Argon (10 keV) scattered from structures,induced by bombarding a Cu(100) surface; ionization and neutralization

The ion fractions, η⁺, of 10 keV argon particles, scattered from a damaged copper surface, are measured with a time of flight spectrometer. The damage was introduced by bombardment with argon ions. The scattering angle was 30°. The results for different angles of incidence, ψ, are reported. For Ψ < 10° the ion fraction is relatively high (～27% for Ψ = 4°) and decreases as Ψ increases. For Ψ = 15° the value of η⁺ is 7%, whereas for 21° < Ψ < 27° the value of η⁺ appears to be constant (～14%). An explanation is given by assuming interatomic ionization as well as neutralization processes along the trajectory of the scattered particles. The number of step-atoms, induced by ion bombardment, is estimated to be about 2 × 10¹⁴/cm².     

Mixing transformations on metric spaces

It is proved that if a metric space is subjected to a mixing transformation, then there exists a positive numberx ₀ such that the probability that any arbitrary set of positive measure is asymptotically mapped into a set of diameter less thanx ₀ is zero. Physical implications of this result, in particular the interpretation of Poincaré recurrence, are discussed.     

Interferential microwave probe for measuring sea ripples

Summary A sea wave sensor, of new design, utilizing a teflon-coated microwave line and capable of measuring ripples up to 26 Hz is described, and its operation is analysed. Sea spectra in the short gravito-capillary domain are reported and discussed.

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Riassunto Si descrive un nuovo tipo di ondametro che utilizza una linea a microonde in filo rivestito di teflon ed è capace di misurare onde gravito-capillari fino alla frequenza di 26 Hz. Dopo aver analizzato la precisione della misura, si riportano alcuni spettri osservati in mare in regime di brezza.

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Резюме Описывается новый тип волнометра, в котором используется микроволновая линия, покрытая тефлоном и способная измерять капиллярные волны до частот 26 Гц. Анализируется точность измерений с помозью описанного микроволнового зонда. Приводятся некоторые спектры, наблюденные в море в режиме бриза.

     

Temperature dependence of the electric field gradient in CdSe and HfO2

The time differential perturbed angular correlation technique was applied to study the electric field gradient in the semiconductor CdSe and the insulator HfO₂ at different temperatures. Whereas the semiconductor CdSe shows an increasing quadrupole coupling constant with increasing temperature, the insulator HfO₂ exhibits no temperature dependence of the electric field gradient over the whole temperature range investigated.     

On the inversion of tunneling characteristics in superconductors with spin fluctuations

We have calculated the current-voltage characteristics of a superconductor with spin fluctuations explicitly included in the kernels of the Eliashberg equation along with the electron-phonon spectral density α²(ω)F(ω). These characteristics are then inverted using the method outlined by Galkin et al. to get an effective electron-phonon spectral density assuming no paramagnons are present in the Eliashberg equations during the inversion procedure. The effective electron-phonon spectral density found in this way is, to an excellent approximation, a scaling factor of $\text{1}\text{(1+λ}{}_{\mathrm{sf}}\text{)}$ times the original α²(ω)F(ω), with λ_sf the paramagnon mass renormalization.     

Capture cross-section and density of deep gap states in a−SiHx schottky barrier structures

Recombination of charge carriers in a?SiH_x Schottky barriers with density of states near mid-gap ranging from 2.8×10¹⁵?7×10¹⁶cm^-1eV^-1 is attributed to recombination centers with hole capture cross-section of 1.3×10^-15cm².     

Wheeler complexes in crystals

The basic properties of Wheeler complexes have been estimated for crystals that include positrons, positronium, electrons, holes, and excitons. Two basic forms of such quasiparticle states in crystals are considered: a) delocalized states, and b) states localized at defects. It is possible to observe Wheeler complexes by examining the annihilation characteristics of positrons in the presence of external fields such as static magnetic fields.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 10–14, April, 1981.     

Coupled bending-torsion vibrations of rotating blades of asymmetric aerofoil cross section with allowance for shear deflection and rotary inertia by use of the Reissner method

Theoretical natural frequencies and modal shapes of the first five modes of vibration are presented for a rotating blade of asymmetric aerofoil cross section, with allowance for shear deflection and rotary inertia. Frequency equations for a rotating blade with asymmetry in one plane are developed by using the Ritz process, in two ways: namely, by proceeding according to the Reissner method and according to the classical potential energy method. In both cases shape functions for the bending moment, shearing force, twisting moment, bending slope, elastic twist and deflection are developed in series form. The results obtained are compared with those existing in the literature; it is found that the Reissner method approach yields more rapid convergence than does the classical potential energy method.     

Light quarks and instantons

Instantons and anti-instantons can profoundly influence the structure of a non-Abelian gauge theory involving N flavors of massless quarks. Interactions of the quarks with these pseudoparticles can spontaneously generate a quark mass, break the theory's SU(N) × SU(N) chiral symmetry and bind quark-antiquark pairs to form N² ? 1 Goldstone bosons. If the spontaneously generated quark mass is small, multipseudoparticle configurations can be treated in a dilute gas approximation.