大電流衝突型加速器KEKBにおける可動マスクの改良と今後の方向 [in Japanese] Experiences and Future Plans of Movable Mask System for the High Current Collider KEK B-factory [in Japanese]
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The movable mask is a special device for an accelerator that cuts off spent particles near the beam orbit and reduces background of the detector. For the KEKB, an electron/positron collider with two rings, sixteen movable masks had been installed for each ring. The originally designed masks, however, revealed severe troubles of heating, arcing and vacuum leaks at the stored beam currents of several hundreds mA. Several kinds of improved masks had been designed employing RF technologies and were installed to the ring step by step. The latest masks are working well except for the grooves on the mask head. Here the problems of movable masks so far are summarized and the structures of the latest movable masks and their status are presented.
Shinku 45(3), 157-160, 2002-03-20
The Vacuum Society of Japan