Design and optimization of the lattice of the superconducting synchrotron SIS300 for slow extraction
Ángela Saá Hernández
- The superconducting synchrotron SIS300 is planned to be built at the new Facility for Antiproton and Ion Research (FAIR), at GSI-Darmstadt . SIS300 will be a versatile machine, which by means of a low-energy stretcher-mode or a high-energy ramped-mode will provide slowly extracted heavy ion beams towards the experimental areas. To reach the required maximum field of 4.5 T, cos(θ) magnets are necessary. Thus, SIS300 will become the first superconducting synchrotron worldwide with cos(θ) magnets providing resonant slow extraction.
Since SIS300 will be installed in the same tunnel as the SIS100 synchrotron, the dipole layout of SIS300 cannot be freely chosen. Thus, a standard lattice cannot be applied. A redesign of the SIS300 lattice accepting compromises concerning the positions and phase advances between the optical elements has been proposed. Using the analytical model of the slow extraction, firstly proposed by Kobayashi, and the analytical description of the resonance driving modes, a multiobjective optimization algorithm has been developed for the optimization of the lattice under the given boundary conditions. The final goal of the lattice optimization is a higher efficiency of the slow extraction. The results are evaluated by means of tracking simulations performed with the code Elegant.
The field quality in superconducting cos(θ) magnets is determined by the positions of the superconducting cable and the static and time-dependent effects of the current in the cable. Furthermore, the fast ramp rates of 1 T/s in the dipoles, which are fifty times faster than in any other superconducting cos(θ) magnet, together with the fact that the aperture is smaller than in conventional accelerator magnets, makes it extremely difficult to obtain a high-quality magnetic field. The unavoidable field errors affect the beam dynamics and worsen the slow extraction efficiency. Therefore, the field errors in the SIS300 dipoles have been estimated, and their effects have been taken into account in the optimization algorithm. As a result a compensation scheme has been proposed, in which time-dependent gradients in the sextupoles counteract the decay of the sextupole field errors in the dipole magnets during the slow extraction. For the limits where the compensation was no longer possible, tolerances to the magnet field errors have been determined.
From collective creativity to authorial primacy : Gottsched's reformation of the German theatre from a mediological point of view
- Theatre constitutes a form of collective creativity. This idea is not as self-evident as one might expect. To some extent the collective Character of this art form had to be rediscovered over the course of the twentieth century, as theatre emancipated itself from the primacy of the literary text and thus from the primacy of the author. In fact, the collective character of this art form was fully brought into view again only with the debates about a post-dramatic theatre of the last few decades. In this essay I will tum back to the point in cultural history when literature started to dominate theatre and when the supremacy accorded the author began to annul theatre's collective character. This paradigmatic shift in the evolution of theatre occurred during the eighteenth century, and it is represented primarily by Johann Christoph Gottsched. In the following I will investigate Gottsched's efforts to reform the theatre of his age from a mediological point of view.
The construction of masculinity in international relations
- International politics is characterized by a lack of women. The few women holding high political positions are more likely to be criticized and judged based upon, what the author calls, ‘the construction of masculinity in international relations’. Tracing the origin and logic of this construction, the article critiques the dominant theories of international relations (namely, realism and liberalism) and argues for the aptness of a radical feminist social constructivist approach to the study of international politics. The article also illuminates the strong focus on men and men’s perspectives of these influential mainstream theories on their conception and interpretation of war. An examination of the concept of war reveals how masculinity and femininity are portrayed on matters of war and national security and what side effects this has on women in politics, particularly women with political positions.
DNA damage in oocytes induces a switch of the quality control factor TAp63α from dimer to tetramer
Gregor B. Deutsch
Elisabeth M. Zielonka
Tobias A. Weber
Laura M. Luh
Florian G. Durst
Frank H. Niesen
- TAp63a, a homolog of the p53 tumor suppressor, is a quality control factor in the female germline. Remarkably, already undamaged oocytes express high levels of the protein, suggesting that TAp63a’s activity is under tight control of an inhibitory mechanism. Biochemical studies have proposed that inhibition requires the C-terminal transactivation inhibitory domain. However, the structural mechanism of TAp63a inhibition remains unknown. Here, we show that TAp63a is kept in an inactive dimeric state. We reveal that relief of inhibition leads to tetramer formation with ~20-fold higher DNA affinity. In vivo, phosphorylation-triggered tetramerization of TAp63a is not reversible by dephosphorylation. Furthermore, we show that a helix in the oligomerization domain of p63 is crucial for tetramer stabilization and competes with the transactivation domain for the same binding site. Our results demonstrate how TAp63a is inhibited by complex domain-domain interactions that provide the basis for regulating quality control in oocytes.
