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| MOPLT108 | TESLA Linac-IP Simulations | luminosity, feedback, simulation, linac | 788 | ||
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We have formulated integrated simulations of the transport of the electron and positron bunches in the Linear Collider from the linac entrance through the beam delivery system and the interaction region, taking wakefield effects into account. We have set up the simulations to run on the 64-cpu prototpye Grid cluster at QMUL and generated results for various sets of input parameters for the TESLA and NLC machines. For TESLA we have evaluated the distortion of the phase-space of the bunches at the interaction point due to wakefields. We have calculated the luminosity degradation and the production of photons and e+e- pairs. We have simulated the performance of the intra-train beam feedback systems based on bunch position, angle and luminosity measures, and have evauated the luminosity recovery potential of these systems for TESLA and NLC.
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| MOPLT138 | Vibrational Stability of GLC/NLC Linear Collider: Status and R&D Plans | site, simulation, luminosity, collider | 863 | ||
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Luminosity stability of the X-band linear collider will be provided by beam-based train by train steering feedbacks in the linac and at the IP, optional active stabilization of the final doublet, being developed to counteract possible excessive vibration of the detector, and optional fast intratrain feedback that would allow delivering major part of the luminosity while other systems are being commissioned. Control and reduction of the beam jitter originating from vibration of collider components is part of our strategy described in this paper.
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| TUPLT038 | Closed Orbit Correction and Orbit Stabilisation Scheme for the 6 GEV Synchrotron Light Source PETRA III | emittance, closed-orbit, quadrupole, insertion | 1231 | ||
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PETRA III is a 6 GeV synchrotron light source being reconstructed out of the existing storage ring PETRA II. It will have a horizontal beam emittance of 1nm.rad and a 1% emittance ratio. Since the vertical beam sizes are ~5?10 micron in the low gap undulators sections the beam position stability requirement in the vertical plane is between 0.5 and 1 micron whereas the stability requirement in the horizontal plane is more relaxed. In this paper determination of golden orbit in the presence of magnetic field errors and magnet misalignments and correction of vertical spurious dispersion is discussed. A scheme of slow and fast orbit correction using the SVD algorithm has been developed. The distribution of monitors and the location of slow and fast correctors are reported. Estimations of the parameters of the fast orbit feedback have been derived from present measurements on PETRA II.
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| WEPKF037 | Structural Analysis of an Integrated Model of Short Straight Section, Service Module, Jumper Connection and Magnet Interconnects for the Large Hadron Collider | alignment, vacuum, collider, hadron | 1684 | ||
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The Short Straight Section (SSS) of the Large Hadron Collider (LHC) houses a twin quadrupole.The cryogens are fed to the SSS through a Jumper Connection between service modules of Cryogenic Distribution Line (QRL) and SSS.A Finite Element analysis has been performed in collaboration with CERN for the unified model of SSS of LHC,consisting of cold mass, cold supports,vacuum vessel and its bellows, interconnects, jumper connection and alignment jacks. The model has been developed to understand coupling between the quadrupole magnet and the service module due to ground motion and during the realignment or global smoothening of the LHC arc. The model incorporates experimental stiffness values for support posts, internal pipes and jacks and calculated stiffness for magnet-to-magnet interconnects. The computation space and time has been reduced by executing a two step linear static analycal approach with an initial trial analytical approach cycle in which the program estimates the behavior of the flexibles. A special routine is developed within ANSYS,using APDL which selects the correct secant stiffness of flexibles(by applying a user interactive logical algorithm)from their non-linear force displacement characteristics.
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| WEPKF048 | Characteristics of Ground Motion at KEK and SPring-8 | site, power-supply, linear-collider, collider | 1711 | ||
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Authors Y. Nakayama, T. Ito, (JPOWER); R. Sugahara, S. Takeda, H.Yamaoka, M.Yoshioka (KEK); S.Matsui, C.Zhang (SPring-8); S. Yamashita (ICEPP): Abstract Stability of ground is preferable for accelerator beam operation. We have measured ground motion of ground at the KEKB and SPring-8 site, where the ground has quite different characteristics each other. In this paper, some of analysis results are shown, and the characteristics of the ground motion at the KEKB site and those at the Spring-8 site are compared.
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| WEPLT113 | Development of New Hydrostatic Levelling Equipment for Large Next Generation Accelerator | site, alignment, klystron, target | 2113 | ||
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The Hydrostatic Levelling Systems (HLS) are installed and commissioned in many laboratories. We have developed a new type hydrostatic levelling equipment for the large future accelerator. The designing points are as followings: (1) use of half filled water level sensor instead of the usual full filled level sensor, (2) the capacitive sensor is supported by an invar rod and (3) use of digitized signal transfer system. These three points are very important factor to apply the leveling system to large next generation accelerator in order to obtain good temperature stability and being free from the environmental electronic noises. We have obtained a typical resolution of the equipment as 0.3 micron-meter, though usual HLS shows the value ten times as much. We are going to show a detailed report about the system including data obtained.
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| THPKF011 | Vibration Measurements at the Swiss Light Source (SLS) | quadrupole, site, resonance, lattice | 2278 | ||
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Vibration measurements have been carried out at the Swiss Light Source (SLS) site as part of a collaboration between the Paul Scherrer Institute (PSI) and the European Organization for Nuclear Research (CERN). The vibration level of the SLS floor and of some lattice elements of the SLS ring have been monitored under various experimental conditions. In particular, vibration spectra of lattice quadrupoles have been measured with a circulating beam and compared with the spectra of transverse beam positions, as measured with beam position monitors. This paper summarizes the results.
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| THPLT156 | Simulations of IP Feedback and Stabilization in the NLC | feedback, luminosity, simulation, site | 2825 | ||
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Keeping nanometer-sized beams in collision is an essential component in achieving design luminosity in a linear collider. The NLC stabilization strategy is conservative by including enough redundancy so that if some piece doesn't work to specification or the incoming beam motion is worse than expected, the beams will still be kept in collision. We show simulation results with both realistic and pessimistic assumptions about the response of the ground motion, inertial stabilization, interbunch and intertrain feedback systems. By providing backup systems, and by assuming that some systems may perform more poorly than expected, we can achieve a high level of confidence in our ability to successfully stabilize the beams.
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| THPLT157 | Beam-based Feedback for the NLC Linac | feedback, linac, emittance, simulation | 2828 | ||
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The NLC linac train-by-train feedback system is designed to stabilize the beam trajectory, but is also a valuable element in the strategy for emittance preservation. New simulations employ improved strategies [*], allowing beam steering to be performed significantly less often than without the feedback system. Additional simulations indicate that the linac feedback can contribute towards successful operation at noisier sites.
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* Beam-based Feedback Simulations for the NLC Linac, L. Hendrickson et al., LINAC, Monterey, California (2000) |
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