| 摘要 |
PURPOSE:To discriminate and measure alpha ray and beta ray without complicated devices by switching a low-bias power supply and a high-bias power supply, and changing a voltage, which is applied on a semiconductor element. CONSTITUTION:A voltage is applied on a detecting element 1 from a low-bias power supply 3 and amplified with an amplifier 5. The ratio between the wave crest of a pulse caused by alpha ray and the wave crest of a pulse caused by betaray becomes about 10:1. Therefore, the threshold value of the wave crest of the pulse is set, and the part caused by the beta ray is cut with a comparator 6. Then, only the alpha ray, from which energy is lost, can be measured. Then, a switch 2 is changed by the bias switching signal from a microcomputer 7 at the outside of a detector 109, and a voltage is applied from a high-bias power supply 4. The signal of energy higher than thermal noise is measured. Thus, the rays, which are made to pass through a depletion layer or absorbed with the depletion layer, and the alpha ray, whose energy is lost, are measured. The measured result of the alpha ray is subtracted with the microcomputer 7. Then, the measured result of only the alpha ray is obtained.
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