A compensation type calorimeter has been devised in order to measure the absorbed energy of various materials irradiated by electron beams of 1.5 Me V generated from a Van de Graaf type accelerator. The measurements made proved that the calorimeter served as a practical and satisfactory instrument for this purpose. Using 1.5 Me V electron beams, the energy absorption coefficient for polyvinyl chloride sheet of loo mg/cm2in thickness was found to be 9.8%, and the value was 12.1%, 7.2%, 9.4%, and 13.9% for polyethylene sheet, polyethylene powder, tetron sheet, and water, respectively. The spatial distributions of the energy dissipation of 1.5 Me V electron beams in polyvinyl chloride, polyethylene were also measured by the same method.
The C-V characteristics of MOS diodes were measured at the gate bias of 10, 0 and -10 V during the irradiation by60Co γ-rays. It is found that C/C0curves shift to more negative voltage with the increase of irradiation dose and saturate at about 3×106rads. The results are explained by introducing the assumption of donor centers which are formed probably by the mismatching between silicon and oxygen atoms in the oxide-silicon interface. The donor centers interact with the generated holes and make the trapped positive charge in the oxide-silicon interface. The formation of the trapped positive charge is studied by several bias conditions and the number of Nss is estimated.
The simple and rapid separation of recoiling arsenite-76As, which is produced by the neutron irradiation of arsenates, from the target was investigated by the thin-layer chromatographic method. The thin-layer plate was prepared by spreading“Wakogel B-5” silicagel containing 5% gypsum on a glass plate in 250μ thickness. Several developers were tested. By developing with acetone +conc. H3PO4 (10 : 1), As (III) with or without the carrier can be readily separated from As (V) in the developing time of 20-30 min.
X-ray films sandwiched between metacrylate plates were exposed through holes of a collimator vertically or horizontally to the gamma ray beam of131I kept in the place of NaI (T1) crystal instead. The results showed the leakage of gamma rays through 6 corners of weak shielding of a 5 cm focus collimator, which was built for the scanning of131I in tissues. However the leakage disappeared when the shielding was reinforced by inserting lead casts to the central holes. A 10 cm focus collimator showed a longer and narrower focus than the 5 cm focus collimators. This test does not need scanner, therefore the results are simple, reproducible, and useful for the comparison, and planning of collimators.
The effects of stable iodine and antithyroid drug were studied, in respect to a first aid at internal contamination accidents of radioiodine. Rats were given various doses of KI or methylthiouracil, changing intervals between the administration of131I and these drugs, and the thyroid uptake of131I was measured with a stand-type scintillation counter and the wholebody burden with an animal counter. By administrating 1.0mg/kg of KI or 10.0mg/kg of methylthiouracil, the thyroid uptake and the whole-body burden were decreased to about 10 and 30 per cent of the non-administered group, respectively. And in the case when longer interval had ellapsed after the intake of131I mathylthiouracil was found to be more effective than KI.