with experimental data in a broad range of annealing times. The limitations of such approach are discussed with respect to the Khachaturyan's theory of the periodic distributions of decomposition products.The author is grateful to Dr. F.Kroupa for his guidance and encouragement during the course of this work, to Dr. S.Libovický and Dr. A.Gemperle for discussions of their latest experimental results.     

On ferromagnetic resonance damping in metals

The Landau-Lifshitz damping coefficient is defined in terms of spin-orbital torque correlations in the one-electron model and estimated as a function of the orbital collision frequency. The formal results are compared with previous studies and the results of a numerical calculation for nickel are compared with known experimental data.I would like to thank Dr. L.Hodges for a copy of his thesis and Dr. A. V.Gold, Dr. J. R.Anderson, Dr. V.Dvoák, Dr. Z.Frait and Mr. M.Kolá for valuable discussions at various stages of this work.     

The role of effective two-nucleon potential in the electric monopole transition in C12 and O16

In the present paper the Shiff's model is used to explain the O⁺-transition mechanism in nuclei. In contrary to the Shiff's study more realistic effective potentials suggested bySiemens andSprung andBanerjee are applied. They give good results.The author would like to thank Prof. I.Úlehla and Z.Pluha for encouraging interest in this work.     

Relaxation time measurements in zinc alloys

Relaxation times obtained by means of de Haas-van Alphen measurements have been investigated in dilute alloys ofZnMn andZnAg. In both series of alloys measurements have been made on the needle, monster and lens sections of the Fermi surface. In theZnMn alloys, which exhibit a Kondo resistance minimum, the results analysed followingPaton andMuir [2] give a value for the s—d interaction constant,J, agreeing with this previous work. Similarly, an analysis followingNagasawa [4] givesJ values in agreement with that work. The situation posed by the existence of these two approaches, concerned as they are with opposite extreme limits, is discussed. In addition, the behaviour found in the other periods ofZnMn is discussed; here the effects seen on the needles are completely absent. A preprint of this paper was introduced during the discussion at the Conference on Electron Mean Free Paths by the Chairman of the Session, Dr.D. Shoenberg.     

Air-exposure effect on the resistivity of thin bismuth films

A survey of previous studies on vacuum deposited metal films shows that in high frequency measurements, explicit reference to the effect of air-exposure is not made. The present work on bismuth films (in-situ and air-exposed) at dc and rf frequencies, carried out mainly to study the air-exposure effect, shows that in-situ dc and rf and exposed rf all show nearly the same resistivity for thick continuous films. But air-exposed dc film resistances, when compared to in-situ dc resistances, show that the grain boundary reflection coefficient, R _gin Mayadas-Shatzkes model changes from 0·2 to 0·6. This is shown to be due to the grain boundary oxidation. The result is substantiated by rf measurements.     

Adiabatic time-dependent Hartree-Fock theory with the consistency condition

Adiabatic time-dependent Hartree-Fock (atdhf) theory, including the authors’ work in this field, has been summarised. In response to the criticism of Yamamuraet al the role of curvature in preventing the choice ofpure rpa mode as the solution near the static Hartree-Fock minimum has been discussed.     

The S-matrix in classical mechanics

In the Hilbert-space version of classical mechanics, scattering theory forN-particle systems is developed in close analogy to the quantum case. Asymptotic completeness is proved for forces of finite range. Infinite-range forces lead to the problem of stability of bound states and can be dealt with only in some simple cases.It is a pleasure to thank Prof.L. Motchane for his kind hospitality at the I.H.E.S., where most of this work was done, and where the author profited from discussions withD. Ruelle andO. E. Lanford.     

The existence of (n, γf) process on235U nucleus and uranium X-ray yields

The measurement of X-rays emitted before the fission of²³⁵U induced by resonance neutrons is described. Preliminary results show the dependence of the X-ray yield on fission width _f. It is explained on the bases of the existence of the two-step (n,f) process. The estimate of the width of the (n,f) process is of the order of 4 MeV and the-transitions taking place before fission of²³⁶U compound nucleus are mostly of the M1 type.In conclusion the authors would like to express their gratitude to L. B.Pikelner for many useful discussions, to I. M.Salamattn and A.Mateeva for the programme supply of the experiment, V. G.Tisin, A. A.Bogdzel, Yu. I.Kolgin and N.Chikov for taking part in the different steps of the work. The authors are also grateful toYu. P.Popov and I.Wilhelm for taking interest in the work.     

A study of the plasma column with attention to the region near the wall

The ambipolar diffusion problem in a positive column is studied when charged particle inertia, heating and the mobility variation of positive ions in the radial electric field are taken into consideration. The atomic ion motion in their respective parent gases is approximated by the hard sphere model. The problem was also solved by approximate methods and compared with the precision numerical calculations. A simple formula for number density of charged particles at the boundary plasma-sheath was found.The authors would like to thank Professor .Veis for the support of this work. We are also grateful to Dr. I.Koinár and Dr. V.Jukl for their guidance in computer programming.     

A generalization of variable phase equation

This paper describes a new formulation of phase equation based on a decomposition of wave function into two parts. An equation closely related to the WKB approximation is derived and solved numerically with exponential and Wood-Saxons potential.The author is indebted very much to Doc. J.Kvasnica CSc for the valuable discussions and interest in this work.     

