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Iwamoto, Yosuke; Yoshida, Makoto*; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Yashima, Hiroshi*; Yabuuchi, Atsushi*; Kinomura, Atsushi*; Shima, Tatsushi*
JPS Conference Proceedings (Internet), 28, p.061003_1 - 061003_5, 2020/02
To predict the lifetime of target materials in high-energy radiation environments at spallation neutron sources, radiation transport codes such as PHITS are used to calculate the displacements per atom (DPA) value. In this work, to validate calculated DPA values of tungsten, we implemented 0.25-mm-diameter wire sample of tungsten in a proton irradiation device with a Gifford-McMahon cryocooler and measured the defect-induced electrical resistivity changes related to the displacement cross section using 389-MeV protons at 10 K. In comparison with experimental data under 1.1 and 1.9 GeV proton irradiation, we found that damage rate of tungsten increases with proton energy due to increase the number of secondary particle s produced by nuclear reactions.
Abo, Satoshi*; Mokuno, Yoshiaki*; Kinomura, Atsushi*; Onoda, Shinobu; Hirao, Toshio; Oshima, Takeshi; Iwamatsu, Toshiaki*; Takai, Mikio*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.183 - 186, 2008/12
no abstracts in English
Sakai, Hiroaki; Minei, Shuntaro; Hirade, Tetsuya; Oshima, Nagayasu*; Kobayashi, Yoshinori*; Kinomura, Atsushi*; Suzuki, Ryoichi*
no journal, ,
It was reported that positronium (Ps) formation probability was enhanced very much with very high electric fields. The spur reaction model can not explain this Ps formation. We tried to investigate this Ps formation with high electric fields in polyimide (kapton) that has no Ps formation with no electric field. Then we found out that Ps formation was not possible even at high electric fields. However, the annihilation lifetime of free positrons was elongated and it was probably caused by the positron drift movement.
Sakai, Hiroaki; Minei, Shuntaro; Hirade, Tetsuya; Oshima, Nagayasu*; Kobayashi, Yoshinori*; Kinomura, Atsushi*; Suzuki, Ryoichi*
no journal, ,
It was reported that the positronium (Ps) formation in polymers was enhanced near breakdown voltage. It cannot be explained by the Spur Reaction Model. We investigated the electric field effect on positron annihilation lifetime for Kapton that has no Ps formation. We observed elongation of the free positron annihilation lifetime instead of the enhancement of Ps formation. It is possible to explain that drift of positrons causes smaller annihilation probability, i.e. longer lifetime. Now it is possible to explain the Ps formation enhancement reported previously could be caused by the elongation of the lifetime of the free positrons.
Sakai, Hiroaki; Minei, Shuntaro; Hirade, Tetsuya; Oshima, Nagayasu*; Kobayashi, Yoshinori*; Kinomura, Atsushi*; Suzuki, Ryoichi*
no journal, ,
It was reported that psoitronium (Ps) formation probability in polymers under high electric fields were enhanced. The spur reaction model explaining Ps formation in insulating materials cannot be applied for the enhancement under high electric fields. Then we studied the Ps formation mechanism under high electric fields by observing positron annihilation lifetime in Kapton (polyimide) that does not have any Ps formation. Then Ps was not formed even under high electric fields and the elongation of the lifetime of the positrons free from Ps formation. The elongation of the lifetime of the positron and Ps formation enhancement could not be judged by the methods applied in the previously reports.
Toyama, Takeshi*; Inoue, Koji*; Nagai, Yasuyoshi*; Kinomura, Atsushi*; Suzudo, Tomoaki; Hatano, Yuji*
no journal, ,
Tungsten (W) is promising as a fusion reactor plasma facing material. Retention and accumulation of hydrogen isotopes become a problem under irradiation, but it was found that the amount of hydrogen isotope accumulation is significantly reduced by the addition of rhenium (Re) and chromium (Cr). This is thought that Re and Cr suppress the formation of vacancy-type defects under irradiation, which are hydrogen trapping sites, but sufficient experimental findings to support this phenomenon have not been obtained yet. The purpose of this study is to apply the positron annihilation method and to investigate the effect of additive elements on the formation of irradiation defects in W alloys under electron beam and neutron irradiation.
