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Title |
Page |
| TUPC096 |
Development of Beam Loss Monitor for the SPring-8 Storage Ring
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1284 |
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- Y. Shimosaki, K. Kobayashi, M. Oishi, M. Shoji, K. Soutome, Y. Taniuchi
JASRI/SPring-8, Hyogo-ken
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A beam loss monitor using PIN photodiodes has been developed. To check its performance, we installed it at an in-vacuum insertion device and at the injection section in the SPring-8 storage ring. Information on the beam loss at these points will be useful for examining demagnetization of permanent magnets of insertion devices and for studying a mechanism of beam loss. A noise level at these points is however high due to stray synchrotron radiation, an induction voltage generated by pulsed injection magnets, etc. The beam loss signal is then picked up under a high noise condition. Experimental results with its countermeasure will be reported.
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| THPC070 |
Symmetry Restoration of the SPring-8 Storage Ring by Counter-sextupole Magnets
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3149 |
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- K. Soutome, S. Daté, T. Fujita, K. Fukami, C. Mitsuda, A. Mochihashi, H. Ohkuma, M. Oishi, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, K. Tsumaki, H. Yonehara, C. Zhang
JASRI/SPring-8, Hyogo-ken
- S. Matsui, H. Takebe, H. Tanaka
RIKEN/SPring-8, Hyogo
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In the SPring-8 storage ring there are four magnet-free long straight sections of about 30m. These were realized in 2000 by locally rearranging quadrupole and sextupole magnets. In modifying the optics we took care of the periodicity of cell structure, especially of sextupole field distribution along the ring. To keep the periodicity high and hence the dynamic aperture large, we adopted a scheme in which "betatron phase matching" and "local chromaticity correction" are combined. In this scheme the dynamic aperture for on-momentum electrons is kept by the phase matching and that for off-momentum electrons is enlarged by the local chromaticity correction with weak sextupoles (SL). After modifying the lattice, we tried to recover the symmetry of the ring further and found that a harmful effect of nonlinear kick due to SL can be minimized by additional "counter-sextupole magnets" placed 180 degrees apart in horizontal betatron phase from SL. We installed such counter-sextupoles in every long straight sections and confirmed that the aperture was improved. In the paper we discuss these topics showing experimental data of injection efficiency, momentum acceptance, etc.
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