PROBLEM TO BE SOLVED: To achieve cost reduction of a radiation irradiator by downsizing a non-destructive monitor.SOLUTION: A radiation measuring apparatus 101 comprises: a high voltage power source 305 for applying voltage to high voltage application electrodes 402 and 404 an ionization chamber 301 which forms a first ionized layer between the high voltage application electrode 402 and a charge collection electrode 401 an ionization chamber 302 which forms a second ionized layer between the high voltage application electrode 404 and a charge collection electrode 403 and a signal processor 304 for integrating electric charge of ionized electrons reaching the charge collection electrodes 401 and 403, in which at least one partial region of the first ionized layer and the second ionized layer are overlapped. The radiation measuring apparatus 101 has a switch 701 for switching a connection destination of the signal processor 304 between the charge collection electrodes 401 and 403, and a switch 702 for switching a connection destination of the high voltage power source 305 between the high voltage application electrodes 402 and 404.COPYRIGHT: (C)2013,JPO&INPIT【課題】本発明によれば非破壊モニタの小型化により放射線照射装置の低コスト化を可能とする。【解決手段】高電圧印加電極402、404に電圧を印加する高電圧電源305と、高電圧印加電極402と電荷収集電極401との間に第一の電離層を形成する電離箱301と、高電圧印加電極404と電荷収集電極403との間に第二の電離層を形成する電離箱302と、電荷収集電極401、403に到達した電離電子の電荷を積算する信号処理装置304と、を備える放射線計測装置101において、前記第一の電離層と前記第二の電離層とは少なくとも一部の領域で重なり、信号処理装置304の接続先を前記電荷収集電極401と403との間で切り替えるスイッチ701と、高電圧電源305の接続先を高電圧印加電極402と404との間で切り替えるスイッチ702と、を有することを特徴とする。【選択図】 図3
