Development of a Momentum Determined Electron Beam in the 1 -45 GeV Range

A beam line for electrons with energies in the range of 1 to 45 GeV, low contamination of hadrons and muons and high intensity up to 10^6 per accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A beam tagging system based on drift chambers with 160 micron resolution was able to measure relative electron beam momentum precisely. The resolution sigma_p p was 0.13% at 45 GeV where multiple scattering is negligible. This test beam setup provided the possibility to study properties of lead tungstate crystals (PbWO_4) for the BTeV experiment at Fermilab.Comment: 12 pages, 8 figures; work done by the BTeV Electromagnetic Calorimeter grou

Hyperfine structure of the ground state muonic He-3 atom

On the basis of the perturbation theory in the fine structure constant $\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\mu\ e \ ^3_2He)$. We obtain total result for the ground state hyperfine splitting $\Delta \nu^{hfs}=4166.471$ MHz which improves the previous calculation of Lakdawala and Mohr due to the account of new corrections of orders $\alpha^5$ and $\alpha^6$. The remaining difference between our theoretical result and experimental value of the hyperfine splitting lies in the range of theoretical and experimental errors and requires the subsequent investigation of higher order corrections.Comment: Talk on poster section of XXIV spectroscopy congress, 28 February-5 March 2010, Moscow-Troitsk, Russia, 21 pages, LaTeX, 8 figure

H⁻ injector for Moscow meson factory linac

Status report is presented for an H⁻ injector being now under construction. The injector parameters are as follows: energy − 400 keV; average beam current − 400 µA; beam pulse duration − up to 200 µs; pulse repetition rate − 50 Hz. A pulsed high-voltage generator and a surface-plasma ion source power supply have been developed and manufactured.Представлено состоянии работ по созданию инжектора отрицательных ионов водорода с энергией 400 кВ, который должен обеспечить средний ток пучка ионов до 400 мкА при длительности импульса тока до 200 мкс и частоте повторения импульсов 50 Гц. Разработаны, изготовлены и смонтированы генератор ускоряющего импульсного напряжения и система питания поверхностно-плазменного ионного источника.Представлено звіт про стан робіт зі створення інжектора негативних іонів водню з енергією 400 кВ, що повинен забезпечити середній струм пучка іонів до 400 мкА при тривалості імпульсу струму пучка до 200 мкс і частоті повторення імпульсів 50 Гц. Розроблено, виготовлені і змонтовані генератор прискорювальної імпульсної напруги і система живлення поверхнево-плазмового іонного джерел

Study of Radiation Damage in Lead Tungstate Crystals Using Intense High Energy Beams

We report on the effects of radiation on the light output of lead tungstate crystals. The crystals were irradiated by pure, intense high energy electron and hadron beams as well as by a mixture of hadrons, neutrons and gammas. The crystals were manufactured in Bogoroditsk, Apatity (both Russia), and Shanghai (China). These studies were carried out at the 70-GeV proton accelerator in Protvino

Large-Scale Disturbances Features Induced in the Ionosphere by Powerful Decameter Radiation during Moderate Magnetic Storms

Abstract—: The paper presents the results of experimental studies of aperiodic and quasi-periodic disturbances in the ionosphere that were observed under the influence of powerful radiation from the SURA facility on the ionospheric plasma in quiet and magnetically disturbed conditions. A vertical Doppler sounding radar located at a distance of ~960 km from the heating facility was used for diagnostics. The recorded aperiodic disturbances with a delay of ~25 min are most likely associated with the generation of a shock-wave disturbance related to atmospheric gravity waves. Quasiperiodic disturbances of 12–15 min had a period equal to the period of the heating cycle. In other cases, the period of disturbances was equal to the period of natural oscillations of the air in the atmosphere. The speed of quasi-periodic disturbances was 300–400 m/s. The effects of the artificial generation of plasma turbulence, the joint action of solar terminator and powerful radiation, and the resonance effects associated with the impact of radio waves with a frequency equal to the fourth harmonic of the electron gyrofrequency on the ionosphere are found. The role of magnetic activity in the Earth–atmosphere–ionosphere–magnetosphere system, which determined the nature of disturbances in the ionosphere, is noted

Relationship between the Potential of an Artificial Earth Satellite and the Temperature of Electrons in the Upper Ionosphere Perturbed by High-Power Short-Wave Radiation of the “Sura” Ground-Based Facility

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. We discuss the relationship between the electron temperature and the potential of the body of an artificial Earth satellite in the upper ionosphere. The formula for the spacecraft potential is analyzed, and the limitations of the theoretical representation are shown. The experimental results obtained within the framework of the Sura—DEMETER and Sura—SWARM programs are considered and serve as the basis for analysis of three cases: (i) when artificial ionospheric inhomogeneities are excited in the upper ionosphere stimulated by high-power short radio waves, (ii) when no inhomogeneities are excited in the process of stimulation of the upper ionosphere, and (iii) when measurements were performed in the natural ionosphere. It was found that the greatest value of the coefficient of correlation between the variations in the electron temperature and the spacecraft potential is observed in the presence of the ionospheric inhomogeneities. The applied relevance of the obtained results is discussed

Degree Spectra of Structures

In this survey, we discuss computability spectra of countable structures that provide a natural measure of non-computability of a structure. This notion is a main tool for investigating algorithmic properties of countable structures. Along with a review of known results in this field, we present proofs of some new results to illustrate the method of interpretation, which is a basic method of the field. We also discuss some open questions