Takai, Shizuka; Namekawa, Masakazu*; Shimada, Taro; Takeda, Seiji
IEEE Transactions on Nuclear Science, 69(7), p.1789 - 1798, 2022/07
To reduce a large amount of contaminated concrete rubble stored in the Fukushima Daiichi Nuclear Power Station site, recycling low-radioactivity rubble within the site is a possible remedy. To promote recycling while ensuring safety, not only the average radioactivity but also the radioactivity distribution of concrete rubble should be efficiently evaluated because the details of rubble contamination caused by the accident remain unclear and likely include hotspots. However, evaluating inhomogeneous contamination of thick and/or dense materials is difficult using previous measurement systems, such as clearance monitors. This study experimentally confirmed the potential applicability of image reconstruction algorithms for radioactivity distribution evaluation in concrete rubble filled in a chamber. Radiation was measured using plastic scintillation fiber around the chamber (50 50 40 cm). Localized hotspots were simulated using standard sources of Cs, which is one of the main nuclides of contaminated rubble. The radioactivity distribution was calculated for 100 or 50 voxels (voxel size: (10 cm) or 10 10 20 cm) constituting the chamber. For 100 voxels, inner hotspots were undetected, whereas, for 50 voxels, both inner and surface hotspots were reconstructible. The distribution evaluated using the maximum likelihood expectation maximization algorithm was the most accurate; the average radioactivity was estimated within 70% accuracy in all seven cases.
Tamura, Fumihiko; Takahashi, Hiroki; Kamikubota, Norihiko*; Ito, Yuichi*; Hayashi, Naoki
IEEE Transactions on Nuclear Science, 68(8), p.2043 - 2050, 2021/08
A precise and stable timing system is necessary for high intensity proton accelerators such as the J-PARC. The existing timing system, which was developed during the construction period of the-PARC, has been working without major issues since 2006. After a decade of operation, the optical modules, which are key components for signal transfer, were discontinued already. Thus, the next-generation timing system for the J-PARC is under development. The new system is designed to be compatible with the existing system in terms of the operating principle. The new system utilizes modern high speed signal communication for the transfer of the clock, trigger, and type code. We present the system configuration of the next-generation timing system and current status.
Liao, W.*; Ito, Kojiro*; Abe, Shinichiro; Mitsuyama, Yukio*; Hashimoto, Masanori*
IEEE Transactions on Nuclear Science, 68(6), p.1228 - 1234, 2021/06
Secondary cosmic-ray neutron-induced single event upset (SEU) is a cause of soft errors on micro electronic devices. Multiple cell upsets (MCUs) are particularly serious problems since it is difficult to recover MCUs. In this study, we have performed irradiation tests of neutrons on 65-nm bulk SRAM at the national metrology institute of Japan (NMIJ) in Advanced Industrial Science and Technology (AIST) and measured SEU cross sections and MCU cross sections to investigate the effect on neutrons with the energies below 10 MeV on soft errors. It was found that SEU cross sections change drastically around 6 MeV. The proportion of MCU to total events does not change very much over the wide range of neutron energy. We also analyzed the total soft error rate (SER) of SEU and MCU by folding the neutron energy-dependent cross section and the flux spectra of the terrestrial neutron at New York and Tokyo. The calculated result indicates that the SER originating from the low-energy neutrons below 10 MeV is mostly negligible in the terrestrial environment.
Morishita, Yuki; Izaki, Kenji; Kaneko, Junichi*; Yamamoto, Seiichi*; Higuchi, Mikio*; Torii, Tatsuo
IEEE Transactions on Nuclear Science, 67(10), p.2203 - 2208, 2020/10
We developed a GdSiO (GPS) scintillator-based alpha imaging detector and demonstrated its effectiveness by evaluating actual Pu particle and Rn progeny. The GPS scintillator plate was prepared by a sintering method. The outer dimensions of the GPS scintillator plate were 5 5 cm, and the scintillator layer was approximately 50 m on a 3-mm-thick high-transparency glass. The plate was optically coupled to a position-sensitive photomultiplier tube with silicone grease. The developed imaging detector exhibited good uniformity. Pu particle activities were accurately evaluated at 14 different positions, and the difference in activity was within 6%. Radon-222 (Rn) progeny counts were reduced by 65.3% by applying an energy window. Although the Pu/Rn progeny activity ratio was 1/51, the Pu particle was successfully identified among Rn progeny within the 5 min-measurement time. The imaging detector has an excellent ability for detecting Pu among Rn progeny. Thus, this detector is useful for alpha contamination monitoring in high-radon-background environments.
Abe, Shinichiro; Liao, W.*; Manabe, Seiya*; Sato, Tatsuhiko; Hashimoto, Masanori*; Watanabe, Yukinobu*
IEEE Transactions on Nuclear Science, 66(7, Part2), p.1374 - 1380, 2019/07
Single event upsets (SEUs) caused by secondary cosmic-ray neutrons have recognized as a serious reliability problem for microelectronic devices. Acceleration tests at neutron facilities are convenient to validate soft error rates (SERs) quickly, but some corrections caused from measurement conditions are required to derive realistic SERs at actual environment or to compare other measured data. In this study, the effect of irradiation side on neutron-induced SEU cross sections was investigated by performing neutron transport simulation using PHITS. SERs for 65-nm bulk CMOS SRAMs are estimated using the sensitive volume model. It was found from simulation that SERs for the sealant side irradiation are 30-50% larger than those for the board side irradiation. This difference comes from the difference of production yield and angular distribution of secondary H and He ions, which are the main cause of SEUs. Thus the direction of neutron irradiation should be reported when the result of acceleration tests are published. This result also indicates that SERs can be reduced by equipping device with sealant side facing downward.
Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Ryoshi, Masatsugu*
IEEE Transactions on Nuclear Science, 66(7), p.1242 - 1248, 2019/07
The LLRF control system for the rapid cycling synchrotron of the J-PARC started its operation in 2007. The key functions of the LLRF control system are the dual harmonic auto voltage control and the multiharmonic rf feedforward to compensate the beam loading in the MA cavity caused by high intensity beams. The system has been working well without major problems for more than ten years. However, the old FPGAs are discontinued and not supported by the current development environment. It will be difficult to maintain the system in near future. Thus, we are planning to replace the existing VME-based LLRF control system with a new MicroTCA.4 based system. In this presentation, we present the configuration of the system under development, the implemented functions, and preliminary test results.
Nancekievill, M.*; Jones, A. R.*; Joyce, M. J.*; Lennox, B.*; Watson, S.*; Katakura, Junichi*; Okumura, Keisuke; Kamada, So*; Kato, Michio*; Nishimura, Kazuya*
IEEE Transactions on Nuclear Science, 65(9), p.2565 - 2572, 2018/09
In order to contribute to the development of technology to search fuel debris submerged in water inside the primary containment vessel of the Fukushima Daiichi Nuclear Power Station, we are developing a remotely operated vehicle (ROV) system equipped with a compact radiation detector and sonar. A cerium bromide (CeBr) scintillator detector for dose rate monitoring and ray spectroscopy was integrated into ROV and experimentally validated with a Cs source, both in the conditions of laboratory and submerged. In addition, the ROV combined with the IMAGENEX 831L sonar could characterize the shape and size of a simulated fuel debris at the bottom of the water pool facility.
Manabe, Seiya*; Watanabe, Yukinobu*; Liao, W.*; Hashimoto, Masanori*; Nakano, Keita*; Sato, Hikaru*; Kin, Tadahiro*; Abe, Shinichiro; Hamada, Koji*; Tampo, Motonobu*; et al.
IEEE Transactions on Nuclear Science, 65(8), p.1742 - 1749, 2018/08
Recently, the malfunction of microelectronics caused by secondary cosmic-ray muon is concerned as semiconductor devices become sensitive to radiation. In this study, we have performed muon irradiation testing for 65-nm ultra-thin body and thin buried oxide (UTBB-SOI) SRAMs in the Japan Proton Accelerator Research Complex (J-PARC), in order to investigate dependencies of single event upset (SEU) cross section on incident muon momentum and supply voltage. It was found that the SEU cross section by negative muon are approximately two to four times larger than those by positive muon in the momentum range from 35 MeV/c to 39 MeV/c. The supply voltage dependence of muon-induced SEU cross section was measured with the momentum of 38 MeV/c. SEU cross sections decrease with increasing supply voltage, but the decreasing of SEU cross section by negative muon is gentler than that by positive muon. Experimental data of positive and negative muon irradiation with the momentum of 38 MeV/c were analyzed by PHITS. It was clarified that the negative muon capture causes the difference between the SEU cross section by negative muon and that by positive muon.
Liao, W.*; Hashimoto, Masanori*; Manabe, Seiya*; Watanabe, Yukinobu*; Abe, Shinichiro; Nakano, Keita*; Sato, Hikaru*; Kin, Tadahiro*; Hamada, Koji*; Tampo, Motonobu*; et al.
IEEE Transactions on Nuclear Science, 65(8), p.1734 - 1741, 2018/08
Soft error induced by secondary cosmic-ray muon is concerned since susceptibility of semiconductor device to soft error increases with the scaling of technology. In this study, we have performed irradiation tests of muons on 65-nm bulk CMOS SRAM in the Japan Proton Accelerator Research Complex (J-PARC) and measured soft error rate (SER) to investigate mechanism of muon-induced soft errors. It was found that SER by negative muon increases above 0.5 V supply voltage, although SER by positive muon increases monotonically as the supply voltage lowers. SER by negative muon also increases with forward body bias. In addition, negative muon causes large multiple cell upset (MCU) of more than 20 bits and the ratio of MCU events to all the events is 66% at 1.2V supply voltage. These tendencies indicate that parasitic bipolar action (PBA) is highly possible to contribute to SER by negative muon. Experimental data are analyzed by PHITS. It was found that negative muon can deposit larger charge than positive muon, and such events that can deposit large charge may trigger PBA.
Takeuchi, Tomoaki; Shibata, Hiroshi; Otsuka, Noriaki; Uehara, Toshiaki; Tsuchiya, Kunihiko; Shibagaki, Taro*; Komanome, Hirohisa*
IEEE Transactions on Nuclear Science, 63(5), p.2698 - 2702, 2016/10
In response to the lesson of the accident at the Fukushima Dai-ichi Nuclear Power Plant, we started a development of a radiation-resistant in-water wireless transmission system. In this study, capability of light emitting diodes (LED) and photo diodes (PD) as light emitting and receiving devices was researched. Results of irradiation tests of LEDs and PDs up to 1 MGy indicated a main cause of the degradation of the optical performances of the diodes was not the radiation damage at the semiconductor parts but the coloring of the resin parts. Assuming that the use of the candidate LED and PD, the PD's output current generated by the emission light of the LED at five meters away in water was estimated to be detectable intensity even considering the effects of the absorption of the light by water and the increased dark current by 1 MGy irradiation. Therefore, a radiation resistant in-water transmission system can be constructed using LEDs and PDs in principle.
Mizuta, Eiichi*; Kuboyama, Satoshi*; Abe, Hiroshi; Iwata, Yoshiyuki*; Tamura, Takashi*
IEEE Transactions on Nuclear Science, 61(4), p.1924 - 1928, 2014/08
Onoda, Shinobu; Hasuike, Atsushi*; Nabeshima, Yoshiaki*; Sasaki, Hajime*; Yajima, Kotaro*; Sato, Shinichiro; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 60(6), p.4446 - 4450, 2013/12
no abstracts in English
Makino, Takahiro; Deki, Manato; Iwamoto, Naoya; Onoda, Shinobu; Hoshino, Norihiro*; Tsuchida, Hidekazu*; Hirao, Toshio*; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 60(4), p.2647 - 2650, 2013/08
Heavy ion induced anomalous charge collection was observed from 4H-SiC Schottky barrier diodes. It is suggested that the incident ion range with suspect to the thickness of the epi-layer of the SBD in key to understanding these observation and the understanding mechanism.
Sato, Shinichiro; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 60(3), p.2288 - 2299, 2013/06
Electric conductivity variations of hydrogenated amorphous silicon due to self-ion irradiation are comprehensively investigated. The anomalous enhancement of dark conductivity (DC) and photoconductivity (PC) are firstly observed due to proton irradiation, and after that both decrease with increasing the irradiation fluence. The decrease in DC and PC is ascribed to the carrier removal effect and the carrier lifetime decrease accompanied by accumulation of dangling bonds, respectively. However, further irradiation causes the loss of photoconduction and the drastic increase in DC. This indicates that the dominant conduction mechanism changes from the band transport to the hopping transport due to excessive accumulation of dangling bonds. It is concluded that the conductivity variations caused by self-ion irradiation can be systematically categorized according to the ratio of the nuclear energy deposition to the electronic energy deposition of incident ions.
Makihara, Akiko*; Yokose, Tamotsu*; Tsuchiya, Yoshihisa*; Miyazaki, Yoshio*; Abe, Hiroshi; Shindo, Hiroyuki*; Ebihara, Tsukasa*; Maru, Akifumi*; Morikawa, Koichi*; Kuboyama, Satoshi*; et al.
IEEE Transactions on Nuclear Science, 60(1), p.230 - 235, 2013/02
no abstracts in English
Onoda, Shinobu; Makino, Takahiro; Ono, Shuichi*; Katakami, Shuji*; Arai, Manabu*; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 59(4), p.742 - 748, 2012/08
no abstracts in English
Masuda, Akihiko*; Matsumoto, Tetsuro*; Harano, Hideki*; Nishiyama, Jun*; Iwamoto, Yosuke; Hagiwara, Masayuki*; Satoh, Daiki; Iwase, Hiroshi*; Yashima, Hiroshi*; Nakamura, Takashi*; et al.
IEEE Transactions on Nuclear Science, 59(1), p.161 - 166, 2012/02
In this study, responses of Bonner sphere spectrometer (BSS) for 245 and 388 MeV neutrons was measured at RCNP, Osaka University. The neutrons are generated in the Li(p,n) reaction and its spectra consist of a high-energy peak and a continuum down to the low energy. Therefore, the observed counts of BSS caused by the continuum need to be subtracted. Adjusting a Li target angle and a collimator position, 0 deg and 30 deg component of generated neutron are available. While the 0 deg component contains both the peak and the continuum, the 30 deg component is considered to contain only the continuum. Therefore, the response of the peak is obtained. The spectra were measured using the time-of-flight (TOF) method with a NE213 scintillator.
Iwamoto, Naoya; Koizumi, Atsushi*; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Koike, Shumpei*; Uchida, Kazuo*; Nozaki, Shinji*
IEEE Transactions on Nuclear Science, 58(6), p.3328 - 3332, 2011/12
no abstracts in English
Inaba, Yoshitomo; Iimura, Koichi; Hosokawa, Jinsaku; Izumo, Hironobu; Hori, