Charged particle detector

Abstract

This charged particle detector comprises: a channel-type first multiplication unit having a channel unit that emits electrons in response to incidence of charged particles, multiplies the emitted electrons, and emits the multiplied electrons; a discrete-type second multiplication unit that is disposed to face the first multiplication unit in a prescribed direction, and multiplies the electrons emitted from the channel unit of the first multiplication unit; and an anode that collects the multiplied electrons. The second multiplication unit includes a reduction unit formed such that, on at least one cross section along the prescribed direction, the width decreases toward the first multiplication unit in a direction orthogonal to the prescribed direction. The reduction unit has a pair of surfaces formed to approach each other closer toward the first multiplication unit on the cross section. The second multiplication unit multiplies the electrons that are emitted from the channel unit of the first multiplication unit and are incident on the pair of surfaces.

Claims

1. A charged particle detector comprising: a main body; a channel-type first multiplier having a main body and a channel formed inside the main body that emits electrons in response to the incidence of charged particles and multiplies and emits the emitted electrons; a discrete-type second multiplier arranged to face the first multiplier in a predetermined direction and multiplies the electrons emitted from the channel of the first multiplier; and an anode for collecting the multiplied electrons, wherein the second multiplier has a reduction portion formed in at least one cross section along the predetermined direction such that its width in a direction perpendicular to the predetermined direction decreases as it approaches the first multiplier; the reduction portion has a pair of surfaces formed in at least one cross section such that they approach each other as they approach the first multiplier; and the second multiplier multiplies the electrons emitted from the channel of the first multiplier and incident on the pair of surfaces.

2. The charged particle detector according to claim 1, wherein the pair of surfaces are inclined with respect to the predetermined direction in at least one cross-section such that they approach each other as they approach the first multiplication portion.

3. The charged particle detector according to claim 1 or 2, wherein the reduction portion includes a frustoconical portion whose apex faces the first multiplication portion, and the pair of surfaces are the surfaces of the frustoconical portion.

4. The charged particle detector according to claim 1 or 2, wherein the reduction portion has a uniform cross-sectional shape with respect to both the predetermined direction and the direction perpendicular to the predetermined direction.

5. A charged particle detector according to any one of claims 1 to 4, further comprising a support portion having electrical insulating properties and supporting the second multiplier portion on the opposite side from the first multiplier portion, wherein the second multiplier portion further comprises an extending portion extending from the reduction portion on the opposite side from the first multiplier portion, and the extending portion is supported by the support portion.

6. The charged particle detector according to any one of claims 1 to 5, further comprising a discrete third multiplier positioned opposite the pair of surfaces of the reduction portion and multiplying the electrons emitted from the second multiplier, wherein the anode collects the electrons multiplied in the third multiplier.

7. The charged particle detector according to claim 6, wherein the anode is located between the second multiplication unit and the third multiplication unit.

8. The charged particle detector according to any one of claims 1 to 7, wherein the anode has a mesh portion facing the pair of surfaces of the reduced portion.

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