| 摘要 |
<p>PURPOSE:To discriminate and measure gamma ray caused by an external irradiation use radiation source, and the gamma ray generated from an object to be measured itself, by measuring the density of the radioactive substance of the object to be measured, based on the difference of the first detecting value and the second detecting value, respectively. CONSTITUTION:At a usual time, the gamma ray is measured by a radiation detector 5, in a state that a shielding body 8 has been moved in front of an external irradiation use radiation source 3, namely, by cutting the gamma ray from the radiation source 3. In this case, transmission gamma ray 4 is not measured and only the gamma ray 6 emitted from an object to be measured 2 itself is measured. This measured value is the second detecting value. Subsequently, the shielding body 8 is moved only a short time so that the gamma ray 4 is made incident on the detector 5. In this case, the sum of the gamma ray 4 caused by the radiation source 3 and the gamma ray 6 generated from the object to be measured 2 is measured. This measured value is the first detecting value. Also, while a container 1 rotates, ascends and descends, said operation is repeated suitably. In this way, by measuring the density of the radioactive substance of the object to be measured, based on the difference of the first and the second detecting values, respectively, an exact measured value can be obtained.</p> |
