Patent Number: 
Section: abstract

Beam detectors configuring a beam monitor are connected to a single current measurement apparatus through respective switches. If a width of a beam incident hole of each of the beam detectors 32 in the X direction is Wf, a gap between the beam incident holes of adjacent beam detectors in the X direction is Ws, a beam width of the ion beam in the X direction is Wb, a total number of beam detectors is “p”, and “n” is an integer of 0≦n≦(p−2) and satisfying Wb<{n·Wf+(n+1)Ws}, a measuring process of receiving the ion beam by the beam monitor and measuring the waveforms of the beam currents flowing into the current measurement apparatus in a state in which the plurality of switches skipped by “n” are simultaneously switched ON and a switching process of switching the switches simultaneously switched ON under the condition, are repeated.