Ion detector

An ion detector comprising:

• an ion incidence portion;
• a conversion dynode disposed at a position where ions taken up through the ion incidence portion reach, the conversion dynode emitting secondary electrons in response to incidence of the ions;
• a dynode unit for cascade-multiplying secondary electrons emitted from the conversion dynode, the dynode unit being constituted by multiple stages of dynodes disposed along a predetermined electron multiplication direction;
• a first electron detection unit that includes a semiconductor detector having an electron multiplication function, the first electron detection unit being configured such that the semiconductor detector is disposed at a position where secondary electrons emitted from a final-stage dynode included in the dynode unit reach;
• a focus electrode disposed on a trajectory of secondary electrons which are directed from the final-stage dynode toward the first electron detection unit, the focus electrode having an opening for allowing passage of secondary electrons emitted from the final-stage dynode;
• a first support substrate on which an electrode unit including at least the conversion dynode, the dynode unit, and the focus electrode is mounted while being physically separated from at least the focus electrode;
• and
• a second support substrate disposed between the focus electrode and the first support substrate, the second support substrate having a surface on which at least the first electron detection unit is directly mounted.