| Paper | Title | Page |
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| THPMN104 | Recent Studies of Dispersion Matched Steering for the ILC Bunch Compressor and Main Linac | 2954 |
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| Beam Based Alignment techniques are expected to play a critical role to the emittance preservation for the ILC. The Dispersion Free Steering (DFS) method is studied in detail in the 2nd statge of the bunch Compressor and in the beginning of the curved Main Linac. It is shown than in absence of cavity tilts (rotations on the YZ plane), DMS provides a unique and stable solution with negligible emittance growth. If cavity tilts are about 200 to 300 micro-radiant, the DMS solution is no longer unique and significant emittance occurs as well. While within the ILC budget, other dynamical effects, such a large beam jitter or sudden ground motion will cause severe performance degradation. A Variant of the DFS algorithm can be used to re-aling cavity supports, leading to better LET performance. In presence of perturbations (klystron jitter, ground motion,.. ) such DFS solutions are easier to maintain and improved if they are stable and unique. Therefore, it is suggested to consider using movers on quadrupole/BPM and, a bit more controversial, for the support system of the r.f. cavities, especially at low energy, where spurious dispersion due to cavity tilts are large. | ||
| THPAN112 | CHEF: A Status Report | 3486 |
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Funding: Authored by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Department of Energy. CHEF is both a framework and an interactive application emphasizing accelerator optics calculations. The framework supports, using a common infrastructure, multiple domains of applications: e.g. nonlinear analysis, perturbation theory, and tracking. Its underlying philosophy is to provide infrastructure with minimum hidden implicit assumptions, general enough to facilitate both routine and specialized computational tasks and to minimize duplication of necessary, complex bookkeeping tasks. CHEF was already described in recent conferences. In this paper we present a status report on the most recent developments, including issues related to its application to high energy linacs. |
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| THPAN113 | Mxyzptlk: An Efficient, Native C++ Differentiation Engine | 3489 |
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Funding: Authored by Universities Research Association, Inc. under contract No. DE-AC02-76CH03000 with the U. S. Department of Energy. Mxyzptlk was one of the early and, to this day, limited number of differentiation engines implemented by taking full advantage of a language with operator overloading capabilities. It was created with an eye at enabling accelerator related computations, especially within the realm of perturbation theories. Such computations are supported by (1) a one-to-one correspondence between original mathematical abstractions and the data types and operations used to implement them; (2) the exact computation of high order derivatives. Significant efforts were invested recently in modernizing Mxyzptlk both architecturally and algorithmically. Among other things, these substantially improved performance and usabilty. We present a description of the current Mxyzptlk from both standpoints and describe its current capabilities and performance. |
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| THPAN117 | Electron Cloud Studies at Tevatron and Main Injector | 3501 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000 Estimates indicate that the electron cloud effect could be a limiting factor for Main Injector intensity upgrades, with or without a the presence of a new 8 GeV superconducting 8GeV Linac injector. The effect may turn out to be an issue of operational relevance for other parts of the Fermilab accelerator complex as well. To improve our understanding of the situation, two sections of specially made vacuum test pipe outfitted for electron cloud detection with ANL provided Retarding Field Analyzers (RFAs), were installed in the Tevatron and the Main Injector. In this report we present some measurements, compare them with simulations and discuss future plans for studies. |
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| THPAN118 | Simulations of the Electron Cloud Buildups and Suppressions in Tevatron and Main Injector | 3504 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000 To assess the effects of the electron cloud on Main Injector intensity upgrades, simulations of the cloud buildup were carried out using POSINST and compared with ECLOUD. Results indicate that even assuming an optimistic 1.3 maximum secondary electron yield, the electron cloud remains a serious concern for the planned future operational of mode of 500 bunches, 3·1011 proton per bunch. Electron cloud buildup can be mitigated in various ways. We consider a plausible scenario involving solenoids in straight section and a single clearing strip electrode (like SNEG in Tevatron)held at a potential of 500V. Simulations with parameters corresponding to Tevatron and Main Injector operating conditions at locations where special electron cloud detectors have been installed have been carried out and are in satisfactory agreement with preliminary measurements. |