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Tamakuma, Yuki*; Yamada, Ryohei; Suzuki, Takahito*; Kuroki, Tomohiro*; Saga, Rikiya*; Mizuno, Hiroyuki*; Sasaki, Hiroyuki*; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*
Radiation Protection Dosimetry, 184(3-4), p.307 - 310, 2019/10
Times Cited Count：1 Percentile：10.81(Environmental Sciences)After the Fukushima Daiichi Nuclear Power Plant accident, the radiation dose for first responders was not evaluated accurately due to lack of the monitoring data. It has been important to evaluate a radiation dose for workers in emergency response at a nuclear accident. In this study, a new device which can evaluate both of external and internal exposure doses was developed and the performance of various environmental radiation monitors including commercially available monitors were tested and compared from the viewpoint of an environmental monitoring at emergency situation. Background counts of the monitors and the ambient dose equivalent rate were measured in Fukushima Prefecture. The detection limit for beta particles was evaluated by the method of ISO11929. The sensitivity for gamma-rays of the dust monitor using a ZnS(Ag) and a plastic scintillator was high, but that of the external exposure monitor using a silicon photodiode with CsI(Tl) crystal was relatively low. The detection limit ranged 190-280 Bq m
at 100 
Sv h
, exceeding the detection limit of 100 Bq m in the minimum requirement by the National Regulation Authority in Japan. Use of the shielding with lead is necessary to achieve the minimum requirement. These results indicate that the dust monitor using a ZnS(Ag) scintillator and a plastic scintillator is suitable for the external exposure monitor and the developed internal exposure monitor is for the internal exposure monitor at emergency situation among the evaluated monitors. In the future study, the counting efficiency, the relative uncertainty and the performance of the detection for alpha particles will be evaluated, and it will be considered which type of a monitor is suitable after taking the portability into account.
Shikazono, Naoya; Suzuki, Chihiro*; Kitamura, Satoshi; Watanabe, Hiroshi*; Tano, Shigemitsu*; Tanaka, Atsushi
Journal of Experimental Botany, 56(412), p.587 - 596, 2005/02
Times Cited Count：117 Percentile：91.08(Plant Sciences)no abstracts in English
mutants of induced by carbon ionsShikazono, Naoya; Yokota, Yukihiko*; Kitamura, Satoshi; Suzuki, Chihiro*; Watanabe, Hiroshi; Tano, Shigemitsu; Tanaka, Atsushi
Genetics, 163(4), p.1449 - 1455, 2003/04
Irradiation of by carbon ions was carried out to investigate the mutational effect of ion particles in higher plants. Frequencies of embryonic lethals and chlorophyll deficient mutants were found to be significantly higher after carbon ion-irradiation than after electron-irradiation (11-fold and 7.8-fold per unit dose, respectively). During the isolation of mutants, two new classes of flavonoid mutants (
) were isolated from carbon ion-mutagenized M2 plants. From PCR and sequence analysis, two of the three 
mutant alleles were found to have a small deletion within the 
gene and the other was revealed to contain a rearrangement. Using the segregation rates, the mutation rate of carbon ions was estimated to be 17-fold higher than that of electrons. The isolation of novel mutants and the high mutation rate suggest that ion particles can be used as a valuable mutagen for plant genetics.
