173 The operation statistics since the facility was opened to users are shown in Fig. 1. Before summer the shutdown in 2004, the SPring-8 storage ring was operated on four- or five-week period for one operation cycle. After the summer shutdown, the long-term operation cycle was started. The total operation time of the accelerator complex was 5759.2 hours, of which 79.7% (4590.9 hours) was made available to the users. In 2004, there was no injection time because top-up injection was being introduced. The down time due to failure accounted for 1.4% (82.4 hours) of the operation time; in October 2004, a great loss of user time was incurred due to an approaching typhoon, consequently, user time of 28.6 hours was canceled for the suspension of machine operation. The remaining 18.9% (1085.9 hours) was dedicated to (i) machine and beamline study, (ii) machine and beamline tuning, and (iii) the commissioning of new photon beamlines. The high availability (ratio of the net user time to planning user time) of 98.% was achieved. The operation modes of three different filling patterns were provided for the user time: 36.6% in the multi-bunch mode operation; 43.8% in the several- bunch mode such as the 203-bunch mode (203 equally spaced bunches) and 29 equally spaced 11-bunch trains; and the 19.6% in the hybrid filling mode such as a 1/12-partially filled multi-bunch with 10-isolated bunches. For the hybrid filling mode, 1 or 1.5 mA is stored in each isolated bunch. An isolated bunch purity of better than 10 -9 is routinely maintained in the top-up operation. Table I presents a summary of the useful beam parameters of the storage ring. The ring optics were returned to the former HHLV optics from October 2003. In September 2005, the low-emittance optics will be re-introduced to user time with a top-up operation by breaking the achromatic condition. )' Fig. 1. Operation statistics since the facility became available to users. Tunes ( x / y ) 40.15 / 18.35 40.15 / 18.35 Current[mA]: single bunch 13 10 multi bunch 100 (120 *1 ) 100 Bunch length (FWHM) [psec] 32 34 Horizontal emittance [nm • rad] 6.3 *2 / 6.6 *3 3.1 *2 Vertical emittance [pm • rad] 16.9 *3 8.7 *3 / 3.9 *4 Coupling [%] 0.26 *3 0.28 *3 / 0.13 *4 Beam size[ m]: ( x / y ) *5 Long ID section 381 / 13.4 283 / 11.4 ID section 397 / 8.5 289 / 7.2 BM section 149 / 21.0 103 / 15.2 Beam Divergence [ rad]: ( x’ / y’ ) *5 Long ID section 16.1 / 1.2 11.9 / 0.81 ID section 15.9 / 1.9 11.7 / 1.3 BM section 57.4 / 0.78 53.8 / 0.68 Operational Chromaticities: ( x / y ) +7 / +6 (+2 / +2) *6 +8 / +8 Lifetime [hr]: 100 mA (multi bunch) ~ 150 ~ 97 1 mA (single bunch) ~ 24 ~ 9 Dispersion distortion[mm]:horizontal (rms) 4 9.3 vertical (rms) 1.1 *7 1.1 *7 Orbit stability (tune harmonics)[ m]: horizontal (rms) – 1.3 vertical (rms) – 0.35 HHLV Optics Low Emittance Optics *1 Maximum stored beam current at machine study. *2 Measured by a pulse bump and scraper, *3 two dimensional interferometer, and *4 two photon correlation. *5 Assuming that 0.26% coupling for “HHLV” and 0.2% coupling for “Low Emittance Optics” *6 With bunch-by-bunch feedback. *7 With correction by 24 skew Q’s. Table I. Beam parameters of SPring-8 storage ring 1999 2002 2001 2000 1998 2003 1997 2004 Storage Ring Operation Time Tuning & Study (Accel. & BL) 1286 1270.6 4189.6 4135.4 5051.6 4863.9 5167.5 4972.9 5456.1 5340.6 5542.9 5484.1 5419.5 5328.5 6000 5000 4000 3000 2000 1000 0 Hours Failure User Time 26 906 110 2512 57.2 82.4 88.7 87.1 190.5 208.5 Accelerator Operation Time Injection Planning Time Availability (%) 304 1457.6 1624.2 1815 1276.5 1394.9 1245.8 5759.2 5736.7 1085.9 50 110 95.2 70.4 59.3 60.8 39.2 0 3275 3193.4 4033.2 3896.7 3926 4590.9 984 2712 3432 3352 4176 4152 4176 4680 97.2 96.7 98.2 97.4 98 95.3 95 98.1 Tuning & Study Injection Failure Failure UserTime
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