Faculty of Physics
M.V.Lomonosov Moscow State University
Physics of nuclei and elementary particles

## Giant dipole resonance in heavy deformed nuclei

### B.S. Ishkhanov$^{1,2}$, S.Yu. Troshchiev$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 325

Analysis of all the experimental data on nuclear shape deformation and photonuclear reaction cross sections in the energy range of giant dipole resonance is performed. The relationship between the giant resonance width and the nuclear-quadrupole-deformation parameter value is shown.

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Theoretical and mathematical physics

## Internal vibration energy in polyatomic molecules containing chains of identical biatomic dipoles

### V.V. Komarov$^1$, A.M. Popova$^1$, L. Schmidt$^2$, H. Jungclas$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 338

The quantum processes of excitation and vibrational energy transport that occur in polyatomic organic molecules under IR radiation are analyzed. The polyatomic organic molecules considered contain substructures with finite numbers of identical biatomic valence bonds, which play the role of antennas that trap and accumulate IR radiation. The result of this analysis can be used for determining the sequences of amino-acid residues in oligopeptides.

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## Extension of Haag’s theorem in the case of the lorentz invariant noncommunitative quantum field theory in a space with arbitrary dimension

### K.V. Antipin$^1$, Yu.S. Vernov$^{1,2}$, M.N. Mnatsakanova$^3$

Moscow University Physics Bulletin 2011. 66. N 4. P. 349

The generalized Haag theorem was proven in $SO(1,k)$ invariant quantum field theory. Apart from the $(k{+}1)$ variables, an arbitrary number of additional coordinates, including noncommutative ones, can occur in the theory. In $SO(1,k)$ invariant theory new corollaries of the generalized Haag theorem are obtained. It has been proven that the equality of four-point Wightman functions in the two theories leads to the equality of elastic scattering amplitudes and thus to the equality of the total cross sections in these theories. It was also shown that at $k > 3$ the equality of $(k{+}1)$ point Wightman functions in the two theories leads to the equality of the scattering amplitudes of some inelastic processes. In the $SO(1,1)$ invariant theory it was proven that if in one of the theories under consideration the $S$-matrix is equal to unity, then in another theory the $S$-matrix equals unity as well.

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## Magnetization reversal of small particles in an oscillating magnetic field

### D.V. Vagin$^{1,2}$, O.P. Polyakov$^1$

Moscow University Physics Bulletin 2011. 66. N 4. P. 354

The nonlinear behavior of single spherical particles and many-particle ensembles under an external oscillating magnetic field was studied using the Landau-Lifshitz-Gilbert approach. The exact analytical formulae for calculating field frequency and the dependence of the configuration of the initial moment on the system mean magnetization were obtained. Using asymptotic decomposition we obtained simple expressions for describing the nonlinear dynamics of spherical particles in the cases of large and small frequencies. These solutions are in good agreement with numerical calculations of the Landau-Lifshitz-Gilbert equation for the considering systems.

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Condensed matter physics

## On the theory of the molecular states of $A^{+}$-centers in semiconductor quantum wells

### V.Ch. Zhukovsky$^1$, V.D. Krevchik$^2$, A.V. Levashov$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 343

The spectra of photoluminescence in the GaAs/AlGaAs quantum wells with $A_2^{+}$-centers are calculated within the model of the zero radius potential. It is shown that the model of $A_2^{+}$-centers can adequately describe the experimental data that point to the existence of molecular states of$A^{+}$-centers in 2D GaAs/AlGaAs structures.

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## Diffuse X-ray scattering by ice in the vicinity of the melting point

### V.M. Silonov$^1$, V.V. Chubarov$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 369

The X-ray pattern of ice recorded at −10°C reveals, along with the reflexes of a hexagonal phase, intense diffuse X-ray scattering, testifying to the presence of a noncrystalline phase in the sample. Heating of ice to a temperature close to the melting point leads to almost complete decomposition of the crystalline phase. As this takes place, intense diffuse X-ray scattering with a maximum at $2\Theta$ of 23°C appears in the diffraction pattern, which is typical for a metastable amorphous phase. The first maximums of the radial distribution function for the metastable amorphous phase of ice appear to be close in their positions to the first radii of the hexagonal phase coordination spheres.

