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Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Kuroki, Tomohiro*; Mizuno, Hiroyuki*; Yamada, Koji*; Furukawa, Masahide*; Tokonami, Shinji*
Perspectives in Science (Internet), 12, p.100414_1 - 100414_4, 2019/09
In this study, a portable radioactive plume monitor using a silicon photodiode was developed for the detection of a radioactive plume (e.g. 
I, 
Cs and 
Cs) in an emergency situation. It was found that the background count rate was proportional to ambient dose equivalent rate and the detection limit for the monitor at 20 
Sv h
as an ambient dose equivalent rate was evaluated to be 187 Bq m
using the ISO11929 method. These results suggest that the detection limit for the system can be decreased effectively by lead shielding with optimized thickness.
Takeuchi, Tomoaki; Shibata, Hiroshi; Hanakawa, Hiroki; Uehara, Toshiaki*; Ueno, Shunji*; Tsuchiya, Kunihiko; Kumahara, Hajime*; Shibagaki, Taro*; Komanome, Hirohisa*
JAEA-Technology 2017-026, 26 Pages, 2018/02
JAEA-Technology-2017-026.pdf:4.0MB
Under severe accidents, high-integrity transmission techniques are necessary so as to monitor the situation of the nuclear power plant. In this study, effects of gamma irradiation up to 10
Gy on properties of optical devices were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. After the irradiation, for the LEDs, the total luminous flux decreased and the browning of resin lenses occurred. Meanwhile, the current-voltage characteristics hardly changed. For the PDs, the light sensitivity decreased and the browning of resin window occurred. The dark currents of PDs did not become large enough to adversely affect transmission. These results indicated that both the decreases of the total luminous flux of the LEDs and the light sensitivity of the PDs were mainly caused by not the degradation of the semiconductor parts but the browning of the resin parts by the irradiation. In addition, basic decrease behaviors of light transmission of several different types of glasses by gamma irradiation were also obtained so as to select the suitable optical windows and filters for the developing radiation-resistant in-water wireless transmission system.
irradiationTakeuchi, Tomoaki; Otsuka, Noriaki; Uehara, Toshiaki; Kumahara, Hajime*; Tsuchiya, Kunihiko
QST-M-2; QST Takasaki Annual Report 2015, P. 80, 2017/03
no abstracts in English
Lohrmann, A.*; Iwamoto, Naoya*; Bodrog, Z.*; Castelletto, S.*; Oshima, Takeshi; Karle, T. J.*; Gali, A.*; Prawer, S.*; McCallum, J. C.*; Johnson, B. C.*
Nature Communications (Internet), 6, p.7783_1 - 7783_7, 2015/07
Times Cited Count：145 Percentile：96.84(Multidisciplinary Sciences)Oshima, Takeshi; Sato, Takahiro; Oikawa, Masakazu*; Onoda, Shinobu; Hirao, Toshio; Ito, Hisayoshi
Materials Science Forum, 527-529, p.1347 - 1350, 2006/00
Charge induced in 6H-SiC pn diodes by oxygen ion microbeams was examined in an energy range between 6 and 18 MeV. To minimize the influence of damage, single ion hit Transient Ion Beam Induced Current (TIBIC) measurement system, in which the transient current induced by single ion incidence can be measured, was used in this study. The value of charge increases with increasing reverse applied bias, and the saturation of charge is observed when the depletion layer becomes longer than ion range. An increase of collected charge by the funneling effect (the generation of a transient electric filed) is observed in the case of the depletion layer shorter than ion range. The charge collection efficiency is estimated to be 100 % in the saturation region (the depletion layer longer than ion range). It strongly suggests that high quality particle detectors are fabricated using SiC.
p diodes using transient ion beam-induced currentOshima, Takeshi; Sato, Takahiro; Oikawa, Masakazu*; Yamakawa, Takeshi; Onoda, Shinobu; Wakasa, Takeshi; Laird, J. S.; Hirao, Toshio; Kamiya, Tomihiro; Ito, Hisayoshi; et al.
Nuclear Instruments and Methods in Physics Research A, 541(1-2), p.236 - 240, 2005/04
Times Cited Count：9 Percentile：55.97(Instruments & Instrumentation)In order to develop particle detectors based on SiC semiconductor, SiC pn-diodes were irradiated with microbeam of 15MeV oxygen ions. The transient current was measured using the single ion hit transient ion beam induced current (TIBIC) system at TIARA. As the results, peak intensity of transient current induded by ion irradiation increased and falltime decreased with increasing applied bias. By the integration of transient current, the charge collection was estimated. It was found that charges generated in deeper region beyond the depletion layer can be collected by the funneling effect.
Onoda, Shinobu; Hirao, Toshio; Laird, J. S.; Okamoto, Tsuyoshi*; Koizumi, Yoshiharu*; Kamiya, Tomihiro
Nuclear Instruments and Methods in Physics Research B, 231(1-4), p.497 - 501, 2005/04
Times Cited Count：3 Percentile：30.27(Instruments & Instrumentation)no abstracts in English
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu; Wakasa, Takeshi; Yamakawa, Takeshi; Abe, Hiroshi; Oyama, Hidenori*; Kamiya, Tomihiro
JAERI-Review 2004-025, TIARA Annual Report 2003, p.14 - 16, 2004/11
no abstracts in English
Oshima, Takeshi; Sato, Takahiro; Oikawa, Masakazu*; Yamakawa, Takeshi; Onoda, Shinobu; Wakasa, Takeshi; Laird, J. S.; Hirao, Toshio; Kamiya, Tomihiro; Ito, Hisayoshi; et al.
