Issue 6, 2025

Exclusive neutral pion electroproduction off protons from CLAS12 data at beam energy 6.535 GeV

V. B. Ryzhkov$^1$, A. N. Pavlova$^1$, A. A. Rusova$^{1,2}$, E. L. Isupov$^2$

The first results on the selection of $ep\to e'p'\pi^0$ events from the CLAS12 detector experimental data in the resonance area for the electron beam energy $E_e = 6.535$ GeV are presented in this report. The topology with two detected photons in the final state is analyzed; selections are introduced to isolate events of the single neutral pion electroproduction reaction; the invariant mass of photon pair distributions in various kinematic bins are obtained for the total energy of final hadrons in the $\gamma_v p$ center of mass system $W$ and the photon virtuality $Q^2$. The reaction yields are calculated. The topology with one detected photon is also considered; additional kinematic selections are introduced for this topology.

$B^- \rightarrow \mu^+ \mu^- e^- \bar{\nu}_e$ decay in orthogonal amplitudes method

D. S. Ostapovich

In the present paper partial widths and differential ditributions of $B^- \rightarrow \mu^+ \mu^- e^- \bar{\nu}_{e}$ and $B^- \rightarrow e^+ e^- \mu^- \bar{\nu}_{\mu}$ decays were calculated, utilizing the orthogonal amlitudes method. Virtual photon emission by the light quark (VMD model), virtual photon emission by the heavy quark and bremsstrahlung were accounted for in calculations. The results obtained are in a satisfactory agreement with experimental constraints.

Определение характеристик пластиковых сцинтилляционных детекторов

P. G. Filonchik$^{1,2}$, D. N. Grozdanov$^{2,3}$, Yu. N. Kopach$^2$, P. S. Prusachenko$^2$, N. A. Fedorov$^2$, I. N. Ruskov

В Объединённом институте ядерных исследований (ОИЯИ) в Лаборатории нейтронной физики им. Франка (ЛНФ) в группе TANGRA проводится эксперимент по исследованию угловых корреляций в реакции неупругого рассеяния нейтронов с энергией 14,1 МэВ на ядрах углерода. Для регистрации нейтронов использовались 10 длинных (1 метр) пластиковых сцинтилляционных детекторов производства компании EPIC CRYSTAL. Их особенностью является наличие двух фотоэлектронных умножителей (ФЭУ), благодаря чему они обладают позиционной чувствительностью. В настоящей работе были выполнены измерения характеристик этих детекторов: пространственное разрешение и коэффициент затухания.

The effect of the addition of neptunium on the duration of the fuel campaign in the BN reactor

V. A. Pavlovich, M. A. Kharkov, V. O. Skulkin

The aim of the work is to evaluate the possibility of using neptunium as fuel for the BN-600 reactor and its subsequent effect on the length of the fuel campaign. To carry out the calculations, neutron physics and thermophysical models of fuel assemblies of reactors were created. Neptunium was added to the main fuel homogeneously in various proportions ranging from 1 to 20% in the form of NpO2 oxide. The characteristics under consideration are the neutron multiplication coefficient in an infinite medium, and the spatial temperature distribution in the fuel element. The homogeneous addition of neptunium to the fuel has a negative effect on Keff. Adding a fraction of neptunium oxide of more than 5% is impractical. The addition of neptunium also had a negative effect on the energy release values, but to a lesser extent. When neptunium is added, the temperature of the BN-600 fuel rods changes by 2-3% at the fuel assembly inlet and outlet.

Space-like pion off-shell form factors in the Bethe-Salpeter approach

S. G. Bondarenko$^{1,2}$, M. K. Slautin$^{1,2}$

In the paper, the off-shell electromagnetic pion form factors in the Bethe-Salpeter formalism are considered. The separable kernel of the first rank quark-antiquark interaction is used to solve the equation analytically.The semi-off-shell pion form factors 𝐹1 and 𝐹2, which are related to each other by the Ward-Takahashi identity, are calculated. The obtained off-shell form factors as well as static properties of the pion are compared with the results of other authors

A new technique for controlling scale discreteness in a differential mobile refractometer

A. D. Belyaev, V. V. Davydov

The necessity of developing a small-sized mobile refractometer for express control of the state of hydrocarbon media and a new method for determining their composition and concentration of components in case the medium is a mixture of two hydrocarbon media is substantiated. This method will allow for comprehensive control of hydrocarbon media at the sampling site and making an informed decision on their intended use without additional studies in a stationary laboratory. This will save time and resources when solving many problems related to the use of fuel (for example, for mobile objects, etc.). The new method is characterized by the speed of measurements and does not require special sample preparation. The error in measuring the refractive index is ± 0.0002, which is sufficient for reliable express control. The studies of hydrocarbon media and their mixtures confirmed the adequacy of the development and the reliability of determining the composition of the hydrocarbon mixture and the concentration of components.

Analysis of changes in the orientation of the S-net network bottom seismometers for the period 2018-2024.

O. V. Ponomarev$^1$, S. V. Kolesov$^{1,2}$

The spatial orientation stability of seismometers deployed at four S-net seafloor observatories was investigated using cross-spectral analysis of seismic records from strong earthquakes. Data from three events (Gulf of Alaska, 23 Jan 2018; Chignik, 29 Jul 2021; Noto Peninsula, 01 Jan 2024; all Mw > 7.5), evenly spaced throughout the 2018–2024 observation window, demonstrate that the instrument orientations remained invariant to within an estimated error of 1 degree over the six-year period.

S. A. Kotov, Z. V. Naumova, T. S. Kudryavtseva, V. V. Davydov, O. I. Suchkova

One of the tasks of applied physics is to develop new methods for the use of condensed media, which are waste from various industries. In this case, several problems are solved, both related to ecology in its various applications, and to the production of various elements using physico-chemical processes. The paper considers rolling scale, which is formed in large quantities during the operation of metallurgical enterprises. One of the possible options for recycling rolled scale (recycling) is related to the possibility of its use as a sorbent in liquid purification and filtration systems. Morphological, chemical, and phase features of rolled scale are considered to determine its potential for sorption activity. Using spectral studies, a comparative analysis of magnetic and non-magnetic fractions was carried out, and differences in the content of iron-containing phases and impurity elements were revealed. It is established that the microstructure and composition of the material are determined by the conditions of its formation and directly affect the adsorption characteristics. The presence of magnetite and a porous structure contributes to the formation of an active surface for the deposition of chemically active elements on it, such as phosphorus, zinc and other dangerous elements that are not removed by mechanical filtration.