| 摘要 |
PURPOSE:To remarkably reduce a background discrete value, while maintaining the measurement efficiency of a body to be measured by providing a means for placing radioactivity detector itself in the inside of the body to be measured, and a transfer mechanism being a means which can transfer successively the body to be measured being a crushing body to its periphery. CONSTITUTION:In the constitution for placing a body 1 to be measured in the outside periphery on the coaxial periphery centering around a detector 2 and transferring it, the body 1 to be measured itself has an effect for shielding an external radiant ray, and thickness of a shielding body can also be thinned. By using a mechanism for transferring successively the body to be measured to the periphery of the detector and executing the measurement, a very low level can be measured, and by reducing a background discrete value, the lower limit value of the measurement can be improved by one digit or above. Also, the detector is provided by non-contact and independently from an inner cylinder 81 of the transfer mechanism of the body 1 to be measured. In such a way, a noise signal caused by vibration of the radiation detector 2 can be eliminated, and the lower limit value of detection can be improved.
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