No abstract available

[en] We report a new method of measuring the absolute ionization efficiency of an ion source, which is independent of gas flow rate fed to an ionizer and of detection efficiency of the resulting ions. The method is based on the fact that when a pulsed alternate potential is applied between the ionizer and an electrode set outside near its exit hole, ions stored inside the ionizer while the potential is repulsive for the ions are flushed out as soon as it becomes attractive. It is shown that when the duty factor and repetition rate of the applied potential are properly chosen, the magnitude of this bunching effect can simply be expressed only by the ionization efficiency. Since its magnitude can quickly be evaluated, for example, by observing the time dependence of the bunched ion current in an oscilloscope, it provides a simple and reliable way for on-line diagnostics of the source. (author)

[en] Radiocesium deposited in the forest canopy is transferred to the forest floor by rainwater and litterfall. Among them, stemflow likely increases the radiocesium inventory by concentrating rainwater around the trunk. However, the effects of stemflow on the influx of radiocesium into forest soil have not been evaluated quantitatively. In this study, the fluxes of rainwater via stemflow, throughfall, and soil infiltration water were observed. The concentration of dissolved 137Cs was measured in a cedar forest in Fukushima Prefecture, Japan. Soil infiltration water was collected at 5 cm and 20 cm depths at the distant point from the tree trunk (Bt), and the base of the tree trunk (Rd), where the influence of stemflow was strong. The observations were conducted during the period from September 2019 to November 2021. During the observation period, an experiment was conducted to intercept the inflow of rainwater via the throughfall or stemflow, and the change in soil infiltration water was observed. The observation results showed that the infiltration flux of radiocesium into the forest soil was significantly higher at the Rd site and about three times larger than at the Bt site. Particularly at the 20 cm depth at the Rd site, the soil infiltration water flux increased with the stemflow. The stemflow exclusion resulted in the dcrease of radiocesium flux by about 70% at all depths at the Rd site. These results suggest that the stemflow increases the input of radiocesium to the base of the tree trunk and facilitates its transfer to the deeper soil layers.

[en] An EMIS facility has begun operation at one of the beam lines of a multipurpose cyclotron of K = 50 MeV. The separator is of a Scandinavian type of 55⁰ deflection and 1500 mm dispersion. During developments of the target-ion sources and tape transport system, the on-line test experiments have been performed, and several short-lived nucleis of Zn, Cu, Se and K were identified. The outline of ISOL experimental system and the results of decay of Tsub(z) = - 1/2 nuclide ⁵⁹Zn are reported, and the fsub(t)- value, the Gamow-Teller matrix element and the mass of ⁵⁹Zn are discussed. The future plan of the development of targetion source system and the ISOL experiment are also described. (author)

[en] The AVF cyclotron at CYRIC has been replaced from K=50 MeV AVF cyclotron to K=130 MeV AVF cyclotron. All of the missions for replacement have been almost completed. It has started the commissioning for beam tuning and has partly been opened for experiments. Outline of the new plans by the new cyclotron will be presented including the RI beam projects under consideration. (author)

[en] Total cross sections and angular distributions in the ⁶Li(p, ³He)⁴He reaction have been measured over the energy range Esub(p) = 100-700 keV. The extrapolation of the cross section to the energy region which is of interest in controlled thermonuclear reactors is given. The values of the 'astrophysical S-function' are deduced from the cross sections. (Auth.)

No abstract available

[en] The status of the ion-guide isotope separator on line at the Tohoku University Cyclotron is reported. Using the present ion-guide system together with a ΔE-E plastic counter telescope and germanium detector we identified 16 short-lived nuclei including firstly mass separated nuclei; ⁵⁷Cu, ⁴⁵V and so on. The efficiency of mass separation was ε ∼1 %, where ε is defined as the number of atoms collected at the end of the separator divided by that recoiling from the target. Application of IGISOL to nuclear physics is being performed for nuclei in the f_7/2-p3/2 shell regions and medium mass neutron-rich nuclei produced by proton-induced fission reaction with a uranium target. (author)

[en] Published in summary form only

[en] In Japan's forests, field data on the distribution and migration of radiocesium deposited by the Fukushima Daiichi Nuclear Power Plant accident, from the initial dynamics to the distribution in the forest over ten years, have been vigorously collected. The results have been published in an IAEA technical report (IAEA- TECDOC-1927, 2020) as a database of migration parameters to be compiled by an international project (MODARIA II: Modelling and Data for Radiological Impact Assessments) promoted by the International Atomic Energy Agency (IAEA). Radiocesium's transfer mechanisms in the forest by hydrological processes and the runoff through the water system were summarized based on investigations in experimental forests and watersheds in Fukushima Prefecture. Besides, we outlined the missing links that need to be clarified by re-analysis of existing data and additional experiments based on previous studies on Fukushima and Chernobyl. Finally, we discussed the direction of future monitoring surveys.