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## Structural ordering and self-organization effects in multilayer Pd/Fe films

### V.A. Gordienko$^1$, M.V. Starkova$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 375

The structural features of the distribution of Pd and Fe atoms in multilayer films derived via Penning-discharge sputtering are studied. The preparation of films is a highly nonequilibrium process; at the same time, it is relatively simple in terms of possible structural implementations, which are shown during the self-organization of sputtered atoms through the formation of clusters with an individual ordered structure. It is important that the “dynamic chaos” that appears during sputtering is stabilized during crystallization, which makes it possible to study the resulting structures using nondestructive inspection methods with fairly wide possibilities. Therefore, it is of interest to study self-organization during the sputtering of multilayer films in order to reveal the mechanisms of cluster formation and to simulate them. It is also shown that the self-organization during sputtering and subsequent crystallization is accompanied not only by the ordering in the form of clusters, buts also by an ordered arrangement of these clusters.

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## Bimodal size-distribution function in a nanoparticle ensemble formed during the laser irradiation of the surfaces of solids

### V.I. Emel’yanov

Moscow University Physics Bulletin 2011. 66. N 4. P. 383

A defect-deformational (DD) model of the formation of a nanoparticle ensemble on the surface of solids under multipulse laser ablation is developed. The DD theory of bimodal nanoparticle size distribution is developed, which expresses size distribution via the bimodal growth rate of DD surface gratings generated by laser irradiation. The obtained size-distribution function corresponds to the experimental data.

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Physics of nuclei and elementary particles

## Signals in the underground scintillation detectors of the Yakutsk array from muons of extensive air showers

### L.G. Dedenko$^1$, T.M. Roganova$^2$, G.F. Fedorova$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 358

A model of the underground part of the Yakutsk array was developed. The signals from muon scintillation detectors were calculated using the GEANT4 code within this model. It was shown that the signals strongly fluctuate and may be several times higher that the mean ionization energy losses by a single muon. These large losses imitate high muon multiplicity in the case of a low muon density. It was also shown that there are many gamma particles near the shower axis, which significantly contribute to signals in underground detectors and thus make data interpretation difficult.

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## Measuring nuclear reaction yields in a procedure based on decay chain analysis

### S.S. Belyshev$^1$, K.A. Stopani$^2$, S.Yu. Troschiev$^1$, A.S. Kurilik$^1$, A.A. Kuznetsov$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 363

The problem of finding nuclear reaction yields in activation experiments is analyzed. It was shown that in the presence of complex decay chains the activity of gamma-spectrum lines of the nuclei can be described with a linear statistical model. Since the covariance matrix is unavailable the iteratively reweighted general least squares method is an appropriate means of obtaining a maximum-likelihood estimation. The relationship between the variances of estimated yields and the duration of spectrum measurements is discussed.

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Chemical physics, physical kinetics, and plasma physics

## Electrohydrodynamic peculiarities of corona discharge interaction with a liquid surface

### A.F. Aleksandrov, V.L. Bychkov, D.V. Bychkov, S.A. Volkov, A.A. Kostyuk, V.A. Chernikov

Moscow University Physics Bulletin 2011. 66. N 4. P. 390

This study was devoted to experimental investigations of a corona discharge over the surface of the following liquids: tap and distilled water, alcohol, glycerin, and mixtures of alcohol with water and glycerin. One of the electrodes was placed over the liquid surface, while another one was submerged in it. Three modes of discharge over the liquid surface were obtained, namely an ordinary corona, an intermediate mode, and an arc discharge mode. In these modes, a funnel-shaped deepening, jets, and scattered jets directed toward the upper electrode were observed on the liquid surface under the action of the discharge. A qualitative mode of funnel formation on the liquid surface under the influence of an ionic wind induced by a corona discharge was presented. The formation of jets and scattered jets was related to the development of Tonks-Frenkel and Rayleigh instabilities.

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Physics of Earth, atmosphere, and hydrosphere

## The global average rise in sea level and the rises of the Northern and Southern Hemisphere average sea levels in the present epoch

### Yu.V. Barkin

Moscow University Physics Bulletin 2011. 66. N 4. P. 398

The mechanisms for the increase in the global average sea level in the present epoch are studied. The phenomenon of contrasting secular Southern and Northern Hemisphere average sea-level changes is explained; this phenomenon was predicted earlier by the author on the basis of the observed secular northward trend of the Earth’s center of mass at a rate of 5–6 mm/yr. Studies of sea-level changes using altimetry method are criticized.

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Physics of nuclei and elementary particles

## The role of daughter nuclei excitation in a structure of photonuclear resonances

### N.G. Goncharova$^1$, N.E. Mashutikov$^2$

Moscow University Physics Bulletin 2011. 66. N 4. P. 407

The results of microscopic calculations of dipole resonances in $^{32}$S and $^{34}$S nuclei obtained on the basis of a “particle-finite nucleus state” using the spectroscopic factors of a nucleon pick-up reaction are presented. The conditions for the applicability of this approach to obtaining a realistic picture of a photo-excitation cross section are discussed.

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