Analog electronics for beam instrumentation

The task of analog front-end electronics in beam instrumentation is to optimize the useful information content of the signal delivered by an instrument. It must suppress signal components that do not contribute to the measured quantity. It must filter to put bounds on bandwidth and possibly dynamic range, to relax the demands made of subsequent processing stages. It must minimize noise, reject interference and match the signal to transmission media and digital acquisition equipment. Since the circuitry must often operate in radio-active areas, the accent is on passive electronics.Comment: 27 pages, 60 figure

High Performance Direct Gravitational N-body Simulations on Graphics Processing Units -- II: An implementation in CUDA

We present the results of gravitational direct $N$-body simulations using the Graphics Processing Unit (GPU) on a commercial NVIDIA GeForce 8800GTX designed for gaming computers. The force evaluation of the $N$-body problem is implemented in ``Compute Unified Device Architecture'' (CUDA) using the GPU to speed-up the calculations. We tested the implementation on three different $N$-body codes: two direct $N$-body integration codes, using the 4th order predictor-corrector Hermite integrator with block time-steps, and one Barnes-Hut treecode, which uses a 2nd order leapfrog integration scheme. The integration of the equations of motions for all codes is performed on the host CPU. We find that for $N > 512$ particles the GPU outperforms the GRAPE-6Af, if some softening in the force calculation is accepted. Without softening and for very small integration time steps the GRAPE still outperforms the GPU. We conclude that modern GPUs offer an attractive alternative to GRAPE-6Af special purpose hardware. Using the same time-step criterion, the total energy of the $N$-body system was conserved better than to one in $10^6$ on the GPU, only about an order of magnitude worse than obtained with GRAPE-6Af. For N \apgt 10^5 the 8800GTX outperforms the host CPU by a factor of about 100 and runs at about the same speed as the GRAPE-6Af.Comment: Accepted for publication in New Astronom

A sparse octree gravitational N-body code that runs entirely on the GPU processor

We present parallel algorithms for constructing and traversing sparse octrees on graphics processing units (GPUs). The algorithms are based on parallel-scan and sort methods. To test the performance and feasibility, we implemented them in CUDA in the form of a gravitational tree-code which completely runs on the GPU.(The code is publicly available at: http://castle.strw.leidenuniv.nl/software.html) The tree construction and traverse algorithms are portable to many-core devices which have support for CUDA or OpenCL programming languages. The gravitational tree-code outperforms tuned CPU code during the tree-construction and shows a performance improvement of more than a factor 20 overall, resulting in a processing rate of more than 2.8 million particles per second.Comment: Accepted version. Published in Journal of Computational Physics. 35 pages, 12 figures, single colum

A proposal for a trajectory measurement system for the PS Booster

This is a proposal to equip the CERN PS Booster with a trajectory measurement system along the same lines as was previously done for the PS. That is, high-speed ADCs convert all BPM signals directly into the digital domain at a high rate, and individual bunch positions as well as averaged orbits are calculated on the fly and stored into a large circular buffer memory. Multiple users may then read the data they are interested in. The system will make use of modern fast ADCs, large FPGAs and SDRAM

A New Wall Current Monitor for the CERN Proton Synchrotron

Wall Current Monitors are the devices of choice to observe the instantaneous beam current in proton accelerators. These entirely passive transformers deliver a high-fidelity image of the beam intensity in a bandwidth spanning from about 100kHz up to several GHz. They serve as a signal source for a diverse set of applications including Low Level RF feedback and longitudinal diagnostics such as bunch shape measurements and phase-space tomography. They are appreciated for their excellent reliability, large bandwidth and unsurpassed dynamic range. We describe the design of a new Wall Current Monitor for the CERN Proton Synchrotron with a useful bandwidth of 100kHz to 4GHz. Two such devices have been installed in the PS machine and are now used in regular operation. Some usage examples will be shown