Status of JSNS shutter system; 4-years operation and upcoming improvement

Oikawa, Kenichi   ; Takada, Hiroshi   ; Ogawa, Akira; Tanaka, Hiromichi; Maekawa, Fujio  

Japan Spallation Neutron Source provides 23 beam-lines for the neutron experiments in MLF, and each beam-line has an independent primary shutter. Meanwhile, the SNS at U.S. has 24 beam-lines, but they have 12-single channel shutter blocks and 6-multichannel shutter blocks. We realized independent shutter operation for every instrument in JSNS by proper shielding design of the target station and a compact mechanical design of the driving system of the primary shutter. We summarize the status of JSNS shutter system from May 2008 to July 2012 operation, some trouble and their recovery work. In addition, we are facing a Single Event Effect due to the high-energy neutron at the encoder of the servo-moter system. Upcoming improvement in next year will be presented.