Diagnostic scheme for the HITRAP decelerator
Mircea Iuliu Ciobanu
Heinz Jürgen Kluge
- The HITRAP linear decelerator currently being set up at GSI will provide slow, few keV/u highly charged ions for atomic physics experiments. The expected beam intensity is up to 105 ions per shot. To optimize phase and amplitude of the RF systems intensity, bunch length and kinetic energy of the particles need to be monitored. The bunch length that we need to fit is about 2 ns, which is typically measured by capacitive pickups. However, they do not work for the low beam intensities that we face. We investigated the bunch length with a fast CVD diamond detector working in single particle counting mode. Averaging over 8 shots yields a clear, regular picture of the bunched beam. Energy measurements by capacitive pickups are limited by the presence of intense primary and partially decelerated beam and hence make tuning of the IH-structure impossible. The energy of the decelerated fraction of the beam behind the first deceleration cavity was determined to about 10 % accuracy with a permanent dipole magnet combined with a MCP. Better detector calibration should help reaching the required 1%. Design of the detectors as well as the results of the measurements will be presented.
First measurements with the test stand for optical beam tomography
- A test stand for optical beam tomography was developed. As a new non-destructive beam-diagnostic system for high current ion beams, the test stand will be installed in the low energy beam transport section (LEBT) of the Frankfurt Neutron Source (FRANZ) behind the chopper system. The test stand consists of a rotatable vacuum chamber with a mounted CCD camera. The maximum rotation angle amounts to 270°. In a first phase the optical beam profile measurement and 3D density reconstruction is tested with a time independent 10 keV He beam. The measurements and performance of data processing algorithms are compared with the beam transport simulations. In a later phase the performance with time dependent beams (120 keV, 200 mA) at a repetition rate of 250 kHz and a duty cycle of 2.5% has to be evaluated. An overview of the first phase results is shown.
New records of the olive ridley sea turtle Lepidochelys olivacea (Eschscholtz, 1829) from the Cape Verde Islands
Luis Felipe López-Jurado
- The olive ridley sea turtle Lepidochelys olivacea has been recorded in the Cape Verde Islands, but the most recent published data (1998-2000) are of stranded individuals and remains only. This article presents new data on olive ridleys recorded during the years 2001-2011 on Boavista and Sal islands. The presence of this species does not appear to be related to nesting activity. The possible geographical origin of these turtles is discussed. In addition, we propose some studies that could help to reinforce the conservation of sea turtles in West Africa.
Leiosolenus aristatus (Dillwyn, 1817), new to the Cape Verde Islands (Mollusca, Bivalvia, Mytilidae)
Evandro P. Lopes
- Leiosolenus aristatus (Dillwyn, 1817) is a small bivalve that pierces into calcareous substrata, particularly shells of other mollusks. Previously, the taxon has often been placed in Lithophaga Röding, 1798. It was then transferred to Myoforceps Fischer, 1886, which is now included in the synonymy of Leiosolenus Carpenter, 1856 (cf. Huber 2012).
Nesting activity of the loggerhead sea turtle Caretta caretta (Linnaeus, 1758) on Maio, Cape Verde Islands
- Loggerhead sea turtles Caretta caretta may now be the only species of marine turtle nesting on the island of Maio, Cape Verde Islands. Threats to loggerhead turtles include hunting of females on land and males and females in the water, poaching of nests and, increasingly, light pollution and other disturbances related to tourism development. Length and remoteness of the beaches on Maio lead to limited monitoring and data collection. Although it is believed that Maio has one of the largest nesting populations of loggerheads in the Cape Verde Islands, very little information exists regarding the nesting beaches and the population of nesting females. During July 2009, a four day survey of the island was carried out in order to obtain insight as to the status of nesting loggerheads on Maio. The census showed that compared to the island of Sal the number of turtles nesting on Maio was higher at 19.64% more nests and 39.9% more tracks during the same period. It is recommended that in order to determine the true size of the Maio nesting population a full census should be undertaken over several seasons.
An overview of the spider fauna of Maio (Cape Verde Islands), with some additional recent records (Arachnida, Araneae)
E. Geoffrey Hancock
Robert N. Kelsh
- Based on a collection of spiders obtained during ecological fieldwork in 2009 and an extensive literature review, we summarize the current state of knowledge of spider biodiversity on the island of Maio. The total number of species reported from Maio is now 46, representing 18 families and including 16 species (35%) endemic to the Cape Verde Islands. The family Dictynidae (meshweb spiders), represented by the saline-adapted Devade cf. indistincta, is reported for the first time from Cape Verde.