Vol 3, No 3 (2019)


197-203 413

To synthesis of superheavy elements, the shell structure is very important not only in the stability of nuclei, but also the fusion process, especially the cold fusion reaction. We employ the Langevin equation with the microscopic transport coefficients and calculate the fusion cross section for the reaction70Zn+208Pb→278Cn. In the dynamical process, the effect of nuclear structure is discussed.

204-218 449

Recently in the WWR-K water-water research reactor the former HEU fuel, enriched to 36% in Uranium- 235, was changed to LEU one, enriched to 19.7%, with substantial change of the core configuration. In view of reactor conversion, a new Safety Analysis Report (SAR) was developed for the WWR-K reactor. Substantiation of reactor safe operation under both normal operation and emergency conditions was done under thermal-hydraulic approach. In the analysis developed prior to physical start up it was assumed that a main circulation pump (MCP) provides the coolant flow rate in the core equal to 350 m 3 /h (a certified value for the pump CB-321). However, in course of the reactor physical start up it was found that it is only 250 m 3 /h. The reason was a decision of the reactor staff to reduce the primary pump power consumption, prolonging its life time.Therefor the thermal hydraulic analysis was revised, and the SAR was renewed. Safety analysis implies also consideration of some potential initiating events capable to develop into an accident. So, several typical initiating events are subject to thermal-hydraulic analysis to substantiate observance of nuclear and radiation safety in emergency situations. It is shown that, owing to proper operation of safety systems, the initiating events under consideration don’t result into accidents, if two primary pumps provide not more than 585 m 3 /h.

219-225 434

The paper is devoted to the neutron-physical parameters obtained via combined calculations and experimental measurements for the exit of the WWR-K reactor beam tube. The experimentally measured values of the thermal and fast neutron flux densities at the exit comprise 9.6 × 108 and 8.4 × 107 cm-2 s-1 , respectively. The dose rate of gamma-emission is 30 Sv/h. The obtained parameters will be used in designing of the collimation and screening systems of the installation for radiography and tomography to be created at the beam tube #1.

226-232 412

At the High mountain station of cosmic rays at an altitude of 3340 meters above sea level in 2018, work on modernization of registration of radio emission from extensive air showers was carried out. To date, 4 radio antennas have been installed in the direction of north, south, west, east at a distance of 30 meters from the registration center. Registration is carried out in the frequency range 30 - 80 MHz. As a result of the preliminary experiment, some event candidates were selected that demonstrate the presence of a noticeable radio signal pulse in the vicinity of the nearest EAS arrival time 1 - 3 µs. The features of the particle density distribution in these events suggest that most of them have a fairly high primary energy E0 > (2 - 5) 1016 eV and the shower center is close to the radio antenna, therefore the coincidence time of the observed radio pulse with the arrival time of the shower front in these events can not be completely random. Consequently, the radio antenna system installed on the Tien Shan, together with the developed software for recording the signal, really provides an effective choice of radio emission from EAS particles, and further work in this direction should be seriously considered.

233-241 425

The complex EAS installation of the Tien Shan mountain cosmic ray station which is situated at a height of 3340 m above sea level includes the scintillation and Cherenkov detectors of charged shower particles, an ionization calorimeter and a set of neutron detectors for registering the hadronic component of the shower, and a number of underground detectors of the penetrative EAS component. Now it is intended to expand this installation with a promising method for detecting the radio-emission generated by the particles of the developing shower. The facility for radio-emission detection consists of a three crossed dipole antennae, one being set vertically, and another two - mutually perpendicularly in a horizontal plane, all of them being connected to a three-channel radio-frequency amplifier of German production. By the passage of an extensive air shower, which is defined by a scintillation shower detector system, the output signal of antenna amplifier is digitized by a fast multichannel DT5720 ADC of Italian production, and kept within computer memory. The further analysis of the detected signal anticipates its operation according to a special algorithm and a search for the pulse of radio-emission from the shower. A functional test of the radio-installation is made with artificial signals which imitate those of the shower, and with the use of a N1996A type wave analyzer of Agilent Technologies production. We present preliminary results on the registration of extensive air shower emission at the Tien Shan installation which were collected during test measurements.

242-253 489

The neutrons scattering and capture cross-section processes has been calculated for natural28Si ,29Si ,30Si isotopes which are main part of nanosilicon samples when irradiated for 20 hours by epithermal neutron flux. The values of energies has been determined which given to nanosilicon nuclei as a result of scattering processes in the energy intervals of investigated neutrons. The cross-sections of radiation capture process and the amount of31Si radioactive isotope which can be formed by by30Si isotope in the energy interval of epithermal neutrons, the parameters of energy supply and ionization processes has been determined by interaction between energy carried of β - particles which disseminated in evironment and silicon atoms as a result of their β - decay. The formed defects has been determined in electron structure of nanosilicon under the influence of primary and secondary electron beams. Characterized interaction processes between nanosilicon and gamma rays irradiated from radioactive isotopes in impurities up to 1% in nanosilicon which formed under the influence of neutron flux. As a result of SEM investigation, interaction between surface defects inherent to nanoscale systems and O2 , H2O active components that arranged environment and increasing number of surface oxidation atoms determined under the influence of radiation from radioactive isotopes which are product of radiation capture processes when impact by neutron flux. The progression of agglomeration processes of nanosilicon particles under the influence of secondary radiation processes that caused by neutron flux has also been proved experimentally by SEM investigations. The characteristic of identification and generation processes of paramagnetic defects, that formed as a result of secondary radiation processes investigated by electron paramagnetic resonance spectroscopy method.

254-259 409

The change in the electrical properties of the Si(111) and Si(100) surfaces during ion implantation and subsequent annealing was studied. The possibilities of controlling of the electrophysical properties of the Si(111) and Si(100) surface layers by the implantation of ions of alkaline and alkaline-earth elements are analyzed. Some electrophysical properties of semiconductors containing p- and n-structures and the possibilities of their application in electronics are discussed.

260-268 408

This paper presents the results of a study of the structural characteristics of perovskite systems based on YTiOx. These samples were subjected to heat treatment in the process of solid-phase synthesis. The change in physicochemical properties was investigated by scanning electron microscopy, X-ray structural and energy dispersive analysis. In the course of the work, it was found that the synthesized samples are a mixture of three phases characteristic of yttrium compounds with titanium. A quantitative change in the phases during the heat treatment indicates phase transformations and a change in the basic crystallographic characteristics. The results of these studies indicate that during thermal annealing, the density of perovskites changes, indicating phase transformations due to the mobility of impurity defects and distortion of the crystal lattice.

269-278 429

In the present paper, the magnetic susceptibility have been studied under the effect of pressure at constant temperature in samarium chalcogenides (SmX, X=S, Se and Te). The samarium chalcogenides have predicted the pressure induced structural and electronic transition from NaCl structure (FCC lattice) to CsCl structure (BCC lattice). The f energy level of electrons in the compounds (SmX, X=S, Se and Te) have been shifted towards 5d conduction band due to the influence of pressure at constant temperature. The variation of the magnetic susceptibility under the effect of pressure at constant temperature have been calculated. The calculated values and parameters are in close agreement with the experimental results.

ISSN 2522-9869 (Print)
ISSN 2616-8537 (Online)