The interaction of foils activated by thermal neutrons

The interaction of foils lying in a plane during their activation by thermal neutrons has been calculated. Numerical values of functions are listed, which can be used in calculations, especially for graphite. The interaction was measured in the graphite column of the VVR-S reactor.

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, , . , , . VVR-S.

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We thank J. Frytacký, T. Kania and V. ervenka for their help in the numerical calculations and measurements.     

The effect of the orientation of zinc single crystals and of the rate of growth on the direction of cell substructure

The effect of the orientation of zinc single crystals and the rate of growth on the direction of the formation of cellular substructure is observed. A model accounting for the observed dependences is proposed.

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One massless particle equals two Dirac singletons

The remarkable representations of the 3+2 de Sitter group, discovered by Dirac, later called singleton representations and here denoted Di and Rac, are shown to possess the following truly remarkable property: Each of the direct products Di Di, Di Rac, and Rac Rac decomposes into a direct sum of unitary, irreducible representations, each of which admits an extension to a unitary, irreducible representation of the conformal group SO(4, 2). Therefore, in de Sitter space, every state of a free, massless particle may be interpreted as a state of two free singletons — and vice versa. The term massless is associated with a set of particle-like representations of SO(3, 2) that, besides the noted conformal extension, exhibit other phenomena typical of masslessness, especially gauge invariance.     

Level shift of μ mesoatoms and anomalous interaction of muons with nuclei

The effect of the possible anomalous interaction of a muon with nuclei, due to exchange of the muon and the nucleon, with vector V=⁰, , , J/, , and ⁰ mesons, on the level of the mesoatoms is considered. An estimate is carried out of the energy shift of the 2P-1S transition. A comparison of the estimates obtained for the 2P-1S transition energy shift in the mesoatom²⁰⁶Pb with the experimental data does not contradict the presence in the muon of an anomalous interaction with the nucleon, defined by the effective coupling constant /4 4·10^–4.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 75–80, June, 1978.     

Instability in degenerate two-photon running wave laser with detuning

The previous stability analysis of the degenerate two-photon running wave laser is extended to the inclusion of detuning between frequencies of cavity and atoms. We derive the analytical equation for the critical pumping and prove analytically that for the special case ofr (/) being unity, there is no Hopf bifurcation instability for the bad cavity. The good cavity case is analysed numerically. The role played by detuning is to raise the critical pumping. In the case ofk (or <K) where there is no Hopf bifurcation instability for the perfect tuning case, the large detuning can give rise to self-pulsing instability.     

Late-time behavior of primordial gravitational waves in expanding universe

The results of two different approaches to the late-time behavior of primordial gravitational radiation are compared. Using asymptotic expansion in time of the tetrad components of the Riemann tensor one finds that initially chaotic behavior transfers itself into a radiative gravitational field of Petrov typeN ast. On the other hand, to accomplish the physical picture, we study the high-frequency behavior of the field variables in the same formalism. We show that the background spacetime is of general Petrov type I, and then calculate the tetrad components of the stress-energy tensor induced by the disappeared radiation with the help of Newman-Penrose equations.     

Explicit Finitism

This paper takes the first steps in developing a theory of explicit finitism which puts explicit limits on the size of finite objects. We provide motivation in the physics of computation sense, survey some of the difficulties and describe the appropriate computing machinery. We introduce the subset J of the real numbers that is the central mathematical object emerging from considerations of explicit finitism, and take the first steps in studying its properties.     

Inclusive φ meson production in neutron–carbon interactions at 20–70 GeV

mesons have been reconstructed from their decay to positive and negative kaons, using the data obtained from interaction of neutrons at 20–70 GeV with a carbon target collected by EXCHARM experiment at the Serpukhov accelerator. The analysis relies on the use of reconstructing trajectories and particle identification. From about 45 million events (19600 ± 350) mesons were found. The meson mass is measured to be (1019.4 ± 0.1)MeV/c ²; the meson width is measured to be (4.9 ± 0.3)MeV/c ². The investigation has been performed at the Joint Institute for Nuclear Research at the Laboratory of Super High Energies.     

A new theory on scattering of electrons due to spiral dislocations

The topologically singular lattice structure around a spiral dislocation scatters electrons in a manner much different from the deformation-potential-scattering. Thet-matrix is represented ast(k, k)=t ₀ sin (k _z/2) exp (±i _kk/2)/sin ( _kk/2) with the scattering angle _kk, the componentk _z of the wave vector parallel to the dislocation, andt ₀(Fermi energy). This kind of scattering alone does not cause a perpendicular resistivity, but in a dirty limit a specific dislocation resistivity does exist, whose relaxation time per unit length of dislocation is of the order of/(Fermi energy).Work performed within the research program of the Sonderforschungsbereich 125 Aachen-Jülich-KölnOn leave of absence from Department of Materials Science, Hiroshima University, Higashisenda-machi, Hiroshima, Japan