Superconducting versus normal conducting cavities

One of the most important issues of high-power hadron linacs is the choice of technology with respect to superconducting or room-temperature operation. The favour for a specific technology depends on several parameters such as the beam energy, beam current, beam power and duty factor. This contribution gives an overview of the comparison between superconducting and normal conducting cavities. This includes basic radiofrequency (RF) parameters, design criteria, limitations, required RF and plug power as well as case studies.Comment: 20 pages, contribution to the CAS - CERN Accelerator School: Course on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai

Frequency Jump at Low Energies

One or more radio-frequency jumps are usually necessary for realizing a >= 100 AMeV/u proton or ion driver linac. Typically, such jumps happen in the range of \b{eta} = 0.2-0.6 between the resonator structures fitting to this \b{eta}-range, e.g. DTL, HWR, CCL or elliptical cavities. We propose to perform the first frequency jump already at low energies (\b{eta} <= 0.1) between two RFQ accelerators, which can bring some unique advantages. First studies have been performed and the results proved that this idea is feasible and promising. Many efforts have been and are being made to address the most critical issue for the jumps i.e. the beam matching at the transition

Die Auswirkungen des Steuersystemwechsels vom Halbeinkünfteverfahren zur Abgeltungssteuer auf die Ausschüttungspolitik von Unternehmen

Mit der Einführung der Abgeltungsteuer zum 1. Januar 2009 hat sich die Besteuerung von Einkünften aus Kapitalbeteiligungen in Deutschland grundlegend verändert. In diesem Beitrag wird analysiert, welche Auswirkungen der Steuersystemwechsel vom Halbeinkünfteverfahren zur Abgeltungssteuer auf die Ausschüttungspolitik von Unternehmen hat. Zu diesem Zweck werden die Vermögenspositionen von Aktionären eines Unternehmens betrachtet, welches liquide Mittel entweder in Form einer Dividende oder in Form eines Aktienrückkaufes ausschüttet, oder diese Mittel alternativ für eine Investition einbehält. Auf der Grundlage dieser Vermögenspositionen werden anschließend für beide Steuersysteme die kritischen Werte für die Rendite einer zusätzlichen Investition bei Einbehaltung abgeleitet und miteinander verglichen. Dabei stellt sich heraus, dass nach dem Steuersystemwechsel Unternehmen im Interesse des Großteils ihrer Aktionäre auf Investitionsprojekte verzichten sollten, die das Vermögen der Aktionäre unter dem Halbeinkünfteverfahren noch gesteigert haben. Anstatt in diese Projekte zu investieren ist den Unternehmen heute angeraten diese Mittel auszuschütten.Since January 1, 2009 capital gains on equity participations are taxable with a flat tax rate in Germany. This paper examines the impact of the tax system change on the payout policy of corporations. For this purpose the shareholder wealth is examined if the corporation pays out free cash in the form of a dividend or share repurchase or alternatively retains the funds for a company-internal investment. The results suggest that in the interest of most of its shareholders corporations should no longer invest in all projects that were beneficial under the previous tax system. Instead the corporations should pay out these funds

Synthesis of Octahydroperylene, the Framework of Altertoxin III

Routes to the framework of perylenequinone-derived mycotox- ins of the dihydroanthracene type are described. Starting with anthracene derivatives, attachment of C3 units at positions 9 and 10 and twofold cyclization would furnish the required pentacycle. Heck-type couplings, S$_N$2 additions of enolates, alkynyl and allyl additions turned out to be not successful, while addition of a Grignard reagent prepared from acetal-protected 3-bromopropionaldehyde to anthraflavic acid methyl ester, subsequent acetal cleavage, and Birch reduction furnished octahydroperylene in only four steps

Oxidation of Dithia Compounds: Comparative Experimental and Theoretical Studies on 1,3 Bis(methylthio)propane, Bis(methylthio)methane, and Theoretical Studies on 1,3-Bis(methylthio)propane, Bis(methylthio)methane, and meso-4,6-Dimethyl-1,3-dithiane

1,3-Bis(methylthio)propane, bis(methylthio)methane, and meso-4,6-dimethyl-1,3-dithiane were oxidized with 1–4 equivalents of hydrogen peroxide, meta-chloroperbenzoic acid, sodium periodate, or potassium permanganate, respectively, and the amounts of oxidized substrates (sulfoxides and/or sulfones) were determined by NMR spectroscopy. Sulfanyl groups in the former starting material turned out to behave like independent functions, while a mutual influence of the sulfur functions was verified in the latter compounds. A meaningful investigation was possible in the conformationally constrained dithiane derivative. Oxidation of the dithiane with stoichiometric amounts of periodate led to exclusive formation of bissulfoxides, while hydrogen peroxide and meta-chloroperbenzoic acid yielded the possible products less specifically and permanganate preferentially furnished sulfones. The experimental investigations were supported by calculations on energies and stereoelectronic effects of starting materials, products, and transition states. The unique property of permanganate to exclusively yield sulfones might be due to its special oxidation mechanism, where the sulfur is not only acting as nucleophile, but concomitantly as electrophilic moiety