Weak gamma-ray transitions of 1·440 MeV and 1·460 MeV in the decay of207Bi

The single gamma-ray spectra of²⁰⁷Bi were measured with 32 c. c. Ge(Li) detector. Evidence of gamma transitions of energies 1·440 MeV and 1·460 MeV is found. The relative intensity of these lines has also been estimated by measuring their photopeak areas. There is no evidence of the weak 0·9 MeV gamma as reported earlier (Alburger D. E.,Sunyar A. W., Phys. Rev.99 (1955), 695;Jar Dine L. J., Phys. Rev.C 11 (1975), 1385).The authors are grateful to the Director of the Saha Institute of Nuclear Physics, Calcutta for providing the facilities to work with the Ge(Li) detector at the Institute. We wish to thank Professor B. B.Baliga of the Institute for valuable discussions. Our thanks are due to Professor B. P.Singh, Head of the Physics Department of Roorkee University, Roorkee, for providing us with the facilities to perform the coincidence measurements in his laboratory.     

Spin d'une Particule

The purpose of this note is to study the spin of a free relativistic particle, using the language defined by Mr.Laurent Schwartz. In contradistinction with what has been done often, we work completely in the Hilbert space of the particle, without using (improper) pure states of energy-momentum. We first explain our formalism in a general basis-independant way and then perform the whole calculus on a particular example. The probabilities of spin orientation along a quantization axis depend on the observer.     

ac anddc electroluminescence in CaS:Cu,Sm phosphors

Theac anddc electroluminescence in CaS:Cu, Sm have been investigated. The luminescence spectra show three peaks in the visible region. The brightness-voltage dependence satisfies the relationB=B ₀ exp (−b/V ^1/2) with two modes of variation. The nature of this dependence indc andac at different frequencies is discussed. The electroluminescence brightness also depends on the temperature of the phosphors and shows a peak around 80.0;C. The electroluminescence efficiency increases with applied voltage up to 2200 V and this dependence on V is explained on the basis of a transport process of the Schottky emission type.     

The temperature dependence of some thermodynamical quantities of ferromagnetic alloys in the region of magnetic phase transition

This paper deals with the behaviour of ferromagnetic alloys in the region of magnetic phase transition. The temperature dependences of spontaneous magnetization, magnetic susceptibility and specific heat are discused. The theoretical results are compared with experimental data.I wish to thank Professor L.Valenta for his kind guidance and advice given to me during my work on this paper.     

One- and two-nucleon emission following the nuclear radiative pion capture

Decay channels in the radiative pion capture reactions are discussed and their respective yields calculated. Specific consequences of a recently suggested quadrupole excitation mode in the ( ^–,) reaction are found and their experimental investigation is urged. A yield of about 19% of the total decay was estimated for the two-nucleon decay channel even for the light nuclei like¹⁶O.On leave of absence fromthe Institute of Nuclear Physics, Czechosl. Acad. Sci., 250 68 e, Czechoslovakia.We a re grateful to the members of Lausanne-Münich-Zürich collaboration, particularly to C.Joseph, G.Strassner and P.Trüol for supplying us with the experimental results prior to publication. M. G. also thanks them and R.Wünsch for interesting discussions. We are grateful to R. A.Sakaev for his help at an early stage of this work.     

Mean energy of electrons in the oxygen discharge plasma

The mean energy of electrons in the homogeneous form of the positive column in an oxygen discharge is determined. The mean energy of electrons is calculated from double-probe characteristics under the assumption of a Druyvesteyn distribution using volt-equivalents of the electron temperature. The relation between the mean energy of electrons andE/p is compared with the theoretical results of another author. As a result of this comparison it can be concluded that for some discharge conditions the energy distribution of electrons is very close to a Druyvesteynian. We also analyze the influence of the negative ions on the double-probe characteristics.The author is obliged to Dr. O.tirand, Dr. L.Pekárek and Dr. J.Skála for their support of this work and helpful comments.     

The CNDO-MO study of oxygen impurity states in AlN crystal

Deep levels due to oxygen impurity have been theoretically studied by the quasimolecular approach. The calculation of the orbital spectra was performed using the CNDO/2 method. Some important quantities (transition energies, width of valence band, effective charges etc.) were estimated. The results obtained agree qualitatively well with experimental data but quantitatively are still about 20% in error. Some reasons for the above discrepancy are briefly discussed.The authors are very grateful to Dr. J.Kubátová and Dr. S.Paesová for helpful discussions of the experimental investigations of aluminum nitride and to Dr. J.Pastrák for his interest in this work and discussion of results.     

On wave equations for viscous fluids

This paper deals with wave equations describing small-amplitude disturbances in horizontally stratified, continuously varying, viscous fluids; gradients of the static pressure and of the coefficient of viscosity are neglected. A set of equations in first-order matrix form, which describes coupled longitudinal and transverse disturbances, is treated by the methods ofClemmow andHeading and ofHeading.The work of this paper could be extended in a number of ways; for example, the effect of a gravitational field could be included, and the coefficient of viscosity could be allowed to vary with position.     

Vertical sea level meson-neutrino spectrum derived from the Goddard Space Flight Center measured nucleon spectrum

The vertical sea level meson neutrino spectrum has been derived from the measured primary nucleon spectrum of Goddard Space Flight Centre Group by using the model of Pal and Peters. The calculated result agrees with the work of Osborne et al. at high energies.The author is thankful to Prof.Yash Pal and Prof. J. L.Osborne for sending their works. Thanks are due to C.S.I.R., Govt. of India for financial support.