The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D [1]. One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop...

In this report, I address 4 different items: (1) the trapping of electrons in a quadrupole field, (2) the electron-cloud build up inside an HER dipole magnet, (3) the closed orbit drift with SVD correction, and (4) the transverse tune shifts and horizontal instability in the HER. The appendix presents preliminary electron-cloud simulations for the two JKJ rings. Geneva, Switzerland May 13, 2002...

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...

Electron cloud formation and the associated effects of beam loss and instabilities have been observed in high intensity proton machines such as the LANL PSR and the CERN SPS. A program has recently been launched at the Rutherford Appleton Laboratory (UK) to understand the lack of electron cloud induced instabilities in the operations of the 160 kW 70-800 MeV ISIS synchrotron. Simulations have b...

Measurements of the electron cloud effects in KEKB have been done since ECLOUD02 workshop. The results are summarized as 1) strength of the solenoid field in the present solenoid system is not enough to suppress the blow-up of the vertical beam size at high bunch currents and/or narrow bunch spacing, 2) solenoids in straight sections as well as arc sections contribute to suppress the electron c...

Recent simulation results and some analytical estimates are presented on beam-induced multipacting in SPS, PS, and LHC. In particular, we discuss modifications to the secondary emission model, electron cloud build up simulated for various filling patterns, central cloud density, electron ‘pinch’ during the bunch passage, expected tune shifts and tune spreads, memory between LHC bunch trains, he...

A series of new π-conjugated macrocycles (AzoM-n-E, n = 1–3) incorporating azobenzene units have been synthesized by a facile strategy in one-pot reaction. The resultant azobenzene-embedded feature intrinsic photoresponsive behaviors and intriguing supramolecular assembling properties. smallest macrocycle AzoM-1-E with rigid planar conjugated backbone structure is used to prepare the single cry...

We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire “ECLOUD” series [1–22]. In addition, the proceedings of the various flavors of Particle Accelerator Conferences [23] contai...

A Negishi coupling based synthesis of 1,2,4,5-tetra(9-anthryl)benzene derivatives, possessing X-shaped molecular structures, is described. The results X-ray crystallographic analysis show that two-dimensional highly ordered packing structure the crystalline state unsubstituted derivative a consequence intermolecular π-π and CH-π interactions between anthracene units. Photoirradiation as precipi...

Clearing electrodes have been successfully used to remove the ion from the vacuum chamber in many electron accelerators, especially in electron synchrotron light source. Electron cloud caused beam instabilities and vacuum pressure rise are becoming more and more important with the increasing beam intensity in recent years. In this paper we have explored the mechanism to clear the electron cloud...