The influence of a superconducting split-pair solenoid as an insertion device on the performance of a storage ring for synchrotron radiation

EINFLUSS EINES ALS INSERTION DEVICE VERWENDETEN SUPRALEITENDEN SPLIT-PAIR SOLENOIDEN AUF DAS VERHALTEN EINES SPEICHERRINGES FÜR SYNCHROTRONSTRAHLUNG Zur Erhöhung der Photonenenergie von Synchrotronstrahlungsquellen wird die Verwendung von starken nichtlinearen Magneten in Betracht gezogen. Solche Magnete können einen starken Einfluß auf die Funktion von Speicherringen ausüben, da sie die Emittanz vergrößern und die dynamische Apertur verringern können. In der vorliegenden Arbeit wird eine Methode vorgestellt, mit deren Hilfe der Einfluß der nichtlinearen Felder auf die dynamische Apertur berechnet werden kann. Mit dieser Methode wird die mögliche Auswirkung eines als Wellenlängenschieber eingesetzten kommerziellen 12 T Split-pair Solenoiden auf die dynamische Apertur der zukünftigen Synchrotronstrahlungsquelle ANKA untersucht

Localization of Human RNase Z Isoforms: Dual Nuclear/Mitochondrial Targeting of the ELAC2 Gene Product by Alternative Translation Initiation

RNase Z is an endonuclease responsible for the removal of 3′ extensions from tRNA precursors, an essential step in tRNA biogenesis. Human cells contain a long form (RNase ZL) encoded by ELAC2, and a short form (RNase ZS; ELAC1). We studied their subcellular localization by expression of proteins fused to green fluorescent protein. RNase ZS was found in the cytosol, whereas RNase ZL localized to the nucleus and mitochondria. We show that alternative translation initiation is responsible for the dual targeting of RNase ZL. Due to the unfavorable context of the first AUG of ELAC2, translation apparently also starts from the second AUG, whereby the mitochondrial targeting sequence is lost and the protein is instead routed to the nucleus. Our data suggest that RNase ZL is the enzyme involved in both, nuclear and mitochondrial tRNA 3′ end maturation

Generation of x-ray radiation in a storage ring by a superconductive cold-bore invacuum undulator

The first beam measurements with a cold-bore superconducting in-vacuum undulator in a storage ring are reported. Undulators are x-ray generators in light sources. The physical limitations of these devices limit the intensity and the brilliance of the x-ray beam. At present the undulators are made from permanent magnets. It was shown in earlier papers that at low electron beam intensities superconductive wires in the vacuum beam pipe can overcome the limitations inherent to permanent magnet undulators. It was argued that the use of these novel devices in light sources with high beam currents may be limited by the extreme anomalous skin effect regime in Cu at 4.2 K, which has so far undergone very little investigation, and the power deposited by the infrared part of the synchrotron radiation. The purpose of this paper is to present measurements of these effects at the synchrotron light source ANKA with stored currents up to 200 mA

A Laser Driven Grating Linac

The fields induced over a grating exposed to plane parallel light are explored. It is shown that acceleration is possible if either the particles travel skew to the grating lines, or if the radiation is falling at a skew angle onto the grating. A general theory of diffraction in this skew case is given. In one particular case numerical solutions are worked out for some deep grating. It is found that accelerating fields larger even than the initial fields can be obtained, the limit being set by resistive losses on the grating surface. Simple calculations are made to see what accelerating fields might be obtained using CO/sub 2/ lasers. Accelerations of 2 or 20 GeV per meter seem possible depending on whether the grating is allowed to be destroyed or not. Power requirements, injection and focussing are briefly discussed and no obvious difficulties are seen. It is concluded, therefore, that the proposed mechanism should be considered as a good candidate for the next generation of particle accelerators