Determination of specific ion positions of Cr³⁺ and O²- in Cr₂O₃ thin films and their relationship to exchange anisotropy at Co/Cr₂O₃ interfaces

The structures of antiferromagnetic Cr₂O₃(0001) thin films with perpendicular exchange bias were investigated using reflection high-energy electron diffraction, X-ray reflectivity, and synchrotron X-ray diffraction. We mainly investigated the specific ion positions of Cr³⁺ and O²- in the corundum structure and discussed their relationship to the magnetic anisotropy of Cr₂O₃. The Cr₂O₃(0001) thin film grown on a Pt(111) buffer layer exhibited a perpendicular exchange anisotropy density of 0.42 mJ/m², in which the Cr³⁺ position is the primary factor in the enhancement of magnetic anisotropy due to dipolar-interaction. In contrast, the single-crystalline Cr₂O₃(0001) film grown on a α-Al₂O₃(0001) substrate featured a low exchange magnetic anisotropy of 0.098 mJ/m². In this film, the Cr³⁺ position parameter is an insignificant factor, leading to low magnetic anisotropy. The O²- ion position also differs between the two types of films, which can affect both the magnetic anisotropy energy originating from fine structures and the magneto-electric properties of Cr₂O₃.Yu Shiratsuchi, Yuuta Nakano, Nobuhito Inami, Tetsuro Ueno, Kanta Ono, Reiji Kumai, Ryoko Sagayama, and Ryoichi Nakatani, Journal of Applied Physics 123, 103903 (2018); https://doi.org/10.1063/1.5020620

241Am as a Metabolic Tracer for Inhaled Plutonium Nitrate in External Chest Counting

The plutonium (Pu) treated in nuclear fuel cycle is usually accompanied with 241Am produced from 241Pu by b disintegration, which emits g-rays of 60 keV with the emission rate of 0.36, being more penetrable than the L X-rays from Pu. The 241Am could improve the detection limit of chest counting of Pu, if it being used as a metabolic tracer for Pu in lungs. Young adult male Wistar rats were exposed to polydisperse aerosols of Pu(NO3)4 with 0.6 mm in Activity Median Aerodynamic Diameter. They were periodically sacrificed and the radioactivity of 241Am and 238/239/240Pu in the autopsied lungs were measured. It has been shown that the 241Am was cleared from the lungs at nearly the same rate as the Pu at least for half a year post inhalation, which proved validity of 241Am as a metabolic tracer for inhaled Pu nitrate in external chest counting

Database of Calculated Values of Retention and Excretion for Members of the Public Following Acute Intake of Radionuclides

Workshop on Internal Dosimetry of Radionuclide

Database of Calculated Values of Retention and Excretion for Members of the Public Following Acute Intake of Radionuclides

Workshop on Internal Dosimetry of Radionuclide

Development of Software for Supporting Internal Dose Estimation

Recently developed biokinetic models of ICRP permit more realistic description of the behaviour of radionuclides in human body. This, however, has made the interpretation of bioassay data extremely difficult. Thus computer programs for implementing these models have become needed, but very few. The present work provides a PC software: MONDAL3 (Monitoring to Dose Calculation Ver.3) that enables users to estimate intake of radionuclides and resulting equivalent doses in tissues and effective doses delivered for various periods after the intake. The computation is carried out using the following models and parameters: - Respiratory tract model: ICRP Publication 66 - Biokinetic models: ICRP Publications 30, 56, 67, 69, 71 - GI tract model: ICRP Publication 30 - Dose coefficient: values given in ICRP CD-ROM. The input parameters for computation are as follows: - Choose a radionuclide among 42 radionuclides, which cover all radionuclides in ICRP Publications 54 and 78 - Choose an intake path between inhalation or ingestion - Choose a subject among ICRP reference workers or members of the public (3 mo, 1 y, 5 y, 10 y, 15 y or adult) - Choose an AMAD of aerosol particles among 0.1, 0.3, 1.0, 3.0, 5.0 or 10 microns for workers. For members of the public AMAD is fixed to 1.0 micron - Choose an absorption Type or f1 value of materials according to the assignment recommended in ICRP Publications 68, 71 and 72 - Choose an intake mode among acute, chronic or uneven chronic - Choose a measurement quantity for monitoring among whole-body or a specific organ content, or daily urinary or faecal excretion rate - Input a period of intake between 1 and 999 days - Input a measurement day after the last intake between 1 and 999 days - Input measured activity The following outputs are obtained as results of computation: intake activity of the radionuclide, committed effective dose, equivalent doses in tissues and effective doses delivered for various periods after intake. These results are printed out and saved to a text file together with the input data/conditions and comments made by the user. A graph is drawn which shows predicted values of the retention, urinary excretion or faecal excretion of radionuclide as a function of time following single intake of unit activity. The present software enables radiation officers, even if non-specialists, to estimate readily the intake and the resulting doses from measurement results of radioactivity in a whole body or in specific organs or in excreta.11th International Congress of the International Radiation Protection Associatio

Development of Software for Organ Dose Estimation at Radiation Emergency with Internal Contamination

At radiation emergency with heavy internal-contamination, prompt estimation of doses at specific organs is sometimes needed for planning clinical treatments. Recently developed biokinetic models of ICRP permit more realistic description of the behaviour of radionuclides in human body. This, however, has made the interpretation of bioassay data extremely difficult. Thus computer programs for implementing these models have become needed, but very few. The present work provides a PC software: MONDAL3 (Monitoring to Dose Calculation Ver.3) that enables users, even if non-specialists, to estimate readily intake of radionuclides and resulting equivalent doses in organs and effective doses at radiation emergency with internal contamination from measurement results of radioactivity in a whole body or in specific organs or in excreta.日本放射線影響学会第46回大