59385487
Beam position monitor for the LNLS UVX synchrotron light source
The beam orbit measuring system for the LNLS UVX ring is presented. The system consists of 24 strip-line beam position monitors and associated electronics. The beam position monitors (BPM's) are capable of detecting down to 10 mA of stored beam current or 100 ns-long LINAC injection pulses (single pulse detection mode) with 0.05 mm resolution. Acquisition electronics is divided into two parts: four fast-acquisition channels for the pulsed mode operation (used during injection) and a single PIN-switch multiplexed channel for CW operation (closed orbit measurement). Experimental results obtained on a characterization bench are presented and compared with theoretical estimates.
55404585
STATUS OF THE 476 MHz 50 kW SOLID STATE AMPLIFIER FOR THE LNLS STORAGE RING
In November 2010, LNLS plans to replace the two 50 kW UHF klystron system which currently provides power to the RF cavities installed in the storage ring. To replace this system, two 50 kW solid state amplifiers have been built and are now under commissioning. Thanks to a close collaboration with the Synchrotron SOLEIL started in 1999, LNLS adapted the characteristics of the French project to 476 MHz. A short description of the amplifiers is presented, as well as the power tests performed with one of them using a resistive load.
18027030
Septum and kicker pulsers for the LNLS 500-MeV booster synchrotron
Brazilian National Synchrotron Light Laboratory (LNLS) has commissioned its new 500-MeV booster synchrotron injector. In this paper we present an overview of the septum and kicker pulse circuits now in operation. Half-sine wave septum current pulses range from 6.1 kA to 7.3 kA with widths around 80 /spl mu/s. Injection and extraction kicker circuits are capable of delivering currents up to 650 A and 1.2 kA, with fall and rise times consistent with the booster revolution period of 112 ns.
124098674
Search for new neutral gauge bosons in 1.8-TeV proton-antiproton collisions
64351367
Consumer server: A UNIX based event distributor in new CDF data acquisition system
Consumer Server is a program to handle event data and consumer trigger requests I/Os among Level 3 farm and consumer processes in CDF new data acquisition system. This program uses standard UNIX libraries and commercial network technologies to obtain higher portability. The authors describe the concept and configuration of the Consumer Server and report its performance.
14663098
Disk Galaxy Rotation Curves in Triaxial CDM Halos
We use N-body hydrodynamical simulations to study the structure of disks in triaxial potentials resembling CDM halos. Our analysis focuses on the accuracy of the dark mass distribution inferred from rotation curves derived from simulated long-slit spectra. We consider a massless disk embedded in a halo with axis ratios of 0.5:0.6:1.0 and with its rotation axis aligned with the minor axis of the halo. Closed orbits for the gaseous particles deviate from coplanar circular symmetry, resulting in a variety of long-slit rotation curve shapes, depending on the orientation of the disk relative to the line of sight. Rotation curves may thus differ significantly from the spherically-averaged circular velocity profile of the dark matter halo. "Solid-body" rotation curves--typically interpreted as a signature of a constant density core in the dark matter distribution--are obtained about 25% of the time for random orientations although the dark matter follows the cuspy density profile proposed by Navarro, Frenk & White (NFW). We conclude that the discrepancies reported between the shape of the rotation curve of low surface brightness galaxies and the structure of CDM halos may be resolved once the complex effects of halo triaxiality on the dynamics of the gas component is properly taken into account.
17908059
0 Numerical simulation of accretion discs in close binary systems and discovery of spiral shocks
The history of hydrodynamic numerical simulations for accretion disks in close binary systems is reviewed, in which emphasis is placed, in particular, on the facts that spiral shock waves were numerically found in 1986 by researchers including one of the present authors and that spiral structure was discovered in IP Pegasi in 1997 by Steeghs et al. The results of our two and three-dimensional numerical simulations in recent years are then summarized, with comparison being made with observations.
119460856
Is Angular Momentum in an Accretion Disk Transported Inwards
The derivation of the viscosity formula of accretion disks appearing in a number of textbooks is based on a mean free path theory of gas particles. However, this procedure, when followed precisely, leads to the incorrect conclusion that the angular momentum of an accretion disk flows from the outer part to the inner part.