Tuning & Study ( Accel. & BL ) Injection Failure User Time 304 50 26 906 1457.6 110 110 2512 1624.2 95.2 57.2 3275 1815 70.4 88.7 3193.4 1276.5 59.3 87.1 4033.2 1997 1998 1999 2000 2001 0 1000 2000 3000 4000 5000 6000 1286 4189.6 5051.6 5167.5 5456.1 Tuning & Study Injection Failure User Time Fig. 1. Operational statistics since the inauguration. The operational statistics since the inauguration are shown in Fig. 1 . In 2001, the SPring-8 storage ring was operated in three- or four-week period for o n e o p e r a t i o n c y c l e . T h e t o t a l o p e r a t i o n t i m e o f a c c e l e r a t o r c o m p l e x w a s 5 4 5 6 . 1 h o u r s . A b o u t 74% of the operation time was available to users. The injection time and the down time due to failure accounted for 1.1% and 1.6% of the operation time, respectively. The remaining 23.4% was dedicated f o r : ( i ) t h e m a c h i n e a n d b e a m l i n e s t u d y , ( i i ) t h e m a c h i n e a n d b e a m l i n e t u n i n g , ( i i i ) t h e c o m m i s s i o n i n g of new beamlines. Th e op er at io n mo de s of th re e di ff er en t fi ll in g patterns were delivered to the user time; 37.8% in the multi-bunch mode, 38.9% in the several bunch m o d e s u c h a s 2 0 3 - b u n c h m o d e ( 2 0 3 e q u a l l y spa ced bun che s) and 84 equ all y spa ced 4-b unc h trains, and the remaining 23.3% in the hybrid filling m o d e s u c h a s a 1 / 1 2 - p a r t i a l l y f i l l e d m u l t i - b u n c h with 10-isolated bunches. In 2001, several-bunch m o d e h a s b e e n o n t h e i n c r e a s e . F o r t h e h y b r i d filling mode, 1 or 1.5 mA is stored in each isolated bunch. A purity of isolated bunch better than 10 -9 is routinely being delivered. T h e o p e r a t i o n s c h e d u l e f o r t h e a c c e l e r a t o r c o m p l e x i s u s u a l l y f i x e d s e m i a n n u a l l y . T h e s e se mi an nu al te rm s ar e re fe rr ed to as th e re se ar ch t e r m s f o r u s e r s , t h e f i r s t a n d s e c o n d h a l v e s o f w h i c h a r e d e n o t e d a s x x x x A a n d x x x x B , r e s p e c t i v e l y . I n t h e f i r s t t h r e e y e a r s a f t e r t h e i n a u g u r a t i o n o f S P r i n g - 8 , t h e r e s e a r c h t e r m w a s d e f i n e d o n t h e basis of the Japanese fiscal year. From the year of 20 00 , ho we ve r, th e re se ar ch te rm ha s be en de fi ne d on a calendar year basis for the smooth scheduling with the Proposal Review Committee members. In the past four years, the SPring-8 accelerator complex has experienced long-term shutdowns for two months in summer and one month in winter in o r d e r t o i n s t a l l i n s e r t i o n d e v i c e s a n d f r o n t - e n d components for new beamlines. 116
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