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| MOPC009 | Experiments on LHC Long-Range Beam-Beam Compensation and Crossing Schemes at the CERN SPS in 2004 | 686 |
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| Experiments with two prototype long-range beam-beam compensators (current-carrying wires) during the 2004 CERN SPS run explored the efficiency of a proposed long-range beam-beam compensation for the LHC. In addition, the SPS compensators were also used to 'simulate' the effect of different planes of crossing at two LHC interaction points. We present the experimental results and compare them with computer simulations. | ||
| TPAP026 | Improving the Tevatron Collision Helix | 1931 |
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| In the Tevatron, protons and pbars circulate in a single beam pipe, so electrostatic separators are used to create helical orbits that separate the two beams except at the two interaction points (IP). Increasing the separation outside of the IPs is desirable in order to decrease long range beam-beam effects during high energy physics (HEP) stores. We can increase separation by running the separators at higher gradients or by installing additional separators. We are pursuing both strategies in parallel. Here, we describe Tevatron operation with higher separator gradients and with new separators installed during a recent shutdown. We also describe possible future improvements. | ||
| TPAP028 | Observations of Strong Transverse Coupling in the Tevatron | 2029 |
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Funding: United States Department of Energy under Contract No. DE-AC02-76CH03000. During the beginning of Run II of the Tevatron Collider it became apparent that a large skew quadrupole source, or sources, had developed in the superconducting synchrotron. Efforts to locate the current source of coupling were undertaken, with the eventual discovery that the main magnets had developed a systematic skew quadrupole moment over their lifetime. Over the past year, the magnets have been altered in place in an attempt to restore the systematic skew quadrupole moment to zero. Beam observations and their interpretations are presented, and remedial measures are discussed. |
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| TPAP032 | Beam-beam Effects in the Tevatron Run II | 2245 |
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Funding: Work supported by the Universities Research Assos., Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. The Tevatron in Collider Run II (2001-present) is operating with many times higher beam intensities and luminosities than in previous Run I (1992-1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in operations, predict the performance at upgraded beam parameters and luminosity and discuss possible improvements. |
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| TPAP040 | Feasibility Study of Beam-Beam Compensation in the Tevatron with Wires | 2645 |
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Funding: Dept. of Energy. At large distances the field profile of a current carrying wire matches the profile of the field of a round beam. We consider the practical applicability of this principle in compensating long-range beam-beam effects in the Tevatron. Changes in the helix and beam separation from injection energy to collision energy require that different wire configurations at these different energies. Due to the seventy or more long-range interactions, each set of wires must compensate several interactions. We first develop the principles of non-local compensation with a small set of wires. Next we use these principles in detailed simulation studies with beam-beam interactions and wire fields to determine the feasibility of the compensation in the Tevatron. |
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| TPAT072 | Long-Term Simulation of Beam-Beam Effects in the Tevatron at Collision Energy | 3871 |
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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. |
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| FPAT005 | A Betatron Tune Fitting Package for the Tevatron 21.4 MHz Schottky | 937 |
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| Accurate control of the Betatron tunes and chromaticities is required to optimize the dynamical aperture of any large synchrotron. The Fermilab Tevatron is equipped with two independent Schottky monitors, one operating at 21.4 MHz and the other 1.7 GHz. While the latter one allows us to characterize individual bunches separated by 396 ns, the former one has a larger Q and can give precise tune measurements. A new front-end and related data acquisition for this 21.4 MHz resonator has been installed and commissioned during the FY04 Collider RunII. Output signal are digitized at 100 KHz. Frequency spectra are transfered to dedicated server nodes and fitted in real time. Such frequency spectra are quite complex, due to inherent noise, horizontal/vertical coupling and synchrotron motion. Sophisticated fitting strategies are required. Optimization of this fitting package on relatively powerful commodity computer allows us to report tune and chromaticity measurements at almost 1 Hz. The architecture of the data acquisition system and this fitting package are described and results taken during the FY04 and FY05 runs are presented. |