Patent ID: 8586942

Claim:
A beam position monitor that performs calculation processing of the state of a charged particle beam that has been accelerated by an accelerator and scanned by a scanning electromagnet, the beam position monitor comprising: a plurality of position monitors that detect a passing position of the charged particle beam through a plurality of detection channels; and a beam data processing device that performs calculation processing of the state of the charged particle beam, based on a plurality of analogue signals outputted from the plurality of position monitors, wherein the beam data processing device includes a plurality of channel data conversion units that perform AD conversion processing in which each of the plurality of analogue signals outputted from the position monitors is converted into a digital signal; a position size processing unit, for each of the position monitors, that calculates a beam position, which is a passing position of the charged particle beam in the position monitor, based on a plurality of voltage information items obtained through processing by the plurality of channel data conversion units; and an integrated control unit that controls the plurality of channel data conversion units in such a way that while the charges particle beam is irradiated onto an irradiation subject, the AD conversion processing is performed at different timings for the respective position monitors.