| Paper | Title | Page |
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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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| THPP047 | Prototype of the High Voltage Section for the 2 MeV Electron Cooler at COSY | 3467 |
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| The design, construction and installation of a 2 MeV electron cooling system for COSY-Juelich is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at FAIR/GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The design and first experiments of a new developed prototype of the high voltage section, consisting of a gas turbine, magnetic coils and high voltage generator with electronics is reported. | ||
| THPP048 | Experimental Demonstration of Longitudinal Ion Beam Accumulation with Electron Cooling | 3470 |
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Recently, two longitudinal beam compression schemes have been successfully tested in the Experimental Storage Ring (ESR) at GSI with a beam of bare Ar ions at 65 MeV/u injected from the ion synchrotron SIS18. The first employs Barrier Bucket pulses, the second makes use of multiple injections around the unstable fixed point of a sinusoidal RF bucket at h=1. In both cases continuous electron cooling maintains the stack and merges it with the freshly injected bunch *. Using the beam diagnostic devices in the ring both stacking processes were demonstrated under the same conditions. The dependence of the accumulation performance on the available rf potential, the electron cooling strength as well as on the synchronization conditions between injection kicker pulse and rf wave was investigated. These experimental results provide the proof of principle for the planned fast stacking of Rare Isotope Beams aiming at high luminosities in the New Experimental Storage Ring ** of the FAIR project ***.
* C. Dimopoulou et al., JACoW Proceedings of COOL07, Bad Kreuznach,2007. |
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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. | ||
| THPP050 | Recent Status of Laser Cooling for Mg Realized at S-LSR | 3476 |
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At an ion storage and cooler ring, S-LSR, a laser cooling has been applied to the 40 keV 24Mg+ ion beam guiding a laser with the wave length of 280nm parallel to the ion beam together with the deceleration by an induction voltage. Up to now, the longitudinal temperature has been cooled down to 3.6 Kelvin for the ion number of 3x104 although the transverse one still remains around 500 Kelvin. The longitudinal temperature is limited by the heat transfer from the transverse degree of freedom through intra-beam scattering, which becomes stronger according to increase of ion number. It is found that the equilibrium longitudinal temperature is linearly coupled with the transverse one* for our experimental condition up to now. In the present paper, recent experimental data will be presented together with the procedure of beam diagnosis with the use of optical methods using a spontaneous emission of the Mg ions. Possible approach to realize the resonant coupling through synchro-betatron coupling** is also to be presented.
* M. Tanabe et al., To be published in Applied Physics Express (APEX). |
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| THPP051 | Stochastic Cooling in the Framework of the FAIR Project at GSI | 3479 |
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| Stochastic cooling at FAIR will be one of the instruments to get cooled beams of rare isotopes and antiprotons for high resolution experiments. Stochastic cooling systems will be installed in the CR and RESR storage rings. The Collector Ring CR is a dedicated storage ring for the first step cooling of antiproton beams (3 GeV or β=0.97) produced at the antiproton production target, and of radioactive beams (740 MeV/u or β=0.83) prepared in the Super Fragment Separator. The pick-up and kicker systems have designs which allow very efficient cooling for both particle velocities. There will be different ring optical settings for optimum cooling of antiprotons or rare isotopes. Whereas the next cooling step for rare isotopes will be electron cooling, antiprotons will be accumulated in the RESR using a similar accumulation scheme which was formerly applied at the AA at CERN. The paper presents the CR and RESR system layouts and new hardware developments. | ||
| 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. | ||
| THPP053 | One-dimensional Ordering of Protons by the Electron Cooling | 3485 |
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| One of the main subjects of the compact cooler ring, S-LSR at Kyoto University is the physics of the ultra cold ion beam, such as the ordered beam and the crystalline beam, using the electron and laser cooling. The one-dimensional ordering of protons has been studied at S-LSR, while the ordering the highly charged heavy ions has been found at ESR and CRYRING. Abrupt jumps in the momentum spread and the Schottky noise power have been observed for protons at a particle number of around 2000. The beam temperature was 0.17 meV and 1 meV in the longitudinal and transverse directions at the transition, respectively. The normalized transition temperature of protons is close to those of heavy ions at ESR. The lowest longitudinal beam temperature below the transition was 0.3 K. It is close to the longitudinal electron temperature. The dependence of the ordering conditions on the betatron tune and the transverse beam temperature have been also studied. These results will be presented in the presentation. | ||
| THPP054 | Laser Cooling of Bunched Ion Beam at S-LSR | 3488 |
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S-LSR is an ion storage ring equipped with an electron cooler and a laser cooling system. The laser cooling experiments of coasting beams were carried out during last year*. Now we started bunched beam laser cooling. 40keV Mg+ beams are bunched by an untuned RF cavity for harmonic number 5-50, and is cooled by a single 280nm laser. Bunch length are measured by electrostatic pickups. When RF harmonic number is five, bunch lengths is shorten from 1m to under 0.14m by laser cooling. Since the bunch length after cooling is shorter than present monitor resolution, fluorescence measurement is in preparation. We have installed another small RF cavity for harmonic number 100. Synchrotron-betatron coupling will be induced by dispersion at the place of this cavity**. This effect is expected to realize three dimensional laser cooling. In this paper we present the result of bunched beam cooling and the trial to three dimensional laser cooling.
*M. Tanabe et al. Appl. Phys. Express, in press. |
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| THPP055 | Stochastic Cooling Developments for the HESR at FAIR | 3491 |
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| The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability in the newly designed normal conducting ring lattice of the HESR. Theoretical predictions have been compared to experimental cooling results with internal targets at the COSY facility. Recent developments for the HESR stochastic cooling equipment will be discussed. The design of new high sensitive printed loop couplers and ring slot couplers for the (2-4) GHz range as well as prototype measurements with protons in the COSY accelerator will be presented. | ||
| THPP056 | Simulations of Incoherent Vertical Ion Losses and Cooling Stacking Injection | 3494 |
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| The cooling stacking injection at a synchrotron is applied to obtain a high intensity of the stored coasting ion beam. The efficiency of cooling-stacking injection is defined mainly by two parameters: the cooling-accumulation efficiency and the ion life time. The life time of new injected ions usually is essentially smaller than the stack life time for high intensive ion beams. The incoherent loses of new injected ions are related to a multi scattering on residual gas atoms and a vertical heating caused by ion stack noise. The short life time of new injected ions restricts the efficiency of the cooling stacking injection The life time of new injected C6+ ions is shorter by 2 times than stack life time at HIMAC cooling stacking injection. The life time of new injected protons in S-LSR is smaller by 2-3 orders of magnitudes than the stack life time. The analytical estimations and BETACOL simulations of vertical incoherent ion losses and cooling stacking injection are presented. | ||
| THPP057 | Electron Cooling Experiments at LEIR | 3497 |
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| The LEIR electron cooler is the first of a new generation of coolers utilising high-perveance variable-density electron beams for the cooling and accumulation of heavy ion beams. It was commissioned at the end of 2005 and has since been routinely used to provide high brightness Pb ion beams required for future LHC ion runs. High perveance, or intensity, is required to rapidly reduce the phase-space dimensions of a newly injected “hot” beam whilst the variable density helps to efficiently cool particles with large betatron oscillations and at the same time improve the lifetime of the cooled stack. In this report we present the results of recent measurements made to check and to better understand the influence of the electron beam size, intensity and density profile on the cooling performance. |