| 摘要 |
PURPOSE:To enable a constantly stable measurement to be automatically performed on even a nuclide having a short half-life by automatically obtaining an optimum applied voltage which corresponds to the change of the counting rate, and supplying the optimum applied voltage to each electrode by regulating high- voltage power sources. CONSTITUTION:The initial voltages of high-voltage power sources 6 and 8 are set by controlling manual voltage regulators 14 and 15. Next, when they are affirmed by voltmeters (M1) and (M2), the frequency of the electric discharge of a sample is counted in a spark chamber 1. Then, the counted value is fed to the input of a counting-rate detector 16, and the detector 16 delivers a signal corresponding to the counting rate of the spark chamber 1. Here, when a sample of a radioactive nuclide having a short half-life is measured in the spark chamber 1, the counting rate decreases with the lapse of time, the outputs of operation amplifiers (A1) and (A4) decrease as the counting rate decreases, and the set voltages of the power sources 6 and 8 decrease automatically. Thus, each electrode installed in the spark chamber 1 can be automatically supplied with an applied voltage which corresponds to the counting rate. |
