This book presents the main mathematical methods of description and general problems in the theory of linear waves in dispersive systems and media, including equilibrium and nonequilibrium waves. To ...show how the general theory can be applied in practice, the authors give a unified description of the waves in all important physical systems which are traditionally studied in the mechanics of continuous media, electrodynamics, plasma physics, electronics and physical kinetics. Consideration is also given to the interaction of waves in coupled systems, the propagation and evolution of localized wave perturbations, and the emission of waves from dispersive media under the action of external sources moving in a prescribed manner. A general theory of instabilities of linear systems is given, in which the criteria for absolute and convective instabilities are formulated and compared, and Green's functions for some nonequilibrium media are calculated. Special attention is paid to problems in the theory of linear electromagnetic waves in plasmas and plasma-like media. The book also contains a number of original results of the present-day wave theory that have thus far been published in scientific journals only.
Investigation of double beta decay processes (β+EC, EC/EC) of 58Ni was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.). A sample of natural nickel, containing ∼68% of 58Ni ...and a mass of ∼21.7 kg, was measured using ultra low-background HPGe detector Obelix (sensitive volume of 600 cm3) during ∼143.8 days. New experimental limits on 2νβ+EC decay of 58Ni to the ground 0+ and (math), 811 keV excited state of 58Fe, and 2νEC/EC decay of 58Ni to (math), 811 keV and (maht), 1 675 keV excited states of 58Fe were obtained in this measurement. There are -T1/2(β+EC, 0+ → 0+) > 1.7 × 1022 y; (math), (math), (math). For resonant neutrino-less radiative EC/EC decay with energy of 1 918.3 keV a new experimental limit of T1/2 (0νEC/EC - res, 1918KeV) > 4.1 ×1022 y was also obtained. All limits are at 90 % CL.
We consider the possibility of the formation of a superconductivity state either in a semiconductor or in an electron–hole plasma with degenerate electrons due to the attractive forces between the ...electrons as a result of the exchange effects through the electron–hole sound wave by an analogy to the phonon waves in a solid state. We have determined an interaction potential between two electrons in a degenerate electron–hole plasma. The potential appears to be attractive at distances much larger than the Debye radius and decreases as 1/r3. We discuss the conditions in which the bound electron state, the so‐called “Cooper Pair,” in a such field can be formed.
Searching for the β+EC and EC/EC Decays of 74Se Rukhadze, N. I.; Barabash, A. S.; Brudanin, V. B. ...
Bulletin of the Russian Academy of Sciences. Physics,
08/2020, Letnik:
84, Številka:
8
Journal Article
Recenzirano
Double beta decay (β
+
EC, EC/EC) of
74
Se was investigated at the Modane underground laboratory (LSM, France; 4800 m of water equivalent) using the OBELIX ultralow-background HPGe detector with a ...sensitive volume of 600 cm
3
and a sample of natural selenium with a mass of 1.6 kg containing ~0.89% (~14.24 g) of
74
Se. The new experimental limits for β
+
EC and EC/EC decays of
74
Se to ground 0
+
and excited
596 keV, and
1204 keV states of
74
Ge, were obtained from experimental data accumulated over 135 days.
The authors' view on the development of theoretical concepts of collisionless plasma is presented. The review begins with studies by Lord Rayleigh, who established the basics of multi-electron system ...theory in 1906 as a development of J J Thompson's atomic theory. His study was based on the concept that electrons move in a self-consistent electric field produced by the electrons themselves. Rayleigh then used this concept to predict the oscillatory motion of electrons and obtained a formula for the frequency of a system's collective oscillations. Those studies established a foundation for Rayleigh's model of a multi-electron system, and his formula for the frequency of collective oscillations may be considered the first analytical result of the science pioneered by Lord Rayleigh.
The double beta decay ( beta beta ) is very challenging subject of today's physics. It can be used as a powerful tool to test neutrino properties (e.g. Dirac or Majorana type of neutrino) and lepton ...number conservation. However, these experiments demand very high sensitivity and very strong background reduction. We have been performing intensive R&D towards the use of pixel detector Timepix in the beta beta decay experiments. The Timepix device, operated in Time Over Threshold (TOT) mode, provides spectroscopic capabilities in each individual pixel. The main advantage of such detector is its ability to identify and reject background signals (e.g. tracks made by electrons, alpha particles, muons). It would efficiently recognize the signal of beta beta decay processes. Two pixel detectors, Si (pixel size 55 x 55 mu m super(2)) and CdTe (pixel size 110 x 110 mu m super(2)), were tested in the surface laboratory as well as in the underground laboratories, from the point of view of intrinsic background and the results are presented. Low background materials for construction of the setup were also identified. The first prototype of Silicon Pixel Telescope (SPT) has been tested and future improvements are also presented.
Two rather closely analogous classes of phenomena - plasma and hydrodynamic - are reviewed. Topics covered include: surface waves in an inhomogeneous plasma layer and in an inhomogeneous ...incompressible fluid flow; the instability of the tangential discontinuity of an inhomogeneous gas flow and the negative mass instability of an electron-beam-carrying plasma; radiative Cherenkov instabilities of an electron beam in a plasma and of a gas flow in a gas; the instability of plasma flows and of incompressible fluid flows with inhomogeneous velocity profiles. Special attention is given to the collisionless damping of plasma surface waves. It is shown that no such damping occurs for surface waves in gas flows.
The frequently used Maxwell's equations that contain E, B, D, and H fields are only substantiated in the framework of linear material equations and for isotropic media alone. We have shown that ...accounting for the deviation of magnetic permittivity μ (ω) from unity in the usually employed dispersion equation implies a false precision. Therefore, if spatial dispersion is disregarded, transverse waves only exist in the energy region where ε(ω) > 0 and have a positive group velocity.
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