Detector

A detector comprising:

• a first electrode;
• a second electrode facing the first electrode with a space therebetween and forming a flow path for charged particles as objects to be detected between the first electrode and the second electrode;
• a third electrode arranged side-by-side with the second electrode on a downstream side in the flow path with respect to the second electrode and configured to collect the charged particles;
• and
• a potential supply circuit configured to supply a potential to at least one of the first electrode and the second electrode,
• wherein:
• the potential supply circuit includes a first inductor, including a first input portion and a first output portion, and a second inductor including a second input portion and a second output portion, the first inductor not being connected to the first electrode or the second electrode,
• the first input portion of the first inductor is connected to a DC power supply, and the DC power supply is not connected to the second inductor, and
• the second input portion of the second inductor is connected to the first electrode or the second electrode.