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| MOPA23 | Performance of a Fast Kicker Magnet for Rare-RI Ring | 95 |
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We developed a fast kicker magnet for the Rare-RI Ring at the RI Beam Factory (RIBF) in RIKEN. The Rare-RI Ring is a storage ring developed to measure masses of unstable nuclei with a precision in the order of 10-6 *. The unstable nuclei are randomly produced in secondary beams by nuclear reactions of a DC primary beam from the RIBF accelerator complex, and their yields are as small as 1 event/day. Therefore, we apply the individual injection method to perform mass measurements of rare RI efficiently **. The developed kicker magnet is distributed constant type. The shape of magnetic field is essential to the individual injection, and the timing property is given by the inductance and capacitance components of the kicker. Based on results of simulations conducted for the equivalent electronic circuit, we optimized the electrodes and ferrite cores of the kicker. In June, we carried out the first commissioning of Rare-RI Ring using a 78Kr36+ beam with an energy of 167 MeV/nucleon. We succeeded in injecting and extracting particle-by-particle by using the kicker system. In this contribution, we will report details of the kicker magnet and will show the performance evidenced at the commissioning.
* A. Ozawa et al., Prog. Theor. Exp. Phys. 2012 (2012) 03C009. ** I.Meshkov et al.,Proceedings of EPAC 2004, Lucerne, Switzerland. |
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| MOPA24 | Performance of a Resonant Schottky Pick-up in the Commissioning of Rare-RI Ring | 98 |
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Rare-RI Ring *, ** is a storage ring dedicated for precise mass measurements of unstable nuclei to make clear the astrophysical r-process path. We employ the Isochronous mass spectrometry method in the order of 10-6. For precise tuning of the isochronous field, we developed a resonant Schottky pick-up which had a resonant cavity. We acquired the quantities by the offline test: shunt impedance, and unloaded quality factor. Using the quantities, we estimated the output signal power which is corresponding to a single ion with charge q on resonance ***. Comparing to thermal noise, present Schottky pick-up can detect a single ion with charge over 16. In June, we carried out the first commissioning of Rare-RI Ring using 78Kr38+ beam with the energy of 167 MeV/nucleon. By using the individual injection method with the fast kicker system, we succeeded in injecting, storing, and extracting 78Kr38+ ions. The Schottky pick-up successfully detected single 78Kr38+ ions. Also we confirmed that 78Kr38+ was stored for more than 2 seconds in a vacuum of 10-5 Pa. In this contribution, we will present recent status of the Schottky pick-up focusing on the results of the experiment.
* Y. Yamaguchi et al., Nucl. Instr. Meth. B 317 (2013) 629. ** A. Ozawa et al., Prog. Theor. Exp. Phys. 2012 (2012) 03C009. *** F. Nolden et al., Nucl. Instr. Meth. A 659 (2011) 69. |
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| WEPB02 | Electron-Beam-Driven RI Separator for SCRIT at RIKEN RI Beam Factory | 194 |
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The electron-beam-driven RI separator for SCRIT (ERIS)* was constructed for the SCRIT (Self-Confinement RI Target) electron scattering facility** at RIKEN RI Beam Factory, and it is employed to produce low-energy, high-quality, and high-intensity RI beams used for the electron scattering of unstable nuclei. In ERIS, the photofission of uranium driven by an electron beam is used for RI production, and the estimated production rate of fission products is 2.2*1011 fissions/s with 30-g uranium and a 1-kW electron beam. The RI production in ERIS has been operated since 2013. Uranium carbide is used as the production target, and it is obtained by the carbothermal reduction of uranium oxide in presence of carbon. The obtained disk was approximately 1 mm in a thickness and 18 mm in a diameter. The average mass concentration of uranium in the disk was estimated as 3.4 g/cm3. Recently, we improved the efficiency of release from the production target and that of transport from the target. As a result, the rate of 132Sn was 2.6*105 atoms/s with 15-g uranium and a 10-W electron beam. In this paper, we report improvements and the present status of ERIS.
* T. Ohnishi et. al: Nucl. Instr. Meth. B317, 357(2013). ** M. Wakasugi et. al: Nucl. Instr. Meth. B317, 668(2013). |
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| WEPB25 | Development of a Buffer Gas-Free Buncher for Low Energy RI Ion Beam | 253 |
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In the SCRIT (Self-Confining RI Ion Target) electron scattering facility* at RIKEN RI Beam Factory, we constructed an ISOL-type RI beam generator named ERIS (Electron-beam-driven RI separator for SCRIT)**. ERIS supplys continuous RI ion beam with the energy of 50 keV at maximum. In order to efficiently inject the RI beam into the SCRIT device equipped in an electron storage ring, it is necessary to provide a 500-us pulsed ion beam without deteriorating of a vacuum level of less than 10-7 Pa. Therefore, we are developing a buffer gas-free buncher system working under the ultra-high vacuum based on a linear radiofrequency quadrupole (RFQ) trap. Our idea is to make active use of the fringing field at the entrance and the exit to decelerate and stack ions continuously injected into the buncher. Experiment for the performance study is now going on using the stable 133Cs and 23Na ions. In this paper, we will report the latest status of the development and the study of the buncher.
*M. Wakasugi et. al, Nucl. Instr. Meth. B317, 668 (2013) **T. Ohnishi et. al, Nucl. Instr. Meth. B317, 357 (2013) |
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