Ferromagnetic Detectors of Axions in RF (S - X) Band

The (pseudo) Goldstone bosons arise naturally in many modern theories such as supergravity, superstring theory and variants of general relativity with torsion. By the other hand, there are well known indications that a large part of the Universe mass exists in a form of dark matter. The most attractive model of the dark matter is non-relativistic gas of the light elementary particles weakly interacting with the "usual" matter \cite{b2} - \cite{b4}. We describe ferromagnetic detectors, for search of arion(axion), where a high-sensitive two-channel SHF receiver is used. Its sensitivity reaches to $10^{-20}\,Wt$, with time of accumulation $1-10\,s$. Fourier analysis of signal provides a survey in zone up to $\pm50\,KHz$ with spectral resolution $0.1 - 25\, Hz$. There was applied a high sensitive SHF receiver based on a special computer method of coherent accumulation of signals. It is possible to use the receiver in other precise experiments: measuring of electron/positron beams polarization in storage rings, investigation of parity violation, investigation of atmosphere with radars etc.Comment: 6 pages, LaTeX, no figure

Effect of Dust Evaporation and Thermal Instability on Temperature Distribution in a Protoplanetary Disk

The thermal instability of accretion disks is widely used to explain the activity of cataclysmic variables, but its development in protoplanetary disks has been studied in less detail. We present a semi-analytical stationary model for calculating the midplane temperature of a gas and dust disk around a young star. The model takes into account gas and dust opacities, as well as the evaporation of dust at temperatures above 1000 K. Using this model, we calculate the midplane temperature distributions of the disk under various assumptions about the source of opacity and the presence of dust. We show that when all considered processes are taken into account, the heat balance equation in the region r<1 au has multiple temperature solutions. Thus, the conditions for thermal instability are met in this region. To illustrate the possible influence of instability on the accretion state in a protoplanetary disk, we consider a viscous disk model with alpha parameterization of turbulent viscosity. We show that in such a model the disk evolution is non-stationary, with alternating phases of accumulation of matter in the inner disk and its rapid accretion onto the star, leading to an episodic accretion pattern. These results indicate that this instability needs to be taken into account in evolutionary models of protoplanetary disks.Comment: Published in Astronomy Reports Vol. 67, No. 5, pp. 470-482 (2023

Surface Brightness Gradients Produced by the Ring Waves of Star Formation

We compute surface brightness profiles of galactic disks for outwardly propagating waves of star formation with a view to investigate the stellar populations in ring galaxies. 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. We show that the surface brightness profiles produced by both scenarios of ring formation are similar and are strongly sensitive to the velocity of the wave. The results of our computations are compared with the observational quantities sensitive to the young and old stellar populations in the ring galaxies A0035-335 (the Cartwheel galaxy) and VIIZw466. The best fit to the observed radial H_alpha surface brightness distribution in the Cartwheel galaxy is obtained for a wave velocity of about 90 km/s. The red continuum brightness of the ring can be fully explained by the evolving stars present in the trailing part of the wave. However the red continuum brightness in regions internal to the ring indicates that the wave of star formation propagates in a pre-existing stellar disk in the Cartwheel. The H_alpha and K-band surface brightness profiles in VIIZw466 match the values expected from stellar populations produced by a wave of star formation propagating in a purely gaseous disk very well. We conclude that VIIZw466 is probably experiencing the first event of star formation in the disk.Comment: Uses aas2pp4.sty and epsfig.sty, 15 pages To appear in Astrophysical Journal, March 10, 199

Синтаксономія угруповань дрібнолистяних лісів на заростаючих перелогах.

Досліджено спонтанні дрібнолистяні угруповання перелогів, які є першою стадією відновлення широколистяних лісів. В складі угруповань березових, осикових та вільхових молодняків на перелогах (Івано-Франківська та Житомирська обл.) виділено та описано відповідно три нові асоціації (Cirsio arvensi-Betuletum pendulae, Phalacrolomo annui-Populetum tremulae, Dauco carotae-Alnetum glutinosae). Дані синтаксони віднесено до нового класу Dactylo glomerati-Populetea tremulae Vorobyov et I. Solomakha cl. nova in press. Також узагальнено синтаксономію цього класу на території України

A Precision Measurement of Nuclear Muon Capture on 3He

The muon capture rate in the reaction mu- 3He -> nu + 3H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the mu-3He atom is (1496.0 +- 4.0) s^-1. This result confirms the PCAC prediction for the pseudoscalar form factors of the 3He-3H system and the nucleon.Comment: 13 pages, 6 PostScript figure

A high-pressure hydrogen time projection chamber for the MuCap experiment

The MuCap experiment at the Paul Scherrer Institute performed a high-precision measurement of the rate of the basic electroweak process of nuclear muon capture by the proton, $\mu^- + p \rightarrow n + \nu_\mu$. The experimental approach was based on the use of a time projection chamber (TPC) that operated in pure hydrogen gas at a pressure of 10 bar and functioned as an active muon stopping target. The TPC detected the tracks of individual muon arrivals in three dimensions, while the trajectories of outgoing decay (Michel) electrons were measured by two surrounding wire chambers and a plastic scintillation hodoscope. The muon and electron detectors together enabled a precise measurement of the $\mu p$ atom's lifetime, from which the nuclear muon capture rate was deduced. The TPC was also used to monitor the purity of the hydrogen gas by detecting the nuclear recoils that follow muon capture by elemental impurities. This paper describes the TPC design and performance in detail.Comment: 15 pages, 13 figures, to be submitted to Eur. Phys. J. A; clarified section 3.1.2 and made minor stylistic corrections for Eur. Phys. J. A requirement

Prescriptions for the scaling variable of the nucleon structure function in nuclei

We tested several choices of the in-medium value of the Bjorken scaling variable assuming the nucleon structure function in nucleus to be the same as that of free nucleon. The results unambiguously show that it is different.Comment: 11 pages, 3 figures, 1 tabl