| 摘要 |
PURPOSE:To reduce a background noise and enlarge a counting rate by continuously providing a latter part secondary electron multiplication means, in which plural independent type diodes are continuously provided, on the latter part of the first part secondary multiplication means consisting of an en bloc formed diode for being made en bloc. CONSTITUTION:The first part secondary electron multiplication tube 20 having a tube path, which is continuously formed in S-shape, is arranged in the first part and later the latter part secondary electron multiplication tube 30 continuously connected alternately in multistages having its curved surface inside, and thereby, one secondary electron multiplication tube 40 is formed en bloc. Consequently, the opposing defects of the secondary electron multiplication tube 30 being said to be of a multistaged diode type having many background noises but an enlarged counting rate, and the secondary electron multiplication tube 20 of a continuous diode type having few background noises but not enlarged counting rate can be cancelled to some extent. Thereby, a background pulse can be reduced while the counting rate can be enlarged.
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