546. 高比放射能Ir-192線源の製造法

抄録

When preparing ¹⁹²Ir γ-ray source, there is a serious effect of neutron selfshielding during the irradiation. In order to avoid this effect, thin discs separated from each other were irradiated in capsule and after irradiation, they were piled one against the other to form a cylindrical source. This method should be applicable to the preparation of intense γ-ray sources with characteristics suitable for radiogrophic work.
Iridium discs, 0.2 and 0.4mm thick, were irradiated in the experimental hole of JRR-2, and the ¹⁹²Ir γ-ray dose from each disc and also of the built-up source was observed. In comparison with a 2mm dia. ×2mm thick source prepared in the conventional way, the γ-ray strength from the built-up source of the same overall size was larger by 2.3 and 1.6 times greater on sources made up of 0.2 and 0.4mm thick plates, respectively. Furthermore, the built-up source showed better radiographic quality than a conventional source of the same dimensions, its radioactivity being more homogeneously distributed through the source.