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

Strangeness Production at COSY

The paper gives an overview of strangeness-production experiments at the Cooler Synchrotron COSY. Results on kaon-pair and phi meson production in pp, pd and dd collisions, hyperon-production experiments and Lambda p final-state interaction studies are presented.Comment: Proceedings of the 12th Int. Conf. on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2010) in Williamsburg (USA

Ion optics with electrostatic lenses

Ion optics with electrostatic lenses is presented using the standard matrix formalism of magnetic ion optics. We introduce the paraxial ray equation which is appropriate to systems with rotational symmetry. The rst-order solutions of the paraxial ray equation are derived. The resulting transport matrices can be used to study systems with acceleration tube lenses, aperture lenses, einzel lenses and dc accelerators. The analogy with geometrical optics is discussed. Beam transport and phase ellipses are described using the so-called matrices. The equations of the longitudinal transport matrix are derived. Besides rotational symmetric elements, electrostatic quadrupoles and electrostatic de- ectors are also presented. The effect of space charge forces is discussed

Electrostatic accelerators

The principle of electrostatic accelerators is presented. We consider Cockcroft Walton, Van de Graaff and Tandem Van de Graaff accelerators. We resume high voltage generators such as cascade generators, Van de Graaff band generators, Pelletron generators, Laddertron generators and Dynamitron generators. The speci c features of accelerating tubes, ion optics and methods of voltage stabilization are described. We discuss the characteristic beam properties and the variety of possible beams. We sketch possible applications and the progress in the development of electrostatic accelerators

Feminism and the Politics of Representation: Towards a Critical and Ethical Encounter with “Others”

This essay begins from the position that a speaking subject in feminism occupies a place of power and authority which requires a commitment to an ethical involvement in the representation of ‘others.’ Specifically, this essay will address feminist concerns of speaking for others and the concerns raised by the dangers of representing across differences of race, sexuality, gender and cultures. First, it will critique feminist claims to political effectivity as a solution to ethical representation. Second, it will look at how hierarchies of oppression and privileged ontological positions are inconsistently represented in feminist discussions. Lastly, it will briefly examine how differences between ‘others’ are increasingly being represented as cultural in potentially problematic ways. The essay will argue that feminist discussions of representation must be self-critical, but at the same time not abandon the task of working towards an ethical involvement with ‘others.

Wenn das Lesen noch immer stockt : Psychologen und Literaturdidaktiker entwickeln Methoden, um Lesetempo und -verständnis bei Hauptschülern zu fördern

Leseförderung ist seit den ernüchternden Ergebnissen der großen Vergleichsstudien wie PISA und DESI zu einem Dauerthema der deutschen Bildungspolitik und der pädagogischen Leseforschung geworden. Laut PISA-Studie 2000 bleiben rund 23 Prozent der 15-Jährigen beim Lesen unter dem als Mindeststandard definierten Leistungsniveau. Diese »Risikogruppe«, die zum Großteil aus Schülern und Schülerinnen der Hauptschulen besteht, kann altersangemessene Texte nicht adäquat lesen und verstehen. Die Folgen sind weitreichend und werden in der Öffentlichkeit mit Recht unter dem Schlagwort der »Bildungskatastrophe« diskutiert: Schwache Leser können dem textbasierten Unterricht in den verschiedenen Schulfächern meist nicht folgen und sich die Lerninhalte nicht aneignen, was schnell zu schlechten Leistungen in nahezu allen Fächern führt. Diese Jugendlichen erleben alltäglich schulische Misserfolge und können sich nicht angemessen für die stetig steigenden Anforderungen der beruflichen Praxis qualifizieren – in den meisten Fällen werden sie große Mühe haben, einen Ausbildungsplatz zu finden. Die »poor readers« im Bildungskeller der deutschen Schullandschaft sind die wahren Verlierer der sich gegenwärtig etablierenden Informations- und Wissensgesellschaft: Sie steuern bereits im Jugendalter auf Arbeitslosigkeit und gesellschaftliche Desintegration zu. ..

Arbeit, Wirtschaft, Umwelt: Einige Indikatoren sozialer, wirtschaftlicher und ökologischer Entwicklung im Zeitablauf

--

An Artificial Neural Network Based Robot Controller that Uses Rat’s Brain Signals

Brain machine interface (BMI) has been proposed as a novel technique to control prosthetic devices aimed at restoring motor functions in paralyzed patients. In this paper, we propose a neural network based controller that maps rat’s brain signals and transforms them into robot movement. First, the rat is trained to move the robot by pressing the right and left lever in order to get food. Next, we collect brain signals with four implanted electrodes, two in the motor cortex and two in the somatosensory cortex area. The collected data are used to train and evaluate different artificial neural controllers. Trained neural controllers are employed online to map brain signals and transform them into robot motion. Offline and online classification results of rat’s brain signals show that the Radial Basis Function Neural Networks (RBFNN) outperforms other neural networks. In addition, online robot control results show that even with a limited number of electrodes, the robot motion generated by RBFNN matched the motion generated by the left and right lever position

Study of the Λp\Lambda p Interaction Close to the Σ+n\Sigma^+n and Σ0p\Sigma^0p Thresholds

The $\Lambda p$ interaction close to the $\Sigma N$ threshold is considered. Specifically, the pronounced structure seen in production reactions like $K^-d \to \pi^- \Lambda p$ and $pp\to K^+ \Lambda p$ around the $\Sigma N$ threshold is analyzed. Modern interaction models of the coupled $\Lambda N - \Sigma N$ systems generate such a structure either due to the presence of a (deuteron-like) unstable bound state or of an inelastic virtual state. % A determination of the position of the prominent peak as observed in various experiments for the two aforementioned reactions leads to values that agree quite well with each other. Furthermore, the deduced mean value of $2128.7\pm 0.3$ MeV for the peak position coincides practically with the threshold energy of the $\Sigma^+ n$ channel. This supports the interpretation of the structure as a genuine cusp, signaling an inelastic virtual state in the $^3S_1-^3D_1$ partial wave of the $\Sigma N$ isospin 1/2 channel. % There is also evidence for a second peak (or shoulder) in the data sets considered which appears at roughly 10-15 MeV above the $\Sigma N$ threshold. However, its concrete position varies significantly from data set to data set and, thus, a theoretical interpretation is difficult.Comment: accepted for publication Nucl. Phys.