| Paper | Title | Page |
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| MOPA010 | Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron | 725 |
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| Chromaticity drift is a well-known and more or less well-understood phenomenon in superconducting colliders such as the Tevatron. Less known is the effect of tune and coupling drift, also observed in the Tevatron during injection. These effects are caused by field drifts in the superconducting magnets. Understanding of the behavior of the tune, coupling, and chromaticity at the start of the ramp is an important part of understanding the observed 5-10% loss in beam intensity at the start of the Tevatron ramp. In addition modifications in the Tevatron shot set-up procedure are being implemented to allow for a gain in integrated luminosity. In this context we conducted several beam-studies, during the period of April to August 2004, in which we measured the drift in the Tevatron chromaticity, tune and coupling during the injection porch. In some case we also measured the snapback at the start of the ramp. We will present the results of these studies data and put them into context of the results of off-line magnetic measurements conducted in spare Tevatron dipoles at the same time. Finally we will propose optimized feed-forward algorithms that successfully compensate for the drift effects in the Tevatron. | ||
| 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. | ||
| TPAP030 | Tevatron Alignment Issues 2003-2004 | 2146 |
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Funding: U.S. Department of Energy under contract No. DE-AC02-76CH03000. It was observed during the early part of Run II that dipole corrector currents in the Tevatron were changing over time. Measurement of the roll for dipoles and quadrupoles confirmed that there was a slow and systematic movement of the magnets from their ideal position. A simple system using a digital protractor and laptop computer was developed to allow roll measurements of all dipoles and quadrupoles. These measurements showed that many magnets in the Tevatron had rolled more than 1 milli-radian. To aid in magnet alignment a new survey network was built in the Tevatron tunnel. This network is based on the use of free centering laser tracker. During the measurement of the network coordinates for all dipole, quadrupole and corrector magnets were obtained. This paper discusses roll measurement techniques and data, the old and new Tevatron alignment network. |