Note on wave propagation through a periodic rectangular wave-guide containing ferrite slabs

Wave propagation through a rectangular wave-guide loaded with periodic ferrite slabs has been considered. Numerical computations for the ratio of amplitudes and the phase shift has been made for the first three harmonics only.I take this opportunity of thanking Dr. S. C.Dasgupta and Dr. S. S.Baral for suggesting this investigation and for their guidance in preparing this note. I also wish to express my gratitude to the C.S.I.R. for financial support as a Senior Research Fellow.     

Spectroscopic studies of Ni2+ in calcium tartrate tetrahydrate

The optical absorption spectrum of a single crystal of calcium tartrate tetrahydrate, doped with Ni²⁺ ions, is investigated at laboratory and liquid nitrogen temperatures. From the analysis of the unpolarised and polarised spectra, the site symmetry of the Ni²⁺ ion is attributed to an elongated octahedron with a small tetragonal (C_4v) distortion.The analysis results in the following crystal field parametersB=875 cm^–1,C=3980 cm^–1,Dq=900 cm^–1, Dt=32cm^–1.The authors wish to express their thanks to the Head of the Department of Physics, I.I.T., Madras for providing the facilities to conduct experiments on a Cary-14 spectrophotometer. They wish to express their thanks to Prof. S.Radhakrishna (I.I.T., Madras) and Prof. S.V. J.Lakshman (S.V. University) for thier interest in the work. The authors are grateful to the U.G.C. (India) for financial assistance.     

MACRO, a large-area detector at the Gran Sasso Laboratory

Summary MACRO is a large-area detector to be installed in hall B of the Gran Sasso Laboratory. Making use of scintillation counters, plastic streamer tubes, and track-etch detectors, it is designed to search for superheavy magnetic monopoles beyond the Parker bound, high-energy gamma and neutrino cosmic sourcs, and, more in general, exotic phenomena in the cosmic radiation. MACTO is an acronym for Monopole, Astrophysics and Cosmic Ray Observatory. The present collaboration: Bari(**)C. De Marzo, O. Erriquez, N. Giglietto andF. Posa. Bologna(**):M. Attolini, F. Baldetti, G. Giacomelli, F. Grianti, A. Margiotta andP. Serra. Caltech:B. Barish, C. Lane andG. Liu. CERN:P. Musset, G. Poulard andH. Sletten. Drexel:R. Steinberg. Laboratori Nazionali di Frascati dell'INFN:G. Battistoni, H. Bilokon, C. Bloise, P. Campana, V. Chiarella, A. Ciocio, A. Grillo, E. Iarocci, A. Marini, A. Rindi, F. Ronga, L. Satta, M. Spinetti, L. Trasatti andV. Valente. Indiana:S. Ahlen, B. Brabson, R. Heinz, S. Mufson, H. Ogren andP. Smith. Michigan:J. Musser, J. Stone, L. Sulak andG. Tarlé. Pisa(**):C. Angelini, A. Baldini, C. Bemporad, A. Cnops, V. Flaminio, G. Giannini, R. Pazzi andB. Saitta. Roma(**):G. Auriemma, M. De Vincenzi, E. Lamanna, G. Martellotti, S. Petrera, L. Petrillo, P. Pistilli, G. Rosa, A. Sciubba andM. Severi. Texas A&M:R. Webb. Torino:M. Arneodo, G. Borreani, P. Giubellino, F. Marchetto, A. Marzari, S. Palestini andL. Ramello.Virginia Tech:S. Torres andP. Trower. (**) Sezione INFN e Dipartimento di Fisica dell'Università.     

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.     

R-matrix plus potential analysis of unbound states of33S

Single channel single levelR-matrix plus potential analysis of the resonances observed in the³²S(n, n) reaction for the neutron energy lying from 20–1100 keV has been carried out to determine the properties of these resonances. This analysis is further supported by a single channel multilevelR-matrix analysis of the data. Spectroscopic factors for the resonances have also been calculated by ourR-matrix method. Its comparison with those obtained bydwba analysis of the (d, p) data is 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.     

Treatment of bcc transition metals on a modified CGW model

The vibrational spectrum and specific heat of three bcc transition metals -iron, chromium and tungsten are computed on the basis of modified Clark-Gazis-Wallis angular force model which considers volume forces of Krebs' nature. The calculations are made using the Blackman's root sampling technique for a discrete subdivision in wave-vector space. The calculated lattice specific heats and the effective Debye temperatures are compared with the available experimental data. The results show a reasonably satisfactory agreement with the experimental observations.The authors are highly thankful to Dr.Jyoti Prakash, Dr. S.Chandra for helpful discussions. One of them (H. L. K.) is thankful to C. S. I. R. India for the award of J. R. F. The computational facilities received from the I. I. T. Kanpur are also acknowledged.     

On preparation of oriented foils from ferromagnetic materials for tem

A method of preparation of oriented foils for transmission electron microscopy from ferromagnetic material by jet electropolishing and chemical dissolution of thick edge of perforated disc is described. The minimization of the mass of a ferromagnetic foil in the microscope results in an important reduction of additional astigmatism. An image of better quality is easily obtained. The case of preparation of foils from Fe-3% Si alloy by this method is treated in detail. The principle of the suggested method is applicable to other ferromagnetic materials.The authors are particulary grateful to S. J.Gergis for initial experiments with the protecting liquid and to I.Kaová for her help in polishing experiments with the ELA device.     

The Clebsch-Gordan coefficients of SU(4)

A set of recurrence relations connecting the matrix elements of finite transformation belonging to the same irreducible representation of SU(4) is used to obtain a wide class of matrix elements. An expression for the Clebsch-Gordan coefficient is obtained by integrating the product of three matrix elements belonging to three different irreducible representations of the group. The symmetry properties of the matrix elements and the Clebsch-Gordan coefficients are discussed.The author is grateful to Professors S.Datta Majumdar and G.Bandyopadhyay of the Department of Physics, I.I.T., Kharagpur, for many helpful discussions. This work was supported by the C.S.I.R., Government of India.     

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.     

A Mössbauer and X-ray diffraction study of nonstoichiometry in magnetite

The paper deals with the applicability of Mössbauer spectroscopy and X-ray diffraction methods for the determination of the deviation of magnetite from stoichiometry. The results show that among the data obtainable by both methods, the ratio of intensities of two partial spectra composing the Mössbauer spectrum of magnetite enables to evaluate the deviation of magnetite from stoichiometry quantitatively.The authors express their gratitude to Prof. Dr. Ing. J.Cirák who enabled them to perform all measurements of Mössbauer spectra at the Department of Nuclear Physics and Technics, Slovak Technical University, Bratislava. The authors are also indebted to Ing. P.Holba (Institute of Solid State Physics, Czechoslovak Academy of Sciences) and to Ing. Z.Drbálek (Research Institute of Sound and Picture) for the preparation of magnetite samples, and to Mr. P.Chaloupek (Faculty of Mathematics and Physics, Charles University, Praha) for computer calculation of lattice constants. The aid provided by members of the G. V. Akimov State Research Institute for the Protection of Materials, Dipl. Chem. K.Jendelová who carried out chemical analysis of the samples and Ing. K.Turecká who took part in X-ray diffraction measurements, is gratefully acknowledged.     

Geodesic multiplication and BRST-like operators

Construction of the local geodesic multiplication is described. Following S. Okubo with some modifications, two families of local geodesicbrst-like cohomologies are introduced. Some problems arising from these constructions and possible applications are discussed.     

Estimation of bond energies from mulliken overlap populations

Estimations of the bond energies from Mulliken overlap populations are taken. The strength of a bond is undoubtedly connected with the density of electrons constituting this bond. In the present paper the electron densities _i ^bond belonging to the particular bonds are represented by the total overlap populations defined byMulliken. The heat of atomization of the molecule is subdivide in the ratio of these electron densities _i ^bond belonging to the individual bond.My thanks are due to Drs. S.erný, Z.Knor, J.Pancí and R.Zahradník for their interest and stimulating discussions.     

On Gell-Mann's λ-matrices,d- andf-tensors,octets, and parametrizations ofS U (3)

The algebra ofS U (3) is developed on the basis of the matrices _i ofGell-Mann, and identities involving the tensorsd _{i j k} andf _{i j k} occurring in their multiplication law are derived. Octets and the tensor analysis of the adjoint groupS U (3)/Z(3) ofS U (3) are discussed. Various explicit parametrizations ofS U (3) are presented as generalizations of familiarS U (2) results.     

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.     

Study of magnetic interactions of the Fe2+ ions and the protons of crystallization water in FeSO4.n H2O hydrates

The paper deals with a study of interactions of protons in crystallization water of paramagnetic hydrates FeSO₄.n H₂O (wheren=1, 4, 5 and 7). The interaction of protons and paramagnetic ions Fe²⁺ and the nuclear dipole-dipole interaction of protons have been studied by means of the parameters expressing the dependence of the second moment of the proton nuclear magnetic resonance (NMR) spectrum on the external magnetic field, by means of the volume magnetic susceptibilities and the relaxation timesT ₁ of the investigated series of hydrates.We are grateful to Prof. Dr. hab. Z.Pajak, director of Department of Radiospectroscopy IF UAM in Poznan, and to his coworkers Dr. J.Kapturczak, Dr. K.Jurga, Dr. S.Glowinkowski and Mgr. F.Brych for facilitating our measurements mentioned in the paper as well as for a valuable discussion.     

Modulational instability of elliptically polarized transverse electromagnetic wave in a cold plasma

Modulational instability of an elliptically polarized transverse wave in a cold plasma is investigated by the use of Whitham's method of averaged Lagrangian including relativistic corrections. Instability condition and amplitude dependent frequency shift are derived.The authors wish to thank the referee for his valuable suggestion to improve the paper. The award of a Junior Research Fellowship to one of the authors (S.Sihi) by CSIR, India is gratefully acknowledged.     

Thermopower in the Anderson model of semiconducting glasses

The thermoelectric power in the Anderson model of electrons in localized states in the mobility gap of semiconducting glasses interacting by attractive forces is calculated at low temperatures. Under some conditions, a transition from the activated form ofS to S=const at low temperatures is predicted. In connection with the activated character of the conductivity, it well corresponds to the experiment on some chalcogenide glasses.The author would like to thank ing. V.Cháb for communicating him the experimental data on As₂Te₃TI_x prior to publication.     

Thermodynamic theory of finite ferroelectric crystals with surface energy

The phenomenological Landau theory of phase transition is generalized to finite ferroelectric crystals with surface energy. Restrictions of the expansion imposed by the symmetry of the surface are considered, and further analysis is devoted to a special case. The solution in the approximation of constant polarization is discussed. Single domain states of a plate are analysed in greater detail.The authors are very grateful to Dr. V.Janovec and Dr. J.Fousek of the Czechoslovak Academy of Sciences for helpful discussions. Thanks are due to Prof. L.Valenta for the valuable discussions dealing with the magnetical analogical problem.