121301-1 The focusing effects of a 1.4 m long, 0–2 1014 cm 3 plasma on a single 28.5 GeVelectron bunch are studied experimentally in the underdense or blowout regime, where the beam density is much greater than the plasma density. As the beam propagates through the plasma, the density of plasma electrons along the incoming bunch drops from the ambient density to zero leaving a pure ion channel ...

A tunable energy-chirp compensator was used to remove a correlated energy chirp from the 60-MeV beam at the Brookhaven National Laboratory Accelerator Test Facility. The compensator operates through the interaction of the wakefield of the electron bunch with itself and consists of a planar structure comprised of two alumina bars with copper-plated backs separated by an adjustable beam aperture....

When a proton bunch passes by, electrons which are in the chamber will gain some energy due to the passage of this bunch. This report presents approximate formulas, valid in the absence of an external magnetic field, for the total energy gained by a test charge from a relativistic beam as a function of the initial radial position of the particle. These formulas are used to estimate the total en...

This paper describes basic steps of a new technique, called bunch sampling, that allows to realistically synthesise spatially homogeneous textures. A geometric shape of the bunch (acting as a texel) and spatial placement grid governing relative positions of the bunches are estimated from the training texture by using a generic Gibbs random field texture model with multiple pairwise pixel intera...

This paper describes the basic steps of a new technique, called bunch sampling, that enables the realistic synthesis of spatially homogeneous textures. A geometric shape of the bunch (acting as a texel) and spatial placement grid governing relative positions of the bunches are estimated from the training texture by using a generic Gibbs random field texture model with multiple pairwise pixel in...

Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transv...

A new method of monitoring the luminosity has been developed at CESR. The method involves shaking one bunch at a speciic frequency and observing the resulting oscillations of the corresponding opposing bunch. In initial tests, measurements with 1% accuracy have been obtained in 1 second. Measurements of diierent bunches in a train shows bunch to bunch diierences with the optimum luminosity cond...

In this paper, the performance of the emerging Switched Bunch Of Disks (SBOD) RAID architecture is compared to the more traditional Managed Bunch Of Disks (MBOD) using both analytical and simulation models. The benchmark used for this comparison is the conventional IOmeter that enables Throughput and IOPS of these systems to be compared. The SBOD configuration that maximises its performance is ...

The head-tail instability caused by an electron cloud in positron storage rings is studied numerically using a simple model. In the model, the positron beam is longitudinally divided into many slices that have a fixed transverse size. The centroid of each slice evolves dynamically according to the interaction with a two-dimensional electron cloud at a given azimuthal location in the ring and a ...