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.177 - 180, 2004/10
no abstracts in English
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu; Wakasa, Takeshi; Yamakawa, Takeshi; Abe, Hiroshi; Kamiya, Tomihiro; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.125 - 129, 2004/10
no abstracts in English
Onoda, Shinobu; Hirao, Toshio; Laird, J. S.; Wakasa, Takeshi; Yamakawa, Takeshi; Okamoto, Tsuyoshi*; Koizumi, Yoshiharu*; Kamiya, Tomihiro; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.173 - 176, 2004/10
no abstracts in English
Hirao, Toshio; Laird, J. S.; Onoda, Shinobu; Wakasa, Takeshi; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.187 - 189, 2004/10
no abstracts in English
Wakasa, Takeshi; Hirao, Toshio; Sanami, Toshiya*; Onoda, Shinobu; Abe, Hiroshi; Tanaka, Susumu; Kamiya, Tomihiro; Okamoto, Tsuyoshi*; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.213 - 216, 2004/10
no abstracts in English
Oshima, Takeshi; Lee, K. K.; Onoda, Shinobu*; Kamiya, Tomihiro; Oikawa, Masakazu*; Laird, J. S.; Hirao, Toshio; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 210, p.201 - 205, 2003/09
Times Cited Count：4 Percentile：33.69(Instruments & Instrumentation)Electrodes on SiC pn diode were studied uising Transient Ion Beam Induced Current system (TIBIC). pn junction of SiC diode was formed by phosphorus ion implantation at 800 
C and subsequent annealing at 1800 C for 1 min in Ar. Electrodes of diode were fabricated (1) Al evaporation and sintering at 850 C or (2) one more Al evaporation after the process mentioned above. TIBIC measurement using 15 MeV-O and 12 MeV-Ni ion micro beam. As the result, non-uniformity for transient current from the electrodes of diode (1)was observed. As for diode (2), such non-uniformity was not observed. On the other hand, the value of collected charges was the same for both diodes. This indicates that the quality of pn junction is the almost same for both diodes. For current-voltage characteristics, both diodes showed a order of pA at reverse bias of 30 V and turn-on at forward bias of 2V which are ideal for SiC diode. Thus, we can conclude that we obtain the information on electrical characteristics of electrodes which is not obtained from normal current-voltage measurement.
Lee, K. K.; Oshima, Takeshi; Saint, A.*; Kamiya, Tomihiro; Jamieson, D. N.*; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 210, p.489 - 494, 2003/09
Times Cited Count：21 Percentile：78.49(Instruments & Instrumentation)To obtain the information on radiation damage of 6H-SiC devices, ion beam induced charge collection (IBICC) for 6H-SiC schottky diodes irradiated with proton, alpha and carbon micro beam 10
to 10
ions/cm
was studied. No significant difference of degradation was observed between p- and n-substrates irradiated with 2MeV-alpha micro beam. The decrease in IBCC shows a good agreement with the calculation using non ionizing energy loss (NIEL). As a result of ion luminescence and ultra violet photo luminescence, the level of 2.32 eV was observed.
Nishijima, Toshiji*; Hearne, S. M.*; Jamieson, D. N.*; Oshima, Takeshi; Lee, K. K.; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 210, p.196 - 200, 2003/09
Times Cited Count：1 Percentile：12.51(Instruments & Instrumentation)The radiation damage in silicon carbide (SiC) schottky diode was studied using ion beam induced current (IBIC). Schottky diodes with electrodes of 30 m on n- or p-type 6H-SiC were fabricated using the evaporation of Al, Ni, and Au. To study the radiation damage of diodes, the 2MeV-He ion micro beam with a diameter of 1 m was irradiated from 10
to 10/cm into a 10 m 
10 m area. As the result, the value of IBIC decreased with increasing the dose of 2 MeV-He. This indicates that the charge collection decreases by the recombination centers introduced by irradiation.
Kamiya, Tomihiro; Oikawa, Masakazu*; Oshima, Takeshi; Hirao, Toshio; Lee, K. K.; Onoda, Shinobu*; Laird, J. S.
Nuclear Instruments and Methods in Physics Research B, 210, p.206 - 210, 2003/09
Times Cited Count：1 Percentile：12.51(Instruments & Instrumentation)no abstracts in English
Oshima, Takeshi; Lee, K. K.; Onoda, Shinobu; Kamiya, Tomihiro; Oikawa, Masakazu*; Laird, J. S.; Hirao, Toshio; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.979 - 983, 2003/05
Times Cited Count：8 Percentile：50.24(Instruments & Instrumentation)Ion beam induced current for pn SiC diode was observed by using MeV range ion beams.The diodes used in this study were pn diode fabricated on n-type epitaxial 6H-SiC. The p region was formed using Al-ion implantation at 800 C and subsequent annealing at 1800 C. The value of charge collection for diode applied to 30V by 12MeV-Ni microbeam irradiationis estimated to be (1.7-1.8)10
Q from the analyzing transient-IBIC measurement.The efficiency of the charge collection is 85-93%.
Mori, Hidenobu; Hirao, Toshio; Laird, J. S.; Onoda, Shinobu; Ito, Hisayoshi
JAERI-Review 2002-035, TIARA Annual Report 2001, p.14 - 16, 2002/11
no abstracts in English
Nishijima, Toshiji*; Oshima, Takeshi; Lee, K. K.
Nuclear Instruments and Methods in Physics Research B, 190(1-4), p.329 - 334, 2002/05
Times Cited Count：11 Percentile：58.11(Instruments & Instrumentation)no abstracts in English
