| 摘要 |
PURPOSE:To measure a radiation dose previously with a wide dynamic range by varying an integration time according to the level of a radiation detection output signal. CONSTITUTION:The output signal of a radiation detector 7 is integrated by an integrator 13, whose integral value is compared with a reference voltage V0 by a comparator 15. A counter 23 begins to count clock pulses from a reference clock generating part 17 on the start of the integration of the integrator 13 and an AND gate 21 is closed when the integral value reaches the V0, thereby stopping the counting operation. Count data is sent to an arithmetic control part to perform reciprocal arithmetic, finding the radiation dose. If the detection output of a detector 7 is small and the counter 23 overflows before the integral value reaches the reference value V0, a signal S5 is outputted through an FF 25, etc., to turn OFF the switch 13e of the integrator 13, so that the time up to when the integral value reaches the reference value V0 varies. Thus, the radiation dose is measured precisely with the wide dynamic range.
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