The multibeam linear ion accelerator: calculation and experiment

The accelerating structure consisting of cylindrical screen with electrodes of coil types radialy disposed, which the current-conductive annuluses with tubes of driftage disposed azimuth of annulus are attached has been suggested. By way computer simulation were received the base-frequency of structure, shunt-impedance, distribution of field in the accelerating gaps. The experimental researched of frequencies generation coil in screen and field distribution functions were made.Пропонується прискорююча структура, що складається з циліндричного екрану з радіально розташованими електродами спірального типу, до яких кріпляться струмопровідні кільця з трубками дрейфу, розташованими по азимуту кільця. Шляхом чисельного моделювання були отримані робоча частота, шунтовий імпеданс, розподіл полів в прискорюючих зазорах. Проведено експериментальні дослідження частот збудження спіралі в екрані і розподілу полів.Предлагается ускоряющая структура, состоящая из цилиндрического экрана с радиально расположенными электродами спирального типа, к которым крепятся токопроводящие кольца с трубками дрейфа, расположенными по азимуту кольца. Путем численного моделирования были получены рабочая частота, шунтовой импеданс, распределение поля в ускоряющих зазорах. Проведены экспериментальныеисследования частот возбуждения спирали в экране и распределения поля

Numerical modelling of multibeam accelerating structures

The three-dimensional multibeam numerical simulation has been carried out on the basis of integral equations. Dispersion equations and expressions for shunt impedance and Q-factor have been obtained for E and H oscillations in cylindrical cavities. The tensor Green function and filament-like representation of the beam were used.На основі методу інтегральних рівнянь проведене тривимірне чисельне моделювання багатопроменевих прискорюючи структур. Для Е- и Н- резонаторів при використанні нитковидного зображення струму джерела і тензорної форми функції Гріна для циліндричного резонатора отримані дисперсійні рівняння, вирази для шунтового імпедансу і добротності.На основе метода интегральных уравнений проведено трехмерное численное моделирование многолучевых ускоряющих структур. Для Е- и Н- резонаторов при использовании нитевидного представления тока источника и тензорной формы функции Грина для цилиндрического резонатора получены дисперсионные уравнения, выражения для шунтового импеданса и добротности

Observation of a multichannel interdigital H-structure

The paper presents the experimental results together with their comparison with calculations. The relation between a bunch charge in accelerating channel and a variation of resonant wave-length at asymptotic alternatingphase focusing is derived. Suggested is also a new way for computation of high-frequency characteristics of the accelerating structure taking into account the variation of resonant frequency with constant transversal dimensions of the structure.Приведены результаты эксперимента, сравнение полученных данных с расчетными величинами. Получено выражение зависимости заряда сгустка в ускоряющем зазоре от изменения резонансной длины волны для ассиметричной фазопеременной фокусировки. Приведены результаты нового способа расчета ВЧ-параметров предложенной структуры с учетом фактора изменения длины волны при постоянстве поперечных размеров ускоряющей структуры.Наведені результати експерименту, порівняння отриманих даних з розрахунковими величинами. Отримано вираження залежності заряду згустку в прискорювальному зазорі від зміни резонансної довжини хвилі для асиметричного фазозмінного фокусування. Наведено результати нового способу розрахунку ВЧ- параметрів запропонованої структури з урахуванням фактора зміни довжини хвилі при сталості поперечних розмірів прискорювальної структури

Multi-beam accelerating module calculation

As has been pointed in [1], a multi-beam accelerating cavity with drift tubes is suggested to be used in a linac for the purpose of overcoming limitations on the mean current. In this paper the dispersion equation for such a construction was deduced and analyzed

Computational chemistry applied to problems in electrochemistry - selected exsamples and perspectives

Computational approach in electrochemistry, being complementary to the experimental one, provides important information regarding the electrode processes on atomic level. In this contribution, applicability of computational approach to the problems related to electrocatalysis at different levels of complexity is demonstrated Starting with simple problem of modification of Pd(111) surface with other metal atoms, the data regarding electronic structure and periodic trends upon surface functionalization with p-elements have been offered. Next, Cl adsorption on Pd3M alloys (M = Fe, Co, Ni, Pd, Rh) and Pd monolayers over (111) surfaces of coinage metals has been analyzed. Besides strong correlation of adsorptive properties and electronic structure, structural changes invoked by Cl adsorption are predicted. Brief overview of mechanistic analysis of ORR on Pt(hkl) surfaces is provided, allowing identification of rate determining steps on different surfaces and reaction paths, finally resulting in simulation of stationary ORR currents. Possibilities and strategies of computational approach in rational design of new electrocatalytic materials are discussed.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

High-current ion linac calculation

The research on multibeam ion accelerators has been carried. Full analysis of the oscillating system on example of a HCIL cell containing a pair of conducting rings (CR) with drift tubes (DT) and a central drift channel was carried out. High-current electronic beam is used as an electromagnetic power supply, which not exclude an external power source. Interaction factor of an electronic beam with a field of about 100%, kiloampere currents and megawatt power levels allows to produce a compact electron-beam pumping system with drift tubes shorter then wavelength

Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits

The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using Kinematic Characteristics of Lepton + Jets Events

We present a measurement of the top quark pair ttbar production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1} of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the ttbar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1} (syst) +/-0.4 (lumi) pb, in good agreement with the standard model prediction.Comment: submitted to Phys.Rev.Let

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Lepton + Jets Events with Lifetime b-tagging

We present a measurement of the top quark pair ($t\bar{t}$) production cross section ($\sigma_{t\bar{t}}$) in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using 230 pb$^{-1}$ of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the $t\bar{t}$ purity of the selected sample. For a top quark mass of 175 GeV, we measure $\sigma_{t\bar{t}}=8.6^{+1.6}_{-1.5}(stat.+syst.)\pm 0.6(lumi.)$ pb, in agreement with the standard model expectation.Comment: 7 pages, 2 figures, 3 tables Submitted to Phys.Rev.Let