| 摘要 |
PURPOSE:To know a beam colliding place by radiating a beam once, by placing a coaxial cable on the outside periphery of a beam duct for turning round a particle, and detecting an ionization current flowing between a core wire of said coaxial cable and a shield, as time elapses. CONSTITUTION:A beam which has been radiated from a particle injecting device 1 is deflected by a deflecting magnet 3 and turns around a circular track in a beam duct 2. In one end A, a core wire 51 and a shield 52 are opened, and in the other end B, a coaxial cable 5 to which a battery E and a resistance R have been connected is provided so as to surround almost the whole periphery of the outside of the beam duct 2. A voltage drop generated in this resistance R is observed by an oscilloscope 6 as time elapses. As a result, a particle collides with a side wall of the beam duct 2, and in the coaxial cable in the vicinity of a place X where a radiant ray has been generated, an ionization current flows between the core wire and the shield, therefore, a pulse is detected at the time corresponding to a distance L extending from the collision point X to the end part B of the cable 5.
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