An interactive procedure of a transverse beam matching and correction in INR Linac

An application package is developed to carry out an interactive procedure for a transverse beam matching and correction in INR Linac. The results of multiple beam profile measurements in several accelerator areas are used. The currents in steering coils are found to suppress the beam displacement. The gradients in quadrupole lenses are calculated to match the beam. This procedure is successfully used in accelerator tuning.Разработан пакет программ для проведения интерактивной процедуры поперечного согласования и коррекции пучка по результатам измерения профилей пучка на различных участках линейного ускорителя ИЯИ РАН. Определяются режимы включения корректирующих элементов для выведения пучка на ось ускорителя и градиенты полей квадрупольных линз для согласования пучка с фокусирующим каналом ускорителя. Разработанная процедура успешно используется при настройке режимов работы ускорителя.Розроблено пакет програм для проведення інтерактивної процедури поперечного узгодження і корекції пучка за результатами виміру профілів пучка на різних ділянках лінійного прискорювача ІЯД РАН. Визначаються режими включення коригувальних елементів для виведення пучка на вісь прискорювача і градієнти полів квадрупольних лінз для узгодження пучка з фокусуючим каналом прискорювача. Розроблена процедура успішно використається при настроюванні режимів роботи прискорювача

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

The On-orbit Calibrations for the Fermi Large Area Telescope

The Large Area Telescope (LAT) on--board the Fermi Gamma ray Space Telescope began its on--orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.Comment: 60 pages, 34 figures, submitted to Astroparticle Physic

Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

Gas motions in the plane of the spiral galaxy NGC 3631

Peer reviewe

Room-temperature photoluminescence of Ga0.96In0.04As0.11Sb0-89 lattice matched to InAs. .

Photoluminescence (PL) has been observed at room temperature from a Ga0.96In0.04As0.11Sb0.89 quaternary solid solution for the first time. High-quality epitaxial layers of n-type (Te-doped) Ga0.96In0.04As0.11Sb0.89 with low In content were grown by liquid phase epitaxy (LPE) lattice-matched to InAs(100) substrates from a Ga-rich melt. The PL properties of the material were investigated over a wide temperature range, and the principal radiative transitions were identified. In the temperature range <150 K, donor-acceptor recombination involving the first and second ionization state of native antisite defects was the dominant radiative-recombination process, whereas interband recombination was found to dominate at room temperature