This paper presents recent observations obtained on the study of electron cloud induced instabilities and emittance growth on positron beams at the Cornell Electron-Positron Storage Ring Test Acceleartor (CesrTA), and the simulation of these phenomena under similar beam conditions using the program CMAD. Results show that the transition to large bunch oscillations ocurrs at similar electron clo...

comparison and grouping of 32 grape cultivars and genotypes by using 61 traits including; 5 phenological and vegetative characters, 41 traits related to fruit and amount of resveratrol in 15 parts of plant was done according to grape descriptor and related methods. according to the results some traits such as spikelet weight, berry color, length of peduncle, length of berry tail, weight and len...

We have studied fast ion instability (FII) in the electron ring (HER) at KEKB. We introduce an application of Singular Value Decomposition (SVD) to study multi-bunch beam oscillations. The SVD analysis[1] has been performed for a matrix consists of vertical bunch positions in a turn-byturn and bunch-by-bunch to extract wave lengths which characterized the behavior of multi-bunch beam instabilit...

With the high intensity, low emittance beams needed to reach the luminosity goals of the linear collider, beam size monitoring will play an important role in machine operation. In the damping rings synchrotron radiation (SR) emitted by the bunch can provide a means of measuring transverse bunch size and shape. With suitable imaging and high speed detection of the SR, bunch size, shape, and posi...

A low energy electron beam can be used to characterize the high energy ultra-relativistic bunches. This technique allows one to obtain the bunch transverse profiles as well as the bunch length within a non-destructive single shot measurement. In this paper the bunch length measurement technique based on the interaction of the low energy electron beam with an ultra-relativistic bunch is describe...

As the beam currents at the SLC are increased, transverse aperture restrictions in the ring-to-linac transport line (RTL) become increasingly important. The RTL contains a bunch compressor which introduces a large energy variation across the bunch and hence a larger transverse beam size. Since 1994 the compressor amplitude has been operating at higher than design voltage. While advantangeous fo...

In order to study the wakefield effects of an electron cloud, a test bunch was placed behind a bunch train, where the cloud density rapidly varied. A currentdependent tune shift and the tune spread of the test bunch were measured as a function of the bunch current while varying the bucket position of the test bunch. The vertical tune shift indicated a strong defocusing force together with a wid...

In order to investigate the single-beam vertical beam-size blow-up observed[1] in the KEKB 3.5 GeV positron ring (LER), we performed beam-size observations using a highspeed gated camera capable of recording the image of a single bunch in the ring. Using this technique, we measured the beam-size dependence on bunch position along a train, and studied the onset of blow-up under various condition...

In a final-focus system, space-charge forces can be significant even for very high beam energies. The reason is the inherent large chromaticity of such a system, which needs to be compensated to a high precision. The longitudinal space-charge force causes an energy variation along the bunch, which depends on beam size, beam-pipe radius, and bunch population. Since this energy variation is locat...

The proposed PEP II B factory at SLAC requires a feedback to damp out longitudinal synchrotron oscillations. A time domain, downsampled, bunch-by-bunch feedback system in which each bunch is treated as an oscillator being driven by disturbances from other bunches is presented as we review the evolution of the system design. Results from a synchrotron oscillation damping experiment conducted at ...