| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to minimize electric noises by making an insulative layer thick enough to hinder electric charges from moving between a collector electrode and a photoconductive layer. SOLUTION: A high direct-current voltage is applied between the first electrode 14 and an upper electrode 46 in order to supply a bias electric field to a radiation sensor 10, and when the voltage reaches a certain value, a switch of a switch element 18 is shut off. Then, the sensor 10 is exposed to X rays for a certain time and they are absorbed by a photoconductive layer 42. Since the second dielectric layer 40 exists between the photoconductive layer 42 and a collector electrode 36, electric charges do not flow. This makes it possible to minimize electric noises which usually degrade the efficiency of the sensor in the detection of radiation. The exposure of the sensor 10 to the X rays is stopped and the switch of the switch element 18 is turned on to detect electric charges of a condenser with an external integrating amplifier.
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