| Paper | Title | Page |
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| WEPP016 | FEL-based Coherent Electron Cooling for High-energy Hadron Colliders | 2560 |
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Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation of such beams is too feeble and two common methods, stochastic and electron cooling, are not efficient in providing significant cooling for high energy hadron, especially proton, colliders. In this paper we discuss a practical scheme of Coherent Electron Cooling, which promises short cooling times (below one hour) for intense proton beams in RHIC at 250 GeV or in LHC at 7 TeV*. Coherent Electron Cooling was suggested early 1980s as a possibility for using various microwave instabilities in an electron beam to enhance its interaction with hadrons**. The capabilities of present-day accelerator technology, ERLs, and high-gain Free-Electron Lasers (FELs), finally caught up with the idea and provided the all necessary ingredients for realizing such a process at energies typical for modern high energy hadron colliders. In this paper, we discuss the principles, the main limitations of this scheme and present some predictions for Coherent Electron Cooling in RHIC and the LHC operating with ions or protons.
*V. N. Litvinenko, Y. S. Derbenev, Proc. 29th Int. FEL Conference, Novosibirsk, August, 2007. |
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| WEPP049 | Advances on ELIC Design Studies | 2632 |
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| An electron-ion collider of a center-of-mass energy up to 90 GeV at luminosity up to 1035 cm-2s-1 with both beams highly polarized is essential for exploring the new QCD frontier of strong color fields in nuclear and precisely imaging the sea-quarks and gluons in the nucleon. A conceptual design of a ring-ring collider based on CEBAF (ELIC) with energies up to 9 GeV for electrons/positrons and up to 225 GeV for protons and 100 GeV/u for ions has been proposed to fulfill the science desire and to serve as the next step for CEBAF after the planned 12 GeV energy upgrade of the fixed target program. Here, we summarize recent design progress for the ELIC complex with four interaction points (IP); including interaction region optics with chromatic aberration compensation scheme and complete lattices for the Figure-8 collider rings. Further optimization of crab crossing angles at the IPs, simulations of beam-beam interactions and electron polarization in the Figure-8 ring and its matching at the IPs are also discussed. | ||
| WEPP123 | Isochronous Pion Decay Channel for Enhanced Muon Capture | 2785 |
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| Intense muon beams have many potential applications, including neutrino factories and muon colliders. However, muons are produced in tertiary beams into a diffuse phase space. To make useful beams, the muons must be rapidly cooled before they decay. A promising new concept for the collection and cooling of muon beams is being investigated, namely, the use of a nearly Isochronous Helical Transport Channel (IHTC) to facilitate capture of muons into RF bunches. Such a distribution could be cooled quickly and coalesced into a single bunch to optimize the luminosity of a muon collider. We describe the IHTC and provide simulations demonstrating isochronicity, even in the absence of RF and absorber. | ||
| WEPP147 | Aberration-free Muon Transport Line for Extreme Ionization Cooling: a Study of Epicyclic Helical Channel | 2833 |
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| Once the normalized transverse emittances of a muon beam have been cooled to some hundreds of microns, new techniques such as Parametric-resonance Ionization Cooling and Reverse Emittance Exchange can be used to focus the beam very tightly on beryllium energy absorbers for further transverse emittance reduction. The transport lines for these techniques have stringent requirements for the betatron tunes so that resonance conditions are properly controlled and for the dispersion function so that the longitudinal emittance can be controlled by emittance exchange using wedge-shaped absorbers. The extreme angular divergence of the beam at the absorbers implies large beam extension between the absorbers such that these techniques are very sensitive to chromatic and spherical aberrations. In this work we describe general and specific solutions to the problem of compensating these aberrations for these new muon cooling channels. | ||
| WEPP149 | Advances in Parametric-resonance Ionization Cooling | 2838 |
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| Parametric-resonance ionization cooling (PIC) is a muon-cooling technique that is useful for low-emittance muon colliders. This method requires a well-tuned focusing channel that is free of chromatic and spherical aberrations. The dispersion function of the channel must be large where the correction magnets are placed for aberration control but small and non-zero where the ionization cooling beryllium wedges are located to provide emittance exchange to maintain small momentum spread. In order to be of practical use in a muon collider, it also necessary that the focusing channel be as short as possible to minimize muon loss due to decay. A compact PIC focusing channel is described in which new magnet concepts are used to generate the required lattice functions. | ||
| THPC085 | VORPAL Simulations Relevant to Coherent Electron Cooling | 3185 |
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Coherent electron cooling (CEC)* combines the best features of electron cooling and stochastic cooling, via free-electron laser technology**, to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the “modulator” and “kicker” regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations*** of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results. In particular, we compare the semi-analytic binary collision model with electrostatic particle-in-cell (PIC).
*Ya. S. Derbenev, COOL ’07 Proc. (2007). |