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| MOOCH01 |
Beam Based Alignment at the KEK-ATF Damping Ring
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36 |
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- M. Woodley, J. Nelson, M.C. Ross, J.L. Turner
SLAC, Menlo Park, California
- K. Kubo
KEK, Ibaraki
- A. Wolski
LBNL/AFR, Berkeley, California
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The damping rings for a future linear collider will have demanding alignment and stability requirements in order to achieve the low vertical emittance necessary for high luminosity. The Accelerator Test Facility (ATF) at KEK has successfully demonstrated the <5 pm vertical emittance specified for the GLC/NLC Main Damping Rings [*]. One contribution to this accomplishment has been the use of Beam Based Alignment (BBA) techniques. The mode of operation of the ATF presents particular challenges for BBA, and we describe here how we have deduced the offsets of the BPMs with respect to the quadrupoles. We also discuss a technique that allows for direct measurements of the beam-to-quad offsets.
* "Extremely Low Vertical-Emittance Beam in the Accelerator Test Facility at KEK", K. Kubo, et al., Phys.Rev.Lett.88:194801,2002
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Video of talk
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Transparencies
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| MOOCH03 |
Status of a Linac RF Unit Demonstration for the NLC/GLC X-band Linear Collider
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42 |
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- D.C. Schultz, C. Adolphsen, D.L. Burke, J. Chan, S. Doebert, V.A. Dolgashev, J.C. Frisch, R.K. Jobe, D.J. McCormick, C.D. Nantista, J. Nelson, M.C. Ross, T.J. Smith, S.G. Tantawi
SLAC, Menlo Park, California
- D.P. Atkinson
LLNL, Livermore, California
- Y.H. Chin, S. Kazakov, A. Lounine, T. Okugi, N. Toge
KEK, Ibaraki
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Designs for a future TeV scale electron-positron X-band linear collider (NLC/GLC) require main linac units which produce and deliver 450 MW of rf power at 11.424 GHz to eight 60 cm accelerator structures. The design of this rf unit includes a SLED-II pulse compression system with a gain of approximately three at a compression ratio of four, followed by an overmoded transmission and distribution system. We have designed, constructed, and operated such a system as part of the 8-Pack project at SLAC. Four 50 MW X-band klystrons, running off a common 400 kV solid-state modulator, drive a dual-moded SLED-II pulse compression system. The compressed power is delivered to structures in the NLCTA beamline. Four 60 cm accelerator structures are currently installed and powered, with four additional structures and associated high power components available for installation late in 2004. We describe the layout of our system and the various high-power components which comprise it. We also present preliminary data on the processing and initial high-power operation of this system.
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Video of talk
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Transparencies
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| MOPLT139 |
Beam-based Alignment and Beta Function Measurements in PEP-II
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866 |
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- G. Yocky, J. Nelson, M.C. Ross, T.J. Smith, J.L. Turner, M. Woodley
SLAC, Menlo Park, California
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Careful optics studies and stringent lattice control have been identified as two key components to increasing PEP-II luminosity. An accurate, trusted BPM system is required for both of these strategies. To validate the existing BPM system and to better understand some optical anomalies in the PEP-II rings, an aggressive program of beam-based alignment (BBA) has been initiated. Using a quad-shunt BBA procedure in which a quadrupole?s field strength is varied over a range of beam positions, relative offsets are determined by the BPM readings at which quadrupole field changes no longer induce a closed orbit shift. This procedure was verified in the HER and is well underway in the LER IR. We have found many surprisingly large BPM offsets, some over one centimeter, as well as a number of locations where the current nominal orbit is several millimeters from the quadrupole center. Tune versus quadrupole field data were taken during the BBA process in the LER IR, and the non-linear response in each case is compared to simulation to infer local beta functions.
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| MOPLT107 |
Nanosecond-timescale Intra-bunch-train Feedback for the Linear Collider: Results of the FONT2 Run
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785 |
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- P. Burrows, T. Hartin, S.M. Hussain, S. Molloy, G.R. White
Queen Mary University of London, London
- C. Adolphsen, J.C. Frisch, L. Hendrickson, R.K. Jobe, T. Markiewicz, D.J. McCormick, J. Nelson, M.C. Ross, S. Smith, T.J. Smith
SLAC, Menlo Park, California
- R. Barlow, M. Dufau, A. Kalinin
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- G. Myatt, C. Perry
OXFORDphysics, Oxford, Oxon
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We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalisation scheme to account for beam current variations along the train. We used the system to correct the position of the 170 nanosecond-long bunchtrain at NLCTA, in both 'feed forward' and 'feedback' modes. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider.
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| MOPLT142 |
Analysis of KEK-ATF Optics and Coupling Using LOCO
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872 |
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- M. Woodley, J. Nelson, M.C. Ross
SLAC/NLC, Menlo Park, California
- A. Wolski
LBNL/AFR, Berkeley, California
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LOCO is a computer code for analysis of the linear optics in a storage ring based on the closed orbit response to steering magnets. The analysis provides information on focusing errors, BPM gain and rotation errors, and local coupling. Here, we discuss the details of the LOCO implementation at the KEK-ATF Damping Ring, and report the initial results. Some of the information obtained, for example on the BPM gain and coupling errors, has not previously been determined. We discuss the possibility of using the data provided by the LOCO analysis to reduce the vertical emittance of the ATF beam.
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