| 摘要 |
PURPOSE:To enable taking-out of a detection signal in a wide area from a direct-current area to a high frequenty area by providing an electron multiplier tube of continuous dinode type, a detection resistor, an amplifier and a means for taking a direct-current component from the output of the amplifier and feeding it back negatively. CONSTITUTION:A detection signal taken out as the change of voltage by the detection resistor 2 is amplified by two-level directly-connected amplifiers 6 and 7. And, a direct-current component in the output of the amplifier 7 is taken out through an integrating circuit 10 composed of a resistor 8 and a capacitor 9 and the direct-current component thus obtained is returned to the input of the amplifier 7 through the intermediary of a negative feedback amplifier 11. By this constitution, a negative feedback loop relating to the direct-current component is formed by the integrating circuit 10 and the amplifier 11 and, when the time constant of the integrating circuit 10 and the gain of the amplifier 11 are set properly, the fluctuation of the zero level of the detection signal obtained from the detection resistor 2 owing to the change of the resistance value of the electron multiplier tube of continuous dinode type 1 itself with the passage of time can be negated by the negative feedback loop, even when the level shows fluctuations. Therefore, the signal without any zero fluctuations can be taken out as the output of the amplifier 7.
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