| Paper | Title | Page |
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| MO6RFP064 | Stacking Simulations for Compton Positron Sources of Future Linear Colliders | 512 |
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The Compton positron source of a future linear collider must obtain the target bunch population by accumulating a large number of positron packets, arriving either in a number of bursts from a “Compton ring”, with intermediate damping of the scattering electron beam, or quasi-continually from a “Compton energy recovery linac”. We present simulation results for the longitudinal stacking of Compton positrons in the ILC damping ring and the CLIC pre-damping ring, reporting parameter optimization, stacking efficiency, possible further improvements, and outstanding questions. |
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| WE5RFP086 | New Materials and Designs for Superconductive Insertion Devices | 2471 |
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NbTi wires are relatively easy to handle and are therefore up to now the preferred material for superconductive insertion devices. Yet other materials, like Nb3Sn, MgB2 or high temperature superconductors, are less sensitive to beam heat load and/or are able to produce higher magnetic fields. In this paper the different superconducting materials and their advantages and challenges are discussed. Additionally this paper describes new designs for special insertion devices like damping wigglers and undulators for laser wakefield accelerators. |
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| WE6PFP105 | Lattice Options for the CLIC Damping Rings | 2757 |
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Optics design optimisation studies have been undertaken for the CLIC damping ring lattice. Main parameters such as the ring energy and output longitudinal emittance were reconsidered in order to reduce the detrimental effect of collective instabilities. In this respect, the low emittance arc cell length was rationalized taking into account space and magnet design requirements. The straight section cell filled with super-conducting wigglers was modified to accommodate a robust absorption scheme. Several low emittance rings were considered and compared with respect to their dynamic aperture and the IBS-dominated output emittances. |
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| WE6PFP107 | Design Considerations for the CLIC Pre-Damping Rings | 2760 |
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The CLIC pre-damping rings have to accommodate a large emittance beam, coming in particular from the positron target and reduce its size to low enough values for injection into the main damping rings. In particular, polarized positron stacking imposes stringent requirements with respect to longitudinal acceptance and damping times. Linear lattice design options based on low-emittance cells, multiple bend cells and the inclusion of damping wigglers are compared with respect to linear optics functions, tunability, chromatic properties and acceptance. The optics of special regions for the placement of injection, extraction and RF elements are also presented. Non-linear dynamics simulations are finally undertaken for evaluating and maximizing the rings dynamic aperture, especially for large momentum spreads. |
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| WE6RFP017 | Collimation Considerations for PS2 | 2817 |
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A main concern in high intensity rings is the evaluation of uncontrolled losses and their minimization using collimation systems. A two-stage systemis foreseen for the PS2. The fundamental design strategy for the collimation design is presented, including machine apertures and collimator materials. The dependence of the collimator system efficiency on the primary scraper length and the impact parameter of the particle is evaluated for different collimator locations. Beam loss maps are finally produced displaying the detailed power load deposited around the ring. |
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| WE6RFP065 | The CLIC Positron Source Based on Compton Schemes | 2945 |
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The CLIC polarized positron source is based on a positron production scheme in which polarized photons are produced by Compton process. Compton backscattering happens in a so-called "Compton ring" where an electron beam of 1.06 GeV interacts with a powerful laser beam amplified in an optical resonator. The circularly-polarized gamma rays are sent on to a target, producing pairs of longitudinally polarized electrons and positrons. An Adiabatic Matching Device maximizes the capture of the positrons. A normal-conducting 2 GHz Linac accelerates the beam up to 2.424 GeV before injection into the Pre-Damping Ring (PDR). The nominal CLIC bunch population is 4.4x109 particles per bunch. Since the photon flux coming out from a "Compton ring" is not sufficient to obtain the requested charge, a stacking process is required in the PDR. Another option is to use a "Compton Energy Recovery Linac" where a quasi-continual stacking in the PDR could be achieved. A third option is to use a "Compton Linac" which would not require stacking. We describe the overall scheme as well as advantages and constraints of the three different options. |
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| TH6PFP039 | Beam Loss Control for the Unstripped Ions from the PS2 Charge Exchange Injection | 3790 |
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Control of beam losses is an important aspect of the H- injection system for the PS2, a proposed replacement of the CPS in the CERN injector complex. H- ions may pass the foil unstripped or be partially stripped to excited H0 states which may be stripped in the subsequent strong-field chicane magnet. Depending on the choice of the magnetic field, atoms in the ground and first excited states can be extracted and dumped. The conceptual design of the waste beam handling is presented, including local collimation and the dump line, both of which must take into account the divergence of the beam from stripping in fringe fields. Beam load estimates and activation related requirements of the local collimators and dump are briefly discussed. |
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| TH6PFP043 | Orbit, Optics and Chromaticity Correction for PS2 Negative Momentum Compaction Lattices | 3802 |
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The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattices of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the different lattices is finally evaluated. |
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| TH6PFP044 | Linear Optics Design of Negative Momentum Compaction Lattices for PS2 | 3805 |
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In view of the CERN Proton Synchrotron proposed replacement with a new ring (PS2), a detailed optics design as been undertaken following the evaluation of several lattice options. The basic arc module consists of cells providing negative momentum compaction. The straight section is formed with a combination of FODO and quadrupole triplet cells, to accommodate the injection and extraction systems, in particular the H- injection elements. The arc is matched to the straight section with a dispersion suppressor and matching module. Different lattices are compared with respect to their linear optics functions, tuning flexibility and geometrical acceptance properties. |
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| FR5RFP004 | Generation of Short Proton Bunches in the CERN Accelerator Complex | 4542 |
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Short high-energy proton bunches have been proposed as efficient drivers for future single-stage electron-beam plasma accelerators. We discuss if and how the desired proton bunches could be obtained in the CERN accelerator complex, considering various compression schemes, such as a fast non-adiabatic lattice change prior to extraction from a storage ring or the use of transversely deflecting cavities. |