| 摘要 |
PROBLEM TO BE SOLVED: To provide an ion detector and an electron multiplier having few false signals caused by gas molecules while preventing an accident caused by touching wiring or the like when replacing the electron multiplier. SOLUTION: This ion detector 1 has the electron multiplier 22, and the electron multiplier 22 has a recessed metallic fixing plate 21 and an electron multiplier body 20. The recessed metallic fixing plate 21 is formed in recessed cross- sectional shape having a back face 21A and parallel sides 21B, 21C vertically extending from the back face 21A. The electron multiplier body 20 has a pair of insulating plates 23, 24 provided parallel with each other; a first dynode electrode group 26 comprising a plurality of dynode electrodes supported at both ends by a pair of insulating plates 23, 24 and fixed being aligned in line; and a second dynode electrode group 27 comprising a plurality of dynode electrodes fixed being aligned in line parallel with the first dynode electrode group 26. The electron multiplier body 20 is positioned being held between the sides 21B, 21C of the recessed metallic fixing plate 21. The insulating plates 23, 24 have openings 23a, 24a formed in the positions facing a space held by the first dynode electrode group 26 and the second dynode electrode group 27.
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