| 摘要 |
PROBLEM TO BE SOLVED: To provide an improved technique to correct an error resulting from leakage current of an element. SOLUTION: An ionization chamber 10 generates ionization current by detecting radiation. An electrometer circuit 20 includes an operational amplifier OP1 for measuring the ionization current. A potential which is generated as the ionization current and the leakage current flow through a resistor R1 appears in an output terminal T1 of the operational amplifier OP1. A leakage current measuring circuit 30 includes an operational amplifier OP2 having equivalent characteristics to the operational amplifier OP1. A potential which is generated as the leakage current flows through a resistor R1 appears in an output terminal T2 of the operational amplifier OP2. A leakage current compensation circuit 40 functions as a subtracting circuit, and potential difference between the output terminal T1 and the output terminal T2 appears in an output terminal TO of an operational amplifier OP3. Thus, the leakage current component included in the output of the electrometer circuit 20 is removed. COPYRIGHT: (C)2008,JPO&INPIT
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