Beam Performance and Luminosity Limitations in the High-Energy Storage Ring (HESR)

The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton synchrotron and storage ring in the momentum range from 1.5 to 15 GeV/c. An important feature of this new facility is the combination of phase space cooled beams with dense internal targets (e.g. pellet targets), resulting in demanding beam parameter of two operation modes: high luminosity mode with peak luminosities up to 2*10^32 cm-2 s-1, and high resolution mode with a momentum spread down to 10^-5, respectively. To reach these beam parameters very powerful phase space cooling is needed, utilizing high-energy electron cooling and high-bandwidth stochastic cooling. The effect of beam-target scattering and intra-beam interaction is investigated in order to study beam equilibria and beam losses for the two different operation modes.Comment: 8 pages, based on a talk presented at COULOMB'05, Accepted for publication by Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipmen

Ambient betatron motion and its excitation by ghost lines in Tevatron

Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time varying ghost lines in the betatron spectra are reported.Comment: 9 p

Use of high throughput sequencing to observe genome dynamics at a single cell level

With the development of high throughput sequencing technology, it becomes possible to directly analyze mutation distribution in a genome-wide fashion, dissociating mutation rate measurements from the traditional underlying assumptions. Here, we sequenced several genomes of Escherichia coli from colonies obtained after chemical mutagenesis and observed a strikingly nonrandom distribution of the induced mutations. These include long stretches of exclusively G to A or C to T transitions along the genome and orders of magnitude intra- and inter-genomic differences in mutation density. Whereas most of these observations can be explained by the known features of enzymatic processes, the others could reflect stochasticity in the molecular processes at the single-cell level. Our results demonstrate how analysis of the molecular records left in the genomes of the descendants of an individual mutagenized cell allows for genome-scale observations of fixation and segregation of mutations, as well as recombination events, in the single genome of their progenitor.Comment: 22 pages, 9 figures (including 5 supplementary), one tabl

Аналитическое решение некоректних задач динамическими методами

Апроксимація неперервних диференційних та інтегральних рівнянь скінченними дискретними алгебраїчними системами, локальна лінеаризація систем нелінійних рівнянь за заданою інформацією у разі вирішення обернених задач зводиться до задач розв’язку систем лінійних алгебраїчних рівнянь. Матриці таких систем зазвичай є погано обумовленими, тому задачі розв’язання таких систем є некоректними, оскільки порушується третя умова коректності за Адамаром. Для розв’язання некоректних задач запропоновано динамічний метод регуляризації [1]. З метою зменшення часу роботи алгоритму, що пропонується динамічним методом запропоновано модифікований метод - динамічний метод другого порядку. Розроблено математичний апарат та на його основі запропоновано алгоритм для модифікованого методу, а також показано його ефективність на практичному прикладі.The inverse problems of continuous differential and integral equations approximation with finite discrete algebraic systems and the problems of local linearization of nonlinear equations by the provided information are reduced to solving the linear algebraic systems. Matrices of such systems are usually ill-conditioned due to ill-posed problems according to Hadamard correctness. As a solution to these problems a dynamical method for regularization was proposed [1]. In order to reduce the computation time of the algorithm, a second order modification of the dynamical method is proposed. This paper provides mathematical tools based on this method. A practical example shows its effectiveness.Апроксимация непрерывних дифференциальных и интегральных уравнений конечными дискретними алгебраическими системами, локальная линеаризация нелинейных уравнений по заданой информации при решении обратных задач сводятся к задачам решения систем линейных алгебраических уравнений. Матрицы таких систем обычно плохо обусловлены, поэтому задачи их решения некоректны, поскольку нарушается третье условие коректности по Адамару. Для решений некоретных систем предложен динамический метод регуляризации некоректных задач [1]. С целью уменьшения времени работы алгоритма, который предлагается динамическим методом, предложен модифицированный метод – динамический метод второго порядка. Разработан математический аппарат и на его основании предложен алгоритм для модифицированного метода, а также показана его эффективность на практическом примере

Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses

Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with electron lenses, novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with electron lenses, novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position/ we explore the effects of electron-beam imperfections and noises/ and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses