Research Frontiers 2017 Research Frontiers 2017 104 It was the last year that SPring-8 celebrated the 20th anniversary since its start of operation in 1997. SPring-8 was stably operated throughout 2017 with the total operation time of the accelerator complex and the total user beam time of 5281.6 h and 4478.7 h, respectively, with the total down time of 29 h. SPring-8 had to complete all its operations by the middle of February 2018. Regarding its research proposal system, SPring-8 designated the Cross-SR Facility Use Proposals for Industrial Application as a priority field of the priority research program on 25 September 2017. Concerning the contract beamlines, there were five interim reviews conducted for Research Center for Nuclear Physics, Osaka University (BL33LEP I), and the project was authorized to continue. Upon the expiration of their contract terms, reviews were also conducted for SUNBEAM Consortium (BL16B2, BL16XU), Hyogo ID (BL24XU, Hyogo Prefecture), and their proposals for the next term were approved. At present, SPring-8 users number is as many as 13,000, all of whom are members of the SPring-8 User Community (SPRUC). It is important for SPring-8 to jointly organize scientific events with SPRUC, such as the SPring-8 S y m p o s i u m , t o f a c i l i t a t e d i a l o g u e b e t w e e n users and the facility staff. In 2017, the SPring-8 Symposium was held at Hiroshima University on September 4–5, with a participant number of 267. SPring-8 also accelerates communication between users and the industry. The Joint Conference on Industrial Applications of SPring-8 was held in Kawasaki on August 31 to September 1, 2017, with 258 participants. As part of its continuous effort towards fostering of human resources in synchrotron sciences, SPring-8 organized the 17th SPring-8 Summer School with 90 students of graduate schools nationwide, in cooperation with Hyogo University, Kwansei Gakuin University, the University of Tokyo, Okayama University, Osaka University, Japan Atomic Energy Agency, National Institutes for Quantum and Radiological Science and Technology, and RIKEN. Furthermore, SPring-8 and SPRUC organized the 1st SPring-8 Autumn School with 43 participants which included 3rd year university students and researcher of companies. The operation statistics for the last five fiscal years are shown in Fig. 1. In FY2017, the total operation time of the accelerator complex was 5281.6 h. The operation time of the storage ring was 5270.4 h, 85.0% of which (4478.7 h) was for SR experiments. This excellent figure of the user time represents a storage ring availability of 99.3%, and a remarkable availability higher than 99% has been accomplished throughout the last five fiscal years. The downtime resulting from failure accounted for 0.64% (28.7 h) of the total user time. The intensity of the light source, i.e., the stored current is kept extremely stable within 0.1% thanks to the top-up operation, in which the current is filled up at any time on demand. In 93.4% of the user time in FY2017 the stored current stayed at 100 mA by the top-up operation, but in 5.8% at 70 mA as a result of failure of the RF system. The variety of operation modes for SR experiments is one of the characteristics of SPring-8. The operation modes are grouped into several-bunch, and hybrid-filling modes. Several-bunch mode consists of equally spaced bunches or bunch-trains, i.e., 203 bunches, or 29 trains of 11 bunches, and hybrid-filling mode is composed of long bunch train and isolated single bunches as shown in Table 1, where a share of each operation mode is also shown. An isolated bunch impurity is routinely maintained better than 10 –8 in the top-up operation by the bunch cleaning in the booster. The bunch current is also kept constant within 1% by means of the top-up operation. In the operation of the “11/29-filling+1single bunch” mode in the 8th cycle, failure of the timing system incurred a shift of the injection timing signal by one RF bucket, and it disabled us from maintaining the 5 mA single bunch for about 40h. Table 2 summarizes the beam parameters of the storage ring. SPring-8 I. Introduction II. Machine Operation Research Frontiers 2017 Research Frontiers 2017 105 III. Beamlines The SPring-8 storage ring can accommodate up to 62 beamlines: 34 insertion devices, 4 long undulators, and 24 bending magnets. At present, 57 beamlines are in operation, covering a wide variety of research fields involving synchrotron radiation science and technology. The beamlines are classified into the following three types. (1) Public Beamlines (26 beamlines operating) (2) Contract Beamlines (19 beamlines operating) (3) RIKEN Beamlines (12 beamlines operating) There are now 26 public beamlines in full operation. The beamlines that are proposed and constructed by external organizations, such as universities, research institutes, private companies and consortiums, are called contract beamlines and are exclusively used by the contractors for their own research purposes. At present, 19 contract beamlines are in operation. The beamlines constructed by RIKEN except for public beamlines are called RIKEN beamlines, and are mainly used for RIKEN's own research activities, with partial availability for public use. RIKEN is now operating 12 beamlines. Fig. 1. Operation statistics for most recent five fiscal years. Table 1. Operation modes in FY2017 Table 2. Beam parameters of SPring-8 storage ring 0 1000 2000 3000 4000 5000 6000 Tuning Refill Down Time User Time Hours 4330.0 4265.4 898.0 3.5 20.0 213.0 3408.5 3432.0 99.3 5099.3 5080.7 1019.3 5.1 17.1 163.2 4057.8 4080.0 99.5 4817.9 4804.8 767.2 202.8 4033.9 4056.0 5281.6 5270.4 769.6 4.6 28.7 194.7 4478.7 4512.0 99.3 4951.7 4941.1 803.1 23.1 229.2 4125.5 4152.0 99.4 99.5 5.3 16.8 3.4 Refill Down Time Achieved User Time Planning User Time Availability (%) Accelerator Operation Time Storage Ring Operation Time Tuning & Study (Acc. & BL) Mean Time Between Failures FY2013 FY2014 FY2015 FY2016 FY2017 203 bunches 4 bunch-train × 84 11 bunch-train × 29 1/7-filling + 5 single bunches 2/29-filling + 26 single bunches 1/14-filling + 12 single bunches 4/58-filling + 53 single bunches Single bunch current (mA) Share of operation time (%) 18.1 7.4 20.7 8.0 3.2 14.4 6.4 3 1.4 1.6 1 11/29-filling + 1 single bunch 21.8 5 Energy [GeV] 8 Number of buckets 2436 Tunes ( / ) ν x ν y 41.14 / 19.34 Current [mA]: Bunch length ( ) [psec] σ 13 Horizontal emittance [nm • rad] 2.4 * single bunch 12 multi bunch 100 Vertical emittance [pm • rad] 4.8 * +2 / +2 * * * Coupling [%] 0.2 RF Voltage [MV] 14.4 * * ~ 16 Momentum acceptance [%] Beam size ( σ x / σ y )* [ μ m] Long ID section 333 / 7 ID section 316 / 5 BM1 section 94 / 12 3.2 ( ~ 256 MeV) BM2 section 100 / 12 Beam divergence ( σ x ' / σ y ' )* [ μ rad] Long ID section 8 / 0.7 ID section 9 / 1.0 BM1 section 58 / 0.5 BM2 section 68 / 0.5 Lifetime [hr]: Operational chromaticities ( ξ x / ξ y ) 100 mA (multi bunch) ~ 250 1 mA (single bunch) ~ 30 Horizontal dispersion [m]: Long ID section 0.153 ID section 0.146 BM1 section 0.039 BM2 section 0.059 Fast orbit stability (0.1 – 200 Hz) [ μ m] horizontal (rms) ~ 4 ~ 1 vertical (rms) * Assuming 0.2% coupling * * Power saving mode * * * With bunch-by-bunch feedback
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