The research program of the Liquid Scintillation Detector (LSD) in the Mont Blanc Laboratory

A massive (90 tons) liquid scintillation detector (LSD) has been running since October 1984 in the Mont Blanc Laboratory at a depth of 5,200 hg/sq cm of standard rock. The research program of the experiment covers a variety of topics in particle physics and astrophysics. The performance of the detector, the main fields of research are presented and the preliminary results are discussed

Global Spiral Modes in NGC 1566: Observations and Theory

We present an observational and theoretical study of the spiral structure in galaxy NGC 1566. A digitized image of NGC 1566 in I-band was used for measurements of the radial dependence of amplitude variations in the spiral arms. We use the known velocity dispersion in the disk of NGC 1566, together with its rotation curve, to construct linear and 2D nonlinear simulations which are then compared with observations. A two-armed spiral is the most unstable linear global mode in the disk of NGC 1566. The nonlinear simulations are in agreement with the results of the linear modal analysis, and the theoretical surface amplitude and the velocity residual variations across the spiral arms are in qualitative agreement with the observations. The spiral arms found in the linear and nonlinear simulations are considerably shorter than those observed in the disk of NGC 1566. We argue therefore, that the surface density distribution in the disk of the galaxy NGC 1566 was different in the past, when spiral structure in NGC 1566 was linearly growing.Comment: 41 pages, 20 figures, to be published in the Astrophysical Journa

Chemical Abundance Gradients in the Star-Forming Ring Galaxies

Ring waves of star formation, propagating outwardly in the galactic disks, leave chemical abundance gradients in their wakes. We show that the relative [Fe/O] abundance gradients in ring galaxies can be used as a tool for determining the role of the SNIa explosions in their chemical enrichment. We consider two mechanisms which can create outwardly propagating star forming rings in a purely gaseous disk -- a self-induced wave and a density wave, and demonstrate that the radial distribution of the relative [Fe/O] abundance gradients does not depend on the particular mechanism of the wave formation or on the parameters of the star-forming process. We show that the [Fe/O] profile is determined by the velocity of the wave, initial mass function, and the initial chemical composition of the star-forming gas. If the role of SNIa explosions is negligible in the chemical enrichment, the ratio [Fe/O] remains constant throughout the galactic disk with a steep gradient at the wave front. If SNIa stars are important in the production of cosmic iron, the [Fe/O] ratio has gradient in the wake of the star-forming wave with the value depending on the frequency of SNIa explosions.Comment: Uses aas2pp4.sty and epsfig.sty, 7 pages including one figure To appear in Astrophysical Journa

Chemical Evolution of the Galaxy Based on the Oscillatory Star Formation History

We model the star formation history (SFH) and the chemical evolution of the Galactic disk by combining an infall model and a limit-cycle model of the interstellar medium (ISM). Recent observations have shown that the SFH of the Galactic disk violently variates or oscillates. We model the oscillatory SFH based on the limit-cycle behavior of the fractional masses of three components of the ISM. The observed period of the oscillation ($\sim 1$ Gyr) is reproduced within the natural parameter range. This means that we can interpret the oscillatory SFH as the limit-cycle behavior of the ISM. We then test the chemical evolution of stars and gas in the framework of the limit-cycle model, since the oscillatory behavior of the SFH may cause an oscillatory evolution of the metallicity. We find however that the oscillatory behavior of metallicity is not prominent because the metallicity reflects the past integrated SFH. This indicates that the metallicity cannot be used to distinguish an oscillatory SFH from one without oscillations.Comment: 21 pages LaTeX, to appear in Ap

Dynamics of Gaseous Disks in a Non-axisymmetric Dark Halo

The dynamics of a galactic disk in a non-axisymmetric (triaxial) dark halo is studied in detail using high-resolution, numerical, hydrodynamical models. A long-lived, two-armed spiral pattern is generated for a wide range of parameters. The spiral structure is global, and the number of turns can be two or three, depending on the model parameters. The morphology and kinematics of the spiral pattern are studied as functions of the halo and disk parameters. The spiral structure rotates slowly, and its angular velocity varies quasi-periodically. Models with differing relative halo masses, halo semi-axis ratios, distributions of matter in the disk, Mach numbers in the gaseous component, and angular rotational velocities of their halos are considered.Comment: 22 pages, 11 figure

Velocity Shear of the Thick Disk from SPM3 Proper Motions at the South Galactic Pole

The kinematical properties of the Galactic Thick Disk are studied using absolute proper motions from the SPM3 Catalog and 2MASS near-infrared photometry for a sample of ~1200 red giants in the direction of the South Galactic Pole. The photometrically-selected sample is dominated by Thick Disk stars, as indicated by the number-density distribution that varies with distance from the Galactic plane as a single-valued exponential over the range 1<z<4 kpc. The inferred scale height of the Thick Disk is 0.783 +/- 0.048 kpc. The kinematics of the sample are also consistent with disk-like motion. The U-velocity component is roughly constant, reflecting the Sun's peculiar motion, while a considerable shear is seen in the mean rotational velocity, V. The V-velocity profile's dependence on z is linear, with a gradient of dV/dz = -30 +/- 3 km/s/kpc. The velocity dispersions, in both U and V, show a lesser gradient of about 9 +/- 3 km/s/kpc. We demonstrate that the derived velocity and velocity-dispersion profiles are consistent with the assumptions of dynamical equilibrium and reasonable models of the overall Galactic potential.Comment: 38 pages, 9 figures, accepted for publication in A

Направления актуализации сметных норм в транспортном строительстве

For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version). ABSTRACT The wide range of conditions for performance of works in transport construction sector traditionally should meet high demands on the methodology for their accounting when calculating the estimated cost. In its current state, the national (federal) budget and regulatory framework is a compromise, especially when it comes to adjusting the costs in different circumstances of natural, climatic, different regional resources, transport accessibility. The article reveals the problem of the sectoral specificity of the use of labor resources at the objects of construction of the railway transport infrastructure. An example of the impact of typical working conditions on quantitative regulatory parameters is given as a calculation and methodical variant of solving economic problems. Keywords: economy, transport construction, norms, estimated cost, analysis, labor intensity, production conditions, coefficients, factors.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии). Широта спектра условий производства работ в транспортном строительстве традиционно предъявляет высокие требования к методологии их учёта при расчёте сметной стоимости. В текущем своём состоянии национальная (федеральная) сметно-нормативная база является компромиссной, особенно когда это касается корректировки затрат в разных обстоятельствах природных, климатических, отличных друг от друга региональных ресурсов, транспортной доступности. Статья раскрывает проблему отраслевой специфики использования трудовых ресурсов на объектах строительства инфраструктуры железнодорожного транспорта. В качестве расчётно-методического варианта решения экономических задач приведён пример воздействия типичных условий производства работ на количественные нормативные параметры

K^+ production in the reaction 58Ni+58Ni^{58}Ni+^{58}Ni at incident energies from 1 to 2 AGeV

Semi-inclusive triple differential multiplicity distributions of positively charged kaons have been measured over a wide range in rapidity and transverse mass for central collisions of $^{58}$Ni with $^{58}$Ni nuclei. The transverse mass ($m_t$) spectra have been studied as a function of rapidity at a beam energy 1.93 AGeV. The $m_t$ distributions of K^+ mesons are well described by a single Boltzmann-type function. The spectral slopes are similar to that of the protons indicating that rescattering plays a significant role in the propagation of the kaon. Multiplicity densities have been obtained as a function of rapidity by extrapolating the Boltzmann-type fits to the measured distributions over the remaining phase space. The total K^+ meson yield has been determined at beam energies of 1.06, 1.45, and 1.93 AGeV, and is presented in comparison to existing data. The low total yield indicates that the K^+ meson can not be explained within a hadro-chemical equilibrium scenario, therefore indicating that the yield does remain sensitive to effects related to its production processes such as the equation of state of nuclear matter and/or modifications to the K^+ dispersion relation.Comment: 24 pages Latex (elsart) 7 PS figures to be submitted to Nucl. Phys

Control of star formation by supersonic turbulence

Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (ABSTRACT ABBREVIATED)Comment: Invited review for "Reviews of Modern Physics", 87 pages including 28 figures, in pres

Field induced single ion magnet based on a quasi octahedral Co ii complex with mixed sulfur oxygen coordination environment

Synthesis and characterization of structure and magnetic properties of the quasi octahedral complex pipH2 [Co TDA 2] 2H2O I , pipH22 piperazine dication, TDA2 amp; 8722; thiodiacetic anion are described. X ray diffraction studies reveal the first coordination sphere of the Co II ion, consisting of two chelating tridentate TDA ligands with a mixed sulfur oxygen strongly elongated octahedral coordination environment. SQUID magnetometry, frequency domain Fourier transform FD FT THz EPR spectroscopy, and high level ab initio SA CASSCF NEVPT2 quantum chemical calculations reveal a strong easy plane type magnetic anisotropy D amp; 8776; 54 cm amp; 8722;1 of complex I. The complex shows field induced slow relaxation of magnetization at an applied DC field of 1000 O