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Multi-Stage Bunch Compressors for the International LinearCollider

Description: We present bunch compressor designs for theInternationalLinear Collider (ILC) which achieve a reduction in RMS bunch length from6 mm to 0.3 mm via multiple stages of compression, with stages ofacceleration inserted between the stages of compression. The keyadvantage of multi-stage compression is that the maximum RMS energyspread is reduced to approximately 1 percent, compared to over 3 percentfor a single-stage design. Analytic and simulation studies of themulti-stage bunch compressors are presented, along with performancecomparisons to a single-stage system. Parameters for extending thesystems to a larger total compression factor are discussed.
Date: May 16, 2005
Creator: Tenenbaum, Peter G.; Raubenheimer, Tor O. & Wolski, Andrzej
Partner: UNT Libraries Government Documents Department

Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

Description: Computer simulations using the 2D code"POSINST" were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was less than approximately 0.6 T, equilibrium average electron densities were up to three times the density found at other neighboring field values. Effects of this resonance between the bunch and cyclotron frequency are expected to be non-negligible when the beam bunch length is much less than the product of the electron cyclotron period and the beam velocity, for a beam moving at v~;;c. Details of the dynamics of the resonance are described.
Date: September 2, 2008
Creator: Celata, C. M.; Furman, Miguel A.; Vay, J.-L. & Yu, Jennifer W.
Partner: UNT Libraries Government Documents Department

Analysis of KEK-ATF Optics and Coupling Using LOCO

Description: LOCO is a code for analysis of the linear optics in astorage ring based on the closed orbit response to steering magnets. Theanalysis provides information on focusing errors, BPM gain and rotationerrors,and local coupling. Here, we report the results of an applicationof LOCO to the KEK-ATF. Although the analysis appears to have provideduseful information on the optics of the machine, it appears that one ofthe main aims of the study to reduce the vertical emittance by correctingthe local coupling was not successful, and we discuss some possiblereasons for this.
Date: January 12, 2004
Creator: Wolski, Andrzej; Ross, Marc; Woodley, Mark; Nelson, Janice & Mishra, Shekhar
Partner: UNT Libraries Government Documents Department

Configuration Studies and Recommendations for the ILC DampingRings

Description: We describe the results of studies comparing differentoptions for the baseline configuration of the ILC damping rings. Theprincipal configuration decisions apply to the circumference, beamenergy, lattice type, and technology options for key components,including the injection/extraction kickers and the damping wigglers. Toarrive at our recommended configuration, we performed detailed studies ofa range of lattices representing a variety of different configurationoptions; these lattices are described in Chapter 2. The results of thevarious studies are reported in chapters covering issues of beamdynamics, technical subsystems, costs, and commissioning, reliability andupgradeability. Our detailed recommendations for the baselineconfiguration are given in Chapter 7, where we also outline furtherresearch and development that is needed before a machine using ourrecommended configuration can be built and operated successfully. In thesame chapter, we suggest possible alternatives to the baselineconfiguration.
Date: February 4, 2006
Creator: Wolski, Andrzej; Gao, Jie & Guiducci, Susanna
Partner: UNT Libraries Government Documents Department

Configuration Studies and Recommendations for the ILC DampingRings

Description: We describe the results of studies comparing differentoptions for the baseline configuration of the ILC damping rings. Theprincipal configuration decisions apply to the circumference, beamenergy, lattice type, and technology options for key components,including the injection/extraction kickers and the damping wigglers. Toarrive at our recommended configuration, we performed detailed studies ofa range of lattices representing a variety of different configurationoptions; these lattices are described in Chapter 2. The results of thevarious studies are reported in chapters covering issues of beamdynamics, technical subsystems, costs, and commissioning, reliability andupgradeability. Our detailed recommendations for the baselineconfiguration are given in Chapter 7, where we also outline furtherresearch and development that is needed before a machine using ourrecommended configuration can be built and operated successfully. In thesame chapter, we suggest possible alternatives to the baselineconfiguration.
Date: February 4, 2006
Creator: Wolski, Andrzej; Gao, Jie & Guiducci, Susanna
Partner: UNT Libraries Government Documents Department

A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

Description: Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.
Date: June 11, 2008
Creator: Pivi, M. T.; Pivi, M.T.F.; Ng, J.S.T.; Arnett, D.; Cooper, F.; Kharakh, D. et al.
Partner: UNT Libraries Government Documents Department