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[en] Electron cooling has numerous areas of application, though some issues of the behavior of an ion beam under the action of electron cooling are still unclear. This report covers a portion of these issues in expectation that knowledge about the cooling dynamics of an intense ion beam will open up new possibilities for the application of electron cooling.
[en] A low-energy test set-up for the measurement and optimisation of secondary electron currents from the collector in electron coolers is presented. A variable-field Wien filter and current-measuring aperture plates grant insight into the trajectory and energy distribution of the secondary particles. While secondary electrons flowing back from the collector can be bent away and dumped, these electrons in turn create new secondaries (“tertiaries”), and the resulting cascade is what ultimately limits the performance of the whole collector assembly, i.e. collector, optics, and Wien filter as a complete unit. Our set-up aims at understanding the behaviour of secondary and tertiary electrons inside this assembly. Using the included diagnostic devices, the efficiency of the collector itself can be measured as a function of the beam parameters and optics; some measurements of a COSY-style collector are given as an example.
[en] COSY Juelich is a cooler synchrotron and storage ring with a proton momentum range from 270 to 3300 MeV/c. It has been conceived to deliver high precision beams for medium energy physics. To accomplish this goal two cooling systems are used. An electron-cooling system that reaches up to a momentum of 645 MeV/c and a stochastic cooling system that covers the upper momentum range from 1500 to 3300 MeV/c. Since its inauguration in April 1993 substantial progress in developing beams for the experiments has been achieved and the physics program has started with first measurements. Proton beams in a wide energy range have been delivered to internal as well external experiments. Important design features of the machine and results of the commissioning process are presented. (orig.)
[en] Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o'clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.
[en] The first electron cooling system for LEAR will cover the momentum range between 100 and 600 MeV/c. Recently, the assembly of a new vacuum system with modified electron gun and collector from the Initial Cooling Experiment (ICE) has been finished. In the present configuration, gun and collector allow for cooling antiprotons at momenta up to 370 MeV/c. A new gun and collector for the higher momenta are being designed. After separate tests in 1985, the cooler will be ready for installation at the end of this year. In this report, we will describe the cooling device and its performance expected after the installation
[en] The longitudinal stability of intense, low momentum spread ion beams is of great interest today, especially in electron-cooled storage rings. Stability conditions are usually formulated as the limitations on the allowed value of beam-chamber coupling impedances. In the case of cooled beams, the effect of cooling can not be neglected if the cooling rate is comparable with the revolution frequency spread. The effect of the electron cooling can be described by the Fokker-Planck equation. In this paper the author presents a simple analytical method to derive dispersion relations for the longitudinal coasting beam instabilities using a perturbative approach. Numerical examples applied to 45 MeV protons in the IUCF cooling ring are presented
[en] The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt is planned as an antiproton storage ring in the momentum range from 1.5 to 15 GeV/c. The HESR is being designed and built by a consortium consisting of IKP at Forschungszentrum Juelich, TSL at Uppsala University, and GSI Darmstadt. An important feature of this new facility is the combination of phase-space cooled beams and thick internal targets (e.g. pellet targets) which results in demanding beam parameter requirements for two operation modes: high luminosity mode with peak luminosities of up to 2 · 1032cm-2s-1 and high resolution mode with a relative momentum spread in the order of a few times 10-5. To reach these beam parameters one needs a very powerful phase-space cooling utilizing high-energy electron cooling and high-bandwidth stochastic cooling. In this paper different beam dynamics issues like closed orbit correction, performance of cooled beams interacting with internal targets and luminosity considerations are discussed. (author)
[en] Within the past decade, a number of laboratories have embarked upon construction projects having in common the application of synchrotron and/or storage ring technology to research in atomic and nuclear physics. The designs span a wide range of ion species and energies. Most of these projects plan to employ stochastic cooling and/or electron beam cooling techniques. The sudden burgeoning of interest in the application of technology originating in the high energy accelerator community has clearly been influenced by the success of cooling in test rings and in the LEAR project. Why have they so many new projects of this type? Are they likely to perform well enough to justify the current level of effort and the significant allocation of resources to the construction of these facilities? What can they say about the performance boundaries of these devices before they are in operation. The paper attempts to summarize the authors present understanding of the likely behavior of these devices and reviews pertinent design features. Some examples of the experimental applications which appear well-suited to the properties of these rings are described
[en] The paper treats the possibility of using electron cooling to accumulate low-energy cold positrons and using them to produce antihydrogen. A model version of a storage facility with an intensity of a few thousand anti-atoms per second is considered. Ways for its further modification are discussed. (author) 12 refs., 2 figs
[en] Synchrotron motion with an external rf voltage modulation was studied experimentally. Beam particles, in the presence of electron cooling, were observed to damp to the basins of resonance islands, which were produced by the parametric resonance of the rf voltage modulation. The measured phase amplitudes of the centers of these resonance islands were found to agree well with theory