Automatic beam steering in the CERN PS complex

The recombination, transfer and injection of the four beams from the PS Booster to the PS Main Ring, have a high level of intri-cacy and are a subject of permanent concern for the operation of the PS Injector Complex. These tasks were thus selected as a test bench for the implementation of a prototype of an auto-matic beam steering system. The core of the system is based on a generic trajectory optimizer, robust enough to cope with imper-fect observations. The algorithmic engine is connected to pick-up monitors and corrector magnets and its decision can be val-idated by the operator through a graphics user interface. Auto-matic beam steering can only be ef®cient if the beam optics is fully con®rmed by experimental observations, a conditionwhich forces the systematic elimination of errors both in hardware and software. I

Characterization of infectious and defective cloned avian hepadnavirus genomes

The infectivity in vivo, replication competence in vitro, and expression of viral genes of several molecularly cloned duck hepatitis B virus (DHBV) genomes were investigated. In addition, replication competence, core protein expression, and secretion of viral proteins were investigated for a grey heron hepatitis B virus genome. Except two, all DHBV isolates tested induced a systemic infection in Pekin ducks when injected as cloned viral DNA into the liver. After transfection of chicken hepatoma cells, both defective DHBV genomes expressed intracellular nucleocapsid and pre-S envelope proteins and secreted DHBs/pre-S particles into the medium. One of the defective DHBV genomes and HHBV produced within the cells replicative intermediates encapsidated in core particles and secreted virions, whereas the other defective DHBV genome did not and was unable to efficiently encapsidate the RNA pregenome. Comparative sequence analysis was performed to identify potential amino acid changes in viral proteins of both defective DHBV genomes. The data obtained demonstrate that most cloned avian hepadnaviruses are infectious or replication competent and suggest defects in envelope, polymerase or encapsidation function, respectively, in two cloned DHBV genomes

DISTINGUISHING BETWEEN SPOT AND TORUS MODELS OF HIGH-FREQUENCY QUASIPERIODIC OSCILLATIONS

In the context of high-frequency quasi-periodic oscillation (HF QPOs) we further explore the appearance of an observable signal generated by hot spots moving along quasi-elliptic trajectories close to the innermost stable circular orbit in the Schwarzschild spacetime. The aim of our investigation is to reveal whether observable characteristics of the Fourier power-spectral density can help us to distinguish between the two competing models, namely, the idea of bright spots orbiting on the surface of an accretion torus versus the scenario of intrinsic oscillations of the torus itself. We take the capabilities of the present observatories (represented by the Rossi X-ray Timing Explorer, RXTE) into account, and we also consider the proposed future instruments (represented here by the Large Observatory for X-ray Timing, LOFT)

Design Status of the CLIC 3-TeV Beam Delivery System and Damping Rings

We describe the present design status of beam delivery and damping rings for CLIC at 3 TeV cm energy, and outline our future plans. The beam delivery system comprises collimation, final focus and post-IP exit line. Critical design aspects include halo collimation, machine protection, beam removal, and thermal stability analysis. In order to attain the design spot size at the collision point, the damping rings must provide beams of extremely small emittances. In this paper, we focus on collimation and spent beam