A semiconductor film serving as an active region of a thin film transistor and an upper oxide film protecting the semiconductor film are dry etched to form the active region. The bearing housing of the pivoting bearing comprises two bearing housing parts, and each bearing housing part comprises a part flange. The dummy memory cell includes first and second wirings respectively corresponding to the power supply wiring and the ground wiring and extending in the direction of the word line; and two sets of a dummy load circuit and a dummy drive transistor, wherein the two sets are connected with the first and second wirings, which are biased to prevent leakage current from flowing. The accelerator system is a non-scaling fixed field alternating gradient particle accelerator.