| Paper | Title | Page |
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| MOPC114 | Status of the Electrostatic and Cryogenic Double Ring DESIREE | 331 |
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| DESIREE is a double electrostatic storage ring being built at the Manne Siegbahn Laboratory and Stockholm University. The two rings in DESIREE have the same circumference, 8.7m, and a common straight section along which stored ions can interact. The ion optics for both rings will be housed in a single double walled vacuum chamber built like a cryostat with a radiation screen and several layers of super insulation in between the two chambers. The inner chamber, which holds all the optical elements, will be cooled by four cryogenerators attached to the bottom of this chamber. It is constructed in pure aluminum to ensure good thermal conductivity over the whole structure. The whole accelerator structure will be cooled below 20K. This low temperature in combination with the unique double ring structure will result in a powerful machine for studying interactions between cold molecular ions close to zero relative energy. The outer vacuum chamber is constructed in steel with a high magnetic permeability to provide an efficient screening of the earth magnetic field. DESIREE will be provided with two injectors which will be able to supply both positive and negative ions to both rings. | ||
| TUPC116 | Field Characterization of XFEL Quadrupole Magnets | 1338 |
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The European X-ray free electron laser (XFEL) will be one of the most advanced light source facilities in Europe and produce high intensity laser light of wavelengths down to 0.1 nm*. The laser light is produced and amplified by electrons moving through long undulator systems, each consisting of several 5 m long segments. After each undulator segment an adjustable quadrupole magnet is placed to focus the electron beam. For optimum control of the laser light the centre of the quadrupoles need to be positioned along a straight line with an accuracy of 0.001 mm which only can be reached by beam based alignment (BBA). Prior to the BBA procedure the magnets need to be aligned along the beam path, therefore the centre position of the magnet has to be determined relative to fiducials placed on the magnet body with an accuracy of approximately 0.01 mm. A rotating coil system has been set up at the Manne Siegbahn Laboratory to characterize the magnetic field between the four magnetic poles and to measure the stability of the magnetic centre. The accuracy of this instrument and procedures of how to fiducialize the magnetic centre are presented.
*European XFEL technical design report, edited by M. Altarelli et. al., DESY 2006. |
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| THPP046 | Applicability of Stochastic Cooling in Small Electrostatic Storage Rings | 3464 |
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Several small electrostatic storage rings have been built or are being built for experiments in atomic and molecular physics. One example is the DESIREE double electrostatic storage ring* under construction at the Manne Siegbahn Laboratory. At the KEK electrostatic storage ring, electron cooling of 20 keV protons has been demostrated**. For heavy molecules, however, including bio-molecules, electron-cooling times are unrealistically long because of the low ion velocity and the correspondingly low electron energy which results in very small electron currents. For this reason, electron cooling is not foreseen for DESIREE. The rates of stochastic cooling, on the other hand, are at first glance unrelated to beam energy. Furthermore, the low particle numbers expected for many heavy molecules seem to make stochastic cooling attractive, theoretical rates being inversely proportional to particle numbers. In this paper, the rates of stochastic cooling for slow heavy particles are investigated with respect to, mainly, the bandwidths and signal strengths that can be expected at the low particle velocieties that are of interest at, e.g., DESIREE, and some numerical examples are presented.
* P. Löfgren et al., these proceedings |
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| THPP049 | Status of Electron Cooler Design for HESR | 3473 |
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| The HESR-ring of the future FAIR-facility at GSI will include both electron cooling and stochastic cooling in order to achieve the demanding beam parameters required by the PANDA experiment. The high-energy electron cooler will cool antiprotons in the energy range 0.8 GeV to 8 GeV. The design is based on an electrostatic accelerator and shall not exclude a further upgrade to the full energy of HESR, 14.1 GeV. The paper will discuss prototype tests of critical components and recent development in the design including the high-voltage tank, electron gun and collector, magnet system, electron beam diagnostics and the magnetic field measuring system. | ||
| THPP052 | Electron Cooling Force Calculations for HESR | 3482 |
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| The High energy storage ring HESR at FAIR is being realized by a consortium consisting of Forschungszentrum Jülich, GSI Darmstadt and Uppsala University. An important feature of this new facility is the combination of phase-space cooled beams and dense internal targets. Charmonium spectroscopy, which is one of the main items in the experimental program, requires antiproton momentum up to 8.9 GeV/c with a resolution of dp/p=0.00001. This can only be achived with electron cooling. The electron cooler proposed for HESR allows beam cooling between 1.5 GeV/c and 8.9 GeV/c. Along the 24 m interaction section beween electrons and antiprotons, the electrons are guided by a solenoid field of 0.2 T with a field straightness of 0.00001 radians rms. To predict the final momentum resolution of the antiproton beam in HESR, electron cooling force calculations, simulations of electron cooling and comparison to experimental data are needed. This paper focuses on the force calculations. The method is based on the theory by Derbenev and Skrinsky, (i.e. the Vlasov techique) and the electron cooling force is numerically calulated using adaptive Monte Carlo integration methods. |