| 摘要 |
PURPOSE:To attain to enhance gamma-ray detection efficiency as compared with a conventional method, by introducing gamma-rays to be measured into the semiconductive crystal of a circumferential part of a coaxial type semiconductive detector shifted from the center part of said detector. CONSTITUTION:A collimator plug 2 is arranged in front of a coaxial type semiconductive detector 11 and the collimator plug part 9 provided above the central oblique line part 12 of the coaxial type semiconductive detector 11 is shielded and a collimating hole 10 is provided to the circumference of said plug part 9 in a concentric circular form. The diameter of the collimating hole 10 is larger than that of the central electrode 5 of the coaxial semiconductive detector 11 and, therefore, gamma-rays passing through the collimating hole 10 is not incident to the central part 12 of the coaxial semiconductive detector 11 but incident to a peripheral semiconductive part 4. Therefore, the detection efficiency of gamma-rays to be measured becomes high and, especially, the detection efficiency of high energy gamma-rays becomes high.
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