| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to exactly detect whether there are a prescribed or higher level of powdery particles in a supply hopper or not without any mechanical actions even in an atmosphere where the powdery particles are exposed to X rays. SOLUTION: Two X-ray measuring instruments 26a and 26b for measuring the dose of X rays 14 that originate from an electron beam irradiation area 12, penetrate a supply hopper 16 and enter an irradiation chamber container are located in upper and lower positions respectively in the side part, that of the supply hopper in the irradiation chamber container 2, opposite to the electron beam irradiation area 12. The doses Ia and Ib of X rays measured by each of the X-ray measuring instruments 26a and 26b are inputted into two comparators 28a and 28b placed outside the irradiation chamber container 2. The comparator 28a compares the dose Ia of X rays with a prescribed benchmark value Ra and outputs a detection signal Sa when the former Ia is not more than the latter Ra. Similarly, the comparator 28b compares the dose Ib of X rays mentioned above with a prescribed benchmark value Rb and outputs a detection signal Sb when the former Ib is not more than the latter Rb.
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