Induced current in the presence of magnetic flux tube of small radius

The induced current density, corresponding to the massless Dirac equation in (2+1) dimensions in a magnetic flux tube of small radius is considered. This problem is important for graphene. In the case, when an electron can not penetrate the region of nonzero magnetic field, this current is the odd periodical function of the magnetic flux. If the region inside the magnetic tube is not forbidden for penetration of electron, the induced current is not a periodical function of the magnetic flux. However in the limit $R\to 0$, where $R$ is the radius of magnetic flux tube, this function has the universal form which is independent of the magnetic field distribution inside the magnetic tube at fixed value of the magnetic flux.Comment: 5 pages, 1 figur

Ultrasensitive 3He magnetometer for measurements of high magnetic fields

We describe a 3He magnetometer capable to measure high magnetic fields (B > 0.1 Tesla) with a relative accuracy of better than 10^-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2* being of order minutes which is achieved for spherical sample cells in the regime of motional narrowing where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in-situ using a new, non-standard variant of the metastability exchange optical pumping. We show that miniaturization helps to increase T2* further and that the measurement sensitivity is not significantly affected by temporal field fluctuations of order 10^-4.Comment: 27 pages, 7 figure

Forecasting investments in fixed assets

The article details the issues of forecasting investments in fixed assets. The theoretical aspects (foreign experience) of using various forms of predictive models based on the analysis of foreign scientific literature are considered. Two different forecasting methods have been practically implemented using the example of building multiplicative and ARIMA models. Quarterly forecasts of the cost of investments in fixed assets for 2022–2023 in the Russian Federation are formulated. A comparison of the simulation results showed that the calculated values for both models describe the dynamics of the indicator well, the forecast values differ, and therefore an average (combined) forecast is built based on the prediction results for both implemented methods. The results of the study can be used in the practical activities of state and municipal bodies, enterprise management for quarterly forecasting of investments in fixed assets

Statistical analysis of divorce status and causes in the Russian Federation

The article presents the results of a statistical analysis of the breeding rate in Russia. The annual data characterizing the number of divorces in 2000−2021 are considered, unstable dynamics is noted, which is generally characterized by a tendency of their decline. The dynamics of the indicator according to short-term data has showed the presence of seasonal fluctuations, seasonality indices have been calculated, a seasonal wave graph has been constructed. Based on the analysis of sociological research data, the reasons for divorces have been identified. On the basis of statistical data, the indicators that have statistical links with the general coefficient of divorce are identified and have an impact on it. These variables have been grouped by individual characteristics, the following groups of factors are formed: demographic factors; income and employment; housing conditions; public health; digital environment. With the help of correlation and regression analysis, linear models have been built for individual groups of factors, and a generalised model. By comprehensively influencing the indicators included in the model, it is possible to adjust the values of the total dilution coefficient for the future. Based on cluster analysis, regions with high, medium and low breeding rates have been identified. The results of the study can be useful to state bodies in the framework of their practical activities

Bremsstrahlung in alpha-Decay Reexamined

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of 210Po has been performed, which allows to follow the photon spectra up to energies of ~ 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasi classical approximation as well as with the exact quantum mechanical calculation. It is shown that due to the small effective electric dipole charge of the radiating system a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.Comment: 10 pages, 5 figures, v2: fix of small typo

Virtual light-by-light scattering and the g factor of a bound electron

The contribution of the light-by-light diagram to the g factor of electron and muon bound in Coulomb field is obtained. For electron in a ground state, our results are in good agreement with the results of other authors obtained numerically for large Z. For relatively small Z our results have essentially higher accuracy as compared to the previous ones. For muonic atoms, the contribution is obtained for the first time with the high accuracy in whole region of Z.Comment: 10 pages, 3 figures, RevTe

Crystal experiments on efficient beam extraction

Silicon crystal was channeling and extracting 70-GeV protons from the U-70 accelerator with efficiency of 85.3+-2.8% as measured for a beam of 10^12 protons directed towards crystals of 2 mm length in spills of 1-2 s duration. The experimental data follow very well the prediction of Monte Carlo simulations. This success is important to devise a more efficient use of the U-70 accelerator in Protvino and provides a crucial support for implementation of crystal-assisted collimation of gold ion beam in RHIC and slow extraction from AGS onto E952, now in preparation at Brookhaven Nat'l Lab. Future applications, spanning in the energy from sub-GeV (medical) to order of 1 GeV (scraping in the SNS, extraction from COSY) to order of 1 TeV and beyond (scraping in the Tevatron, LHC, VLHC), can benefit from these studies.Comment: 12pp. Presented at 19-th Intern. Conference on Atomic Collisions in Solids (ICACS-19: Paris, July 29 - August 3, 2001