The gauge invariance,kinematical singularities and the electro- and photopion production amplitudes

The kinematical singularities connected with the gauge invariance are considered and the conventional sets of invariant amplitudes discussed. A new set of invariant amplitudes for electro-production of pions on nucleons is proposed, which contains the transversal subset of photo-production amplitudes, is free of kinematical singularities and more convenient for practical calculations.I would like to thank Dr. M. Petrá for a valuable discussion on some points, Dr. P. Lichard and Dr. J. Piút for useful remarks and Dr. F. A. Berends for a valuable correspondence. I am also indebted to Prof. Moorhouse for drawing my attention to some important papers and sending me a preprint of one of them.     

Electrical equivalent circuit for the modes of oscillations of piezo-electric bars

The equivalent circuits for odd and even longitudinal, flexural and torsional vibrations of piezo-electric bars were calculated by means of series development for various ways of excitation. The effect of coupling due to internal frictions was neglected.In Conclusion I would like to thank Prof. Dr. V. Petrílka, corresponding member of the Czechoslovak Academy of Sciences, for his tireless interest and help in this work. At the same time I would like to thank all my friends who in any way contributed, particularly Dr. J. Tichy and Dr. A. Apfelbeck.     

Characteristics of equipment for measuring the size of fog droplets and aerosol particles

The principles are developed for a. photometric method of measuring the size of fog droplets and aerosol particles for which the conditionp 1 holds. The scattering pattern of light is constant in the range of size measurements considered. An expression tor the sensitivity of equipment for direct photometry was obtained. An expression is given for the errors introduced by the various elements of the equipment. An attempt is made to define the essential physical features of the metering concept used in the equipment.In conclusion, I express my sincere gratitude to Prof. M. M. Gurevich, Prof, K. S. Shifrin, and Lieutenant Colonel I. A. Manzon for a critical review of this paper and for a number of valuable remarks.     

Phase transition in plasma of electric discharge between parallel plates in air

In high intensity electric discharge in air at atmospheric pressure between parallel plates, during their mutual distance gradually decreasing, there was a plasma compression going on by recombination pressure of decaying peripheral zone of plasma. When the distance between the electrodes was small, there was observed a decrease of pressure and an increase of the cohesive forces in central plasma of the discharge, this being interpreted as a phase transition in plasma —its condensation.In the end I would like to express my thanks to Prof. Dr. S. Veis for his introduction into the problematics of the dense non-ideal plasma.     

Mollwo-Ivey relations for emission bands in copper doped alkali halides

The fluorescence spectra were measured of nine alkali halides with a low concentration of monovalent copper. Relations analogous to Mollwo-Ivey law for F-centers and for lead doped alkali halides were found to be satisfied by the measured wavelengths corresponding to the emission band maxima. The Stokes shifts, however, were here essentially larger as compared to those of lead doped alkali halides. Their order of magnitude is about the same as for F-centers.Dedicated to Prof. Dr. I. Tarján on occasion of his 60th birthday.Cukrovarnická 10, Praha 6, Czechoslovakia.The authors wish to express their appreciation to Dr. M. Lébl, CSc., and Ing. . Barta, CSc., for growing the crystals and to Mrs. I. Velická for the polarographic analysis.     

Internal Bremsstrahlung accompanying non-unique second-forbiddenβ-decay of36CL

The inner Bremsstrahlung spectrum (I.B.) associated wih the non-unique second forbidden-transition of³⁶Cl was measured using a single channel NaI (Tl) scintillation spectrometer. After making all the necessary corrections, the experimental results were compared with the corresponding theoretical distributions due to the KUB, Lewis and Ford, Nilsson, Ford and Martin and Chang and Falkoff. Also a comparison with those calculated according to Nilsson theory after applying the shape correction factor (M. KUB) was done. The measured spectrum is found to show fairly good agreement with M. KUB theory and its found to deviate therafter from all five theories.The authors would like to thank Prof. Dr. M. El-Nadi and Prof. Dr. O.E. Badawy for their suggestions, interest and encouragement.     

Resolution of the lower hybrid current drive spectral-gap anomaly via enhanced toroidal Landau damping

Wave absorption in a torus is found to differ significantly from the classical Landau result. Instead of the isolated resonance atv=/k, the periodic modulation in particles' parallel velocity gives rise to an infinite, discrete spectrum of resonances. The spread of wave absorption over the velocity space leads to an enhancement in damping for the highphase-velocity waves. This mechanism might provide the resolution of the lower-hybrid current drive spectral-gap anomaly without invoking either a spectral upshift or recourse to an anomalous process.I am indebted to Prof. R. Wilhelm for many fruitful discussions as well as for suggesting the applicability of enhanced toroidal Landau damping to LHCD spectral-gap anomaly. I am also thankful to Dr. M. Ballico, Dr. F. Leuterer and Dr. J.-G. Wegrowe for their help.     

Exchange currents and nucleon magnetic moments

We investigate the effect of gluon and pion exchange currents on the magnetic moments of the nucleon using the constituent quark model. We also study the effect of scalar exchange currents connected with the confinement and sigma exchange potentials. We conclude that although individual exchange currents are quite large, the total exchange current contribution is relatively small, due to a cancellation of gluon, pion, and scalar exchange currents.Lecture presented at the Indian-Summer School on Interaction in Hadronic Systems, Praha (The Czech Republic), 25–31 August 1993.I would like to thank my colleagues Dr. E. Hernandez and Prof. K. Yazaki, for their collaboration in this field.     

Does a neutron know that the earth is rotating?

In 1979 we observed the quantum mechanical phase shift of neutron deBroglie waves due to the Earth’s rotation. After the result was published, a number of very nice theoretical papers on the experiment appeared. I have two favorites: The one by M. Dresden and C. N. Yang in which they view the effect as due to the Doppler shift created by reflection from moving mirrors; and the other one by J. J. Sakurai in which he views the origin of the effect as being due to a flux of rotation threading the neutron interferometer loop, in much the same way that magnetic flux threads the electron interferometer loop to create the topological Aharonov-Bohm effect. Here, I would like to place their explanations of the physics of this experiment in juxtaposition with my own understanding of it. This paper is part of the 60th birthday Festschrift for Prof. Bahram Mashhoon.     

Asymmetric biaxial waveguides

The expressions for the propagation constant in the three types of cylindrical asymmetric biaxial waveguides, in which the axes of two media are displaced one from the other, are derived. Taking the wave indexm=0 for an asymmetric wave we reobtain the known result in coaxial waveguides. Withm0 the field intensities increase with increasing the asymmetry. By increasing the size of outer surface the attenuation will be decreased.I would like to express my sincere thanks to Dr. D. Fraitová for her help and to Prof. Hoang Phuong for initially suggesting this problem.     

Anisotropy of the relaxation time in PbTe

The magnetoresistivity of monocrystalline specimens of n- and p-type PbTe is investigated. A small anisotropy of the relaxation time is observed, which diminishes, as does the effective mass anisotropy, with the rise in temperature and concentration.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 24–28, May, 1976.In conclusion, we are grateful to Prof. K. D. Tovstyuk and Dr. P. M. Starik for providing the topic and discussing the results.     

A quasi particle approach to relaxation phenomena

An evolution equation for the relaxation of a nucleus in a metal is derived, assuming that the electronic thermostat is the vacuum of quasi-particles. The relaxation originates in the successive creations of quasi-boson excitations of the electronic system.The author's interest in this subject was aroused through a collaboration with Prof. I. Berkes. He wishes to thank him. It is pleasure to thank also Prof. R. Coussement and Dr. P. Put for many helpfull discussions and for their hospitality at the I.K.S. Leuven.     

Axiomatic restrictions on scattering amplitudes of hadrons

Problems of expsrimental verification of the quantum field theoretical principles by experimental test of any one of physical corollaries of the axiomatic quantum field theory are shortly discussed. A selective review of available axiomatic restrictions on scattering amplitudes of hadrons is given.The author is very indebted to E. P.Sabad, I. Yu.Krivsky, V. I.Kelemen, and Yu. A.Xaveri for the help offered to him during the preparation of this review. The author is especially indebted to Academician N. N.Bogolyubov for his approval of Theorem XXVIII before publishing it in Ref. [67], as well as to Prof. M. I.Podgoretsky (Dubna) and Prof. V. Ya.Fajnberg (Moscow) for numerous discussions of this theorem and Prof. Yu. M.Shirokov (Moscow) for a preciseful stimulating remark.     

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.     

Graphical solution of special kinetic differential equations

A system of homogeneous linear differential equations describes the time evolution of many dynamic systems in physics. chemistry, and biology (e.g. radioactive decay, chemical kinetics of monomolecular reactions, etc.). A graph-theory approach for the direct solution of this system represented by an acyclic reaction graph is elaborated. Applying this simple method one can construct the time-dependent solution immediately from the corresponding reaction graph.I would like to express my thanks to Drs. Z. Slanina and P. Hadrava for many helpful discussions and critical comments concerning the subject of this communication. I am greatly indebted to Prof. V. Kvasnika for all the support and understanding he has given to my work in this field.     

Investigations on laser plasma soft X-ray sources generated with low energy laser systems

Spectra of laser-induced plasmas at low laser energies and intensities (around 100 mJ and 10¹⁰ W cm^–2 respectively) have been recorded in the spectral range of 20 to 100 nm for different target materials, laser intensities at the target and laser wavelengths. For heavy target materials, a broadband spectrum with a spectral maximum typically around 30 nm is obtained. This broadband radiation source is well suited for photoionization processes and the generation of short wavelength inner-shell photoionization lasers. For the cadmium-photoionization laser, the influence of different soft X-ray spectra on the laser energy has been investigated. The potential of laser plasma soft X-ray sources for scientific and technical applications is briefly reviewed.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthday     

Optical properties of GeO2 in the ultraviolet region

The optical constants of amorphous and crystalline GeO₂ were determined by measurements of reflectivity in the region of phonon energy 0·5–25 eV and subsequent use of Kramers-Kronig analysis. The differences between the spectra of GeO₂ and those of SiO₂ are shown and discussed.The author would like to express her gratitude to Prof. J. Tauc for his interest in this work, to Dr. Z. Trousil, J. Charvát, Dr. S. Koc, Mrs. V. Míková and Dr. Németh-Sallay for the preparation of the samples, to Dr. L. ervinka and Dr. M. Rozsival for the test of their structure and to Dr. M. Závtová and Dr. I. Gregora for kind cooperation in the index-of-refraction measurements. Very useful comments by Dr, J. Sak are gratefully acknowledged.It is also a pleasure to thank Dr. R. P. Madden for discussion on the later stage of this work.     

Relativistic interactions without fields or potentials

Employing Poincaré degrees of freedomM ^jk=(¯K,¯J) andP ^k=(E,¯p) transforming linearly (but inhomogeneously) under the action of the Poincaré group we define a number of quantities which we later identify with physical observables. The identifications are consistent with the nonrelativistic limit and with other requirements following from the Poincaré covariance. Next, we treat a free relativistic particle as composed of two interacting parts. Relativistic quantum commutation relations for their Poincaré algebras and a kind of (inverse) relativistic correspondence principle are used to generate (quasi-) classical equations of their relative motion. A simple example based on these ideas is explicitly solved.I am indebted to Prof. B. Laurent, Dr. S. Flodmark, and Prof. I. Fischer-Hjalmars for pointing this out to me.     

A note on the theory of spin wave resonance in spiral structures

The appearance of two resonant modes of spin waves with different non-zero wave vectors is theoretically predicted for a magnetic arrangement of the type of an antiferromagnetic spiral combined with weak antiferromagnetism in the direction of the spiral axis. A study is made of the question of the Hamiltonian suitable for possible applications of the chosen magnetic arrangement, and the possibility of energetic stability of the considered magnetic structure for two concrete realistic forms of the Hamiltonian is pointed out.The author expresses his sincere thanks for valuable discussions and stimulating comments to Dr. S. Krupika and Dr. J. Loos, P. Novák and I. Veltruský of the Institute of Solid State Physics of the Czechoslovak Academy of Sciences, and to Assoc. Prof. J. Morkowski and Assoc. Prof. L. Kowalewski of the Polish Academy of Sciences and Poznan University.     

KrF laser system with corrected pulse front and compressed pulse duration

A high-power KrF laser system is presented providing 45 mJ, 150 fs pulses at the position of a target. Pulse front distortion is avoided by specially designed refractive optics. Pulse compression is done after final amplification using a simplified compressor.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthdayPolska Akademia Nauk, Instytut Chemii Fizycznej, Kasprzaka 44/52, PL-01-224 Warszawa, Poland