| 摘要 |
PURPOSE:To improve the sensitivity of a detector by providing a junction field- effect transistor for using only a single gate in the input stage of a current- voltage converter for converting a current signal from a ray sensor into a voltage signal. CONSTITUTION:An ray sensor 1 outputs pulse current (i) by means of incidence of rays. Output current (i) is converted into a pulse voltage signal (v) by the use of a current-voltage converter 2. That is to say, the current-volage converter 2 is equipped with a junction field-effect transistor (a) son the input stage thereof, and the output power (i) from the ray sensor 1 is supplied in a gate. Further, the source of a junction field-effect transistor 2a is earthed, and drain is connected to the input of an amplifier 2b. And 2c represents feedback resistance and 2d indicates a capacitor for current integral. Next, the voltage signal (v) is amplified by the use of an amplifier 3 and introduced in a counter and the like as a detecting signal. Therefore, the input capacity can considerably be reduced, and the sensitivity of the detector can be improved.
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