| Paper | Title | Page |
|---|---|---|
| MOPC006 | Simulations and Experiments of Beam-Beam Effects in e+e- Storage Rings | 520 |
|
||
|
Funding: Work partially supported by the Department of Energy under Contract No. DE-AC02-76SF00515. Over the past decade, extensive simulations of beam-beam effects in positron-electron collliders, based on the particle-in-cell method, were developed to explain many complex experimental observations. Recently, such simulations were used to predict the future luminosity performance of e+e- colliders. Some predictions have been proven to be correct in the existing accelerators. In this paper, many effects such as dynamic beta, beam-beam limit, crossing angle, parasitic collisions, betatron spectrum, and beam-beam lifetime, will be reviewed from the viewpoints of both simulation and experiment. Whenever possible, direct comparisons between the predictions of the simulation and the corresponding experimental results will be provided. |
||
| MPPE025 | Dynamical Effects Due to Fringe Field of the Magnets in Circular Accelerators | 1907 |
|
||
|
Funding: Work supported by the Department of Energy under Contract No. DE-AC02-76SF00515. The leading Lie generators, including the chromatic effects, due to hard edge fringe field of single multipole and solenoid are derived from the vector potentials within a Halmitonian system. These nonlinear generators are applied to the interaction region of PEP-II to analyze the linear errors due to the feed-down from the off-centered quadrupoles and solenoid. The nonlinear effects of tune shifts at large amplitude, the synchro-betatron sidebands near half integer and their impacts on the dynamic aperture are studied in the paper. |
||
| MPPE058 | Virtual Accelerator for Accelerator Optics Improvement | 3426 |
|
||
|
Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling eigen-plane ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and linear coupling reduction to improve PEP-II luminosity. |
||
| MPPE059 | Precision Measurement of Coupling Ellipses Parameters in a Storage Ring | 3459 |
|
||
|
Funding: Work supported by Department of Energy contract DE-AC02-76SF00515. Eigen-mode coupling ellipses' tilt angles and axis ratios can be precisely measured with a Model-Independent Analysis (MIA) of the turn-by-turn BPM data from resonance excitation of the betatron motion. For each BPM location one can measure 4 parameters from the two resonance excitation, which completely describe the linear coupling of the location. Results from application to PEP-II storage rings are presented. |
||
| TPAT072 | Long-Term Simulation of Beam-Beam Effects in the Tevatron at Collision Energy | 3871 |
|
||
|
The weak-strong beam-beam effect is expected substantially to contribute to the degradation of beam lifetimes in the Tevatron at collision energy. We have expanded an existing multi-processor code (which previously was applied to the Tevatron at injection energy* to include chromatic and non-linear lattice effects as well as a fully-coupled treatment of the lattice in different approximations.** We obtain lifetime predictions by doing temporal statistics on the tracking results of a weighted macroparticle distribution and fitting it to a class of solutions for the diffusion equation. We present typical results of parameter scans.
*A. Kabel, Y. Cai, B. Erdelyi, T. Sen, M. Xiao; Proceedings of PAC03. **A. Kabel, this Conference. |
||
| TPAT077 | Beam-Beam Study on the Upgrade of Beijing Electron Positron Collider | 4000 |
|
||
| It is an important issue to study the beam-beam interaction in the design and performance of such a high luminosity collider as BEPCII, the upgrade of Beijing Electron Positron Collider. The weak-strong simulation is generally used during the design of a collider. For performance a large scale tune scan, the weak-strong simulation studies on beam-beam interaction were done, and the geometry effects were taken into account The strong-strong simulation studies were done for investigating the luminosity goal and the dependence of the luminosity on the beam parameters. | ||
| TPPP024 | Experimental Study of Crossing-Angle and Parasitic-Crossing Effects at the PEP-II e+e- Collider | 1874 |
|
||
| In a series of dedicated accelerator experiments, we have measured the dependence of the PEP-II luminosity performance on small horizontal crossing angles and on the horizontal separation at the first parasitic crossing. The experiment was carried out by varying the IP angle of one of the beams in two different bunch patterns, one with and one without parasitic crossings. The experimental measurements show satisfactory agreement with three-dimensional beam-beam simulations. | ||
| TPPP034 | Parameters of a Super-B-Factory Design | 2333 |
|
||
|
Funding: Work supported by DOE contract DE-AC02-76SF00515. Submitted for the High Luminosity Study Group: Parameters are being studied for a high luminosity e+e- collider operating at the Upsilon 4S that would deliver a luminosity in the range of 7 to 10 x 1035/cm2/s. Particle physics studies dictate that a much higher luminosity collider is needed to answer new key physics questions. A Super-B-Factory with 20 to 100 times the performance of the present PEP-II accelerator would incorporate a higher frequency RF system, lower impedance vacuum chambers, higher power synchrotron radiation absorbers, and stronger bunch-by-bunch feedback systems. Parameter optimizations are discussed. |
||
| TPPP035 | Performance of the PEP-II B-Factory Collider at SLAC | 2369 |
|
||
|
Funding: Work supported by DOE contract DE-AC02-76SF00515. For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has reached 9.2 x 1033/cm2/s. PEP-II has delivered an integrated luminosity of 710/pb in one day. It operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 2.55 A in 1588 bunches. The total integrated luminosity since turn on in 1999 has reached 256/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s. Upgrade details and plans are discussed. |
||
| RPPP054 | Achieving Large Dynamic Aperture in the ILC Damping Rings | 3277 |
|
||
|
Funding: Work supported by US Department of Energy, Director, Office of Science - Contract Nos. DE-AC03-76SF00098 and DE-AC03-76SF00515. The Damping Rings for the International Linear Collider have challenging requirements for the acceptance, because of the high average injected beam power and the large beam produced from the positron source. At the same time, the luminosity goals of the collider mean that the natural emittance must be very small, and this makes it particularly difficult to achieve a good dynamic aperture. We describe a design approach and present a lattice design that meets the emittance specification and has a very promising dynamic aperture. We also discuss the potential impact of the damping wiggler and of magnet errors. |