| 摘要 |
The present invention relates to an MCP unit or the like having a structure intended to achieve a desired time response characteristic, without depending on a limitation imposed by a channel diameter of MCP. The MCP unit comprises the MCP for releasing secondary electrons internally multiplied in response to incidence of charged particles, an anode arranged in a position where the secondary electrons reach, and an acceleration electrode arranged between the MCP and the anode. In particular, the acceleration electrode includes a plurality of openings which permit passing of the secondary electrons migrating from the MCP toward the anode. Further, the acceleration electrode is arranged such that the shortest distance B between the acceleration electrode and the anode is longer than the shortest distance A between the MCP and the acceleration electrode. Thus, an FWHM of a detected peak appearing in response to the incidence of the charged particles is remarkably shortened.
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