| Paper | Title | Page |
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| MPPE065 | Fully Coupled Analysis of Orbit Response Matrices at the FNAL Tevatron | 3662 |
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38, and by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U.S. Dept. of Energy. Optics measurements have played an important role in improving the performance of the FNAL Tevatron collider. Initial optics measurements were performed using a small number of differential orbits, which allowed us to carry out the first round of optics corrections. However, because of insufficient accuracy, it was decided to apply the response matrix analysis method for further optics improvements. The response matrix program developed at ANL has been expanded to include coupling – the essential feature required to describe the Tevatron optics. The results of the optics calibration are presented and compared to local beta function measurements. |
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| MPPP042 | Landau Damping of the Weak Head-Tail Instability at Tevatron | 2714 |
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| Landau damping of the head-tail modes in Tevatron beam with the help of octupole-generated betatron tune spreads permits to reduce chromaticity from 15-20 units to zero thus significantly improving the beam lifetime. The octupole strengths have been experimentally optimized at different stages of the Tevatron operation, from proton injection to collision. Predictions of the analytical Landau damping model are compared with the experimental results. | ||
| MPPP043 | Betatron Tune Spread Generation and Differential Chromaticity Control by Octupole at Tevatron | 2756 |
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| Application of octupoles for Landau damping of the unstable head-tail modes requires careful consideration at their combination into separate families to insure maximum effectiveness and avoid degradation of the dynamic aperture due to the non-linear magnetic fields. Existing octupolar magnets around the machine have been arranged into four functional families with individual power supplies. Two of these families generate betatron tune spreads in the vertical and horizontal planes whereas the other two control the differential chromaticity between the proton and antiproton helices. The calculated effect on tunes and chromaticity is compared with direct measurements. Analytical formulas for betatron tune spectral density functions are presented. | ||
| 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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| TPAT083 | Computational Study of the Beam-Beam Effect in Tevatron Using the LIFETRAC Code | 4117 |
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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. Results of a comprehensive numerical study of the beam-beam effect in the Tevatron are presented including the dependence of the luminosity lifetime on the tunes, chromaticity and optics errors. These results help to understand the antiproton emittance blow-up routinely observed in the Tevatron after the beams are brought into collision. To predict a long term luminosity evolution, the diffusion rates are increased to represent long operation time (~day) by using a small number of simulated turns. To justify this approach, a special simulation study of interplay between nonlinear beam-beam resonances and diffusion has been conducted. A number of ways to mitigate the beam-beam effects are discussed, such as increasing bunch spacing, separation between the beams and beam-beam compensation with electron lenses. |
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| TPAT084 | LIFETRAC Code for the Weak-Strong Simulation of the Beam-Beam Effect in Tevatron | 4138 |
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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. A package of programs for weak-strong simulation of beam-beam effects in hadron colliders is described. Accelerator optics parameters relevant to the simulation are derived from beam measurements and calculations are made using OptiM optics code. The key part of the package is the upgraded version of the LIFETRAC code which now includes 2D coupled optics, chromatic modulation of beta-functions, non-Gaussian shape of the strong bunches and non-linear elements for beam-beam compensation. Parallel computations are used and in the case of the Tevatron (2 main IPs + 70 parasitic IPs) the code has a productivity of ~1·1010 particles*turns/day on a 32-node cluster of Pentium IV 1.8 GHz processors. |