Stress characteristics of creep of alpha-Zr in the temperature interval 300–900 K

The stress experiments of alpha-Zr were performed within the temperature interval 300 to 900 K using the incremental loading method. The temperature interval may be divided into three regions — the low temperature region (300–475 K), the transient region (475–775 K) and the high temperature region (above 775 K). The transient region was characterized by the maximum of the strain-rate sensitivity parameterm and also the creep deformation was — to a certain degree — affected by the athermal mechanism.The authors would like to thank Professor J.adek, DrSc, for many valuable discussions, unfailing support and continual encouragement.     

Analogous negative parity spectra of125Xe and127Xe

The low spin states of the nucleus¹²⁷Xe have been investigated with the (, 2n) reaction by means of in-beam--spectroscopy, using theosiris-cube-spectrometer at the FNTandem accelerator facility of the University of Cologne. In the negative parity system, four excited states for each of the spins 11/2^–.15/2^– and two 5/2^–.9/2^– — states could be established at excitation energies up to 1MeV above the Yrast line. With this new data, we are able to compare the non-Yrast states and their decay properties to the corresponding states of¹²⁵Xe, which had been studied with similar methods in Cologne. The almost one-to-one correspondence between the states of these neighboring neutron-odd nuclei is a clear indication that their excitations at low spin remain collective well above the Yrast line.     

The temperature dependence of the refractive index of an aqueous suspension of polystyrene microspheres

We report an experimental measurement, based on an interferometric technique, for the determination of the temperature dependence of the refractive index n _L of a liquid suspension of dielectric spheres in the thermal range 20–52° C. In this range we have measured values of n _L /T of order of magnitude 10^–4° C^–1. The observed values are compared with those obtained for water.     

Far infrared properties of SbSI-SbSeI mixed crystals

Far infrared reflectivity of eight SbS_1–x Se _x I mixed single crystals was measured in 50–400 cm^–1 region in polarized light at 25 and –170 C. While the low-frequency ferroelectric mode shows clear one-mode behaviour the second B_1u mode in 126–180 cm^–1 region shows two-mode behaviour. The existence of local and gap modes in this case is discussed.The author thanks ing. K.Nejezchleb from College of Chemical Technology in Pardubice for the crystals, L.Novák for helpful discussions, Z.Híová for computations and N.Dvoáková for help and figure drawing.     

About X0 (958) spin determination

The likelihood analysis of all the production and decay information about the reaction K^–pX⁰ is suggested, instead of the one-dimensional Adair analysis. It is shown that even the analysis of the present data could yield the likelihood ratio of the 0^– and 2^– hypotheses less than 10^–5.The author is much grateful to V. I.Ogievetsky, V. I.Rud, W.Tybor and A. N.Zaslavsky for valuable discussions.     

On the interpretation of the relativistic quantum mechanics with invariant evolution parameter

The relativistic quantum mechanics with Lorentz-invariant evolution parameter and indefinite mass is a very elegant theory. But it cannot be derived by quantizing the usual classical relativity in which there is the mass-shell constraint. In this paper the classical theory is modified so that it remains Lorentz invariant, but the constraint disappears; mass is no longer fixed—it is an arbitrary constant of motion. The quantization of this unconstrained theory gives the relativistic quantum mechanics in which wave functions are localized and normalized in spacetime. Though many authors have published good works in support for such a localization in time, the latter has been generally considered as problematic. Here I show that wave packets restricted to a finite region of spacetime are not a nuisance, but just the contrary. They have the physical interpretation in the fact that an observer perceives a world line event by event, as his experience of now proceeds in spacetime. Quantum mechanically this means that at a certain value of the evolution parameter the event is most probably to occur within the spacetime region around {ie1005-1} occupied by the wave packet; at later value of the position {ie1005-2}—and hence the time coordinate t—of the wave packet is changed. This is closely related to the interpretation of quantum mechanics in general.     

A laboratory test of Mach's principle and strong-field relativistic gravity

A laboratory experiment that tests the validity of Mach's principle — the relativity and gravitational induction of inertia — and relativistic gravity in strong-field circumstances is described. It consists of looking for a stationary shift in the apparent weight of an object when a transient mass fluctuation is induced in one of its parts, that part then being subjected to a pulsed thrust. The transient mass fluctuation induced is of the order of a few tens of milligrams, and the stationary weight shift observed is several milligrams. Details of the apparatus used (capable of detecting an effect at the level of about a tenth of a milligram) are presented. Procedural protocols are laid out. The results obtained — signals some 10 to 15 times the standard error in magnitude — confirm to better than order of magnitude that the predicted effect is indeed present. The consequences of this confirmation of Mach's principle and relativistic gravity are briefly addressed. In particular, it is pointed out that in light of these results radical timelessness seems to be the correct way to understand reality and, from the practical point-of-view, it may prove possible to make traversable wormholes whenever we choose to devote sufficient resources to that end.     

Quantum theoretical physics is statistical and relativistic. II

The vanishing divergence of 4-velocity, crucial to our theoretical basis for a classical statistical quantum mechanics, is investigated further. We demonstrate that this property of 4-velocity is of purely relativistic—kinematic origin. So, unlike our treatment in the initial work, we need not constrain the environment to that of electromagnetism; a superior argument results by the analog of a relativistic particle's world line with fixed curves in a Euclidean 3-space, such that ·v=0 iff (v)²=–1!     

Compression properties of finite nuclei in a semi-classical relativistic approach

Skyrme type potentials are known to lead — in the framework of the scaling model — to a finite-nucleus incompressibility valueK _A where the volume coefficientK _v equals roughly the negative surface coefficient K_s. This is found for Skyrme interactions with K_v between 200 and 360 MeV. In a semi-classical relativistic approach on the basis of the — model (linear as well as non-linear) using in addition local density approximations, we findK _s to depend in particular on the surface energy coefficienta _s , and not so much on the value ofK _v . For a realistic value of a_s, both the linear and the non-linear — model (with NL1 parameter set) yield a ratio ¦K _s K _v ¦ of approximately 1. We discuss implications of this finding with a particular view on recent empirical results onK _v andK _s .Dedicated to Prof. Dr. H. J. Mang on the occasion of his 60th birthday     

Solving the Gross-Neveu model with relativistic many-body methods

The Gross-Neveu model provides a unique opportunity to apply relativistic many-body techniques (Dirac-Hartree approximation, RPA) in a context where all calculations can be done analytically and — in the largeN limit — yield the exact results. The physical fermion as well as multifermion (baryon) and fermion-antifermion (meson) bound states are discussed in this spirit, with special emphasis on the role of the Dirac sea.Supported by the Bundesministerium für Forschung und Technologie     

Geometrical scaling and analyticity of scattering amplitudes

Geometrical scaling connects, att=0, the phase of the Pomeron amplitudeF(s, t) to that of its derivativeF(s, t)/t. This intrinsic phase correlation allows one to derive a dispersive sum rule which strongly relates the high- and low-energy regions.Presented at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.Thanks are due to D.Robertson and J.Dias de Deus for useful discussions.     

Interferometric measurement of plasma density in the range 1019–1022 m−3

A laser interferometer, operating at the wavelength =0·337 mm suitable for the plasma density measurements in the range 10¹⁹–10²² m^–3 as well as a simple construction of the HCN laser are described.The authors wish to thank Dr. P.unka for fruitful discussions and Dr. J.Musil for the design and construction of the detector.     

High-frequency sum-rules for classical relativistic plasmas in a magnetic field

High-frequency sum rules for the transverse elements of classical relativistic plasmas in a magnetic field are derived. The relativistic effect reduces the plasma mode frequency by a factor of ^–1(1 –v²/3c².     

Electronic excitation spectrum of an antiferromagnetic semiconductor (EuTe)

We study the electronic quasiparticle spectrum of an antiferromagnetic semiconductor, with a special application to EuTe. By use of the commonly accepteds-f model it is shown that the conduction band splits into two quasiparticle subbands, where this splitting persists in the paramagnetic region (T>T _n ), too. Shape, width and degree of overlapping of the two subbands are strongly temperature dependent and quite different for different types off-spin arrangements.—We present furthermore a critical classification of mean field treatments (Zener model), which neglect all spin exchange processes between conduction electrons and localized moments. Within our many body approach the lower conduction band edge of EuTe does not shift significantly with temperature, in agreement with the experiment, while the Zener model predicts a drastic red shift upon cooling belowT _n .     

On path integrals and relativistic quantum mechanics

A proposal for formulation of relativistic quantum mechanics in terms of path integrals is presented.We are deeply indebted to Dr. M.Petrá for many stimulating discussions.     

Microwave heating of electrons of a dense plasma column at frequencies higher than electron cyclotron frequency

In this experimental study the absorption of plasma waves, excited in a dense plasma column, was investigated and the localization of the regions of efficient heating of electrons were determined in a broad range of parameters: 1>_ce/>0·1, 0·3<n/n _UH <25, 10^–5<v/< <10^–3. The heating of electrons near the second electron cyclotron harmonic was investigated in greater detail.We are grateful to the members of the Staff of the Institute of Plasma Physics Drs. P.unka, R.Klí'ma, V.Kopecký, J.Musil for discussion of the results. We also thank Drs. J.Musil, F.áek for the help and advice in the early stages of experimental work during construction of different diagnostic devices. Our thanks are due to the director of the Institute Dr. J.Váa for encouraging support of this experimental program.     

Mode competition of the gyrotron under high efficiency operating conditions

Conclusion Mode competition — interaction between a mode and another mode — is due to the non-linearity of the relativisitc factor . At the beginning of a multimode oscillating, the behavior of the multimode oscillating is only dependent on the ratio of mode frequency and relativistic cyclotron frequency and is in agreement with that described by single mode theory. In non-linear domain mode interaction depends on both amplitudes of A₁ and A₂ and phase difference _i of the two modes. The main effect of mode interaction is that excitation of the parasitic mode suppresses growth of the operating mode.Under the operating conditions with high efficiencies, a mode interaction between the dominant mode and the lower lateral mode is almost unavoidable, especially in the gyrotron operating with a cavity at higher order modes to increase the capability of output power.A research fellow of the Alexander von Humboldt Foundation coming from Beijing Vacuum Electron Devices Research Institute, Beijing, China     

Measurements of π+p,K+p and pp elastic scattering)

The paper presents the results on differential cross sections for elastic scattering of 7⁺-, K⁺-mesons and protons on protons in the 4-momentum transfer squared range 0·08 ¦t¦ 1·0 (GeV/c)² and incident particle momentum of 29 and 43 GeV/c for pions and kaons and 29, 43, 50 and 65 GeV/c for protons. The measurements were taken with the spectrometer Sigma, installed in the positive beam of the IHEP accelerator.Presented by F. A. Yotch at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975.The authors would like to express their gratitude to A. A.Logunov, Yu. D.Prokoshkin, L. D.Soloviev and V. A.Yarba for their support of this experiment. We are indebted to CERN Administration for giving us a permission to use a part of equipment of the CIBS spectrometer and to W.Kienzle for useful discussions.     

Radiation by relativistic dipoles. II

In a continuation of an earlier study, the electromagnetic fields of a point magnetic moment — a magneton — in uniform rectilinear motion, with a given spin precession, are analyzed. It is shown that the same equations can be found through Lorentz transformations from the corresponding expressions in the rest frame. The relationship between the electric and magnetic fieldsE andH radiated by a point magnetic dipole moment and a point electric dipole moment is derived through the use of dual transformations of the electromagnetic field tensor. It is assumed that each moment is in relativistic and otherwise arbitrary motion. In the relativistic case, as in the nonrelativistic case, the switch is accompanied by the replacementsHE, E-H. A covariant formalism is developed for describing the electromagnetic fields in the wave zone. The electromagnetic field tensor associated with the radiation is analyzed.V. V. Kuibyshev Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 73–78, March, 1993.     

Photon-photon luminosities in relativistic heavy ion collisions at LHC energies

Effective – luminosities are calculated for various realistic hadron collider scenarios. The main characteristics of photon-photon processes at relativistic heavy-ion colliders are established and compared to the corresponding –-luminosities ate ⁺-e ^– — and future photon linear colliders (PLC). Higher order corrections as well as inelastic processes are discussed. It is concluded that feasible high luminosity Ca–Ca collisions at the Large Hadron Collider (LHC) are an interesting option for – physics up to about 100 GeV – CM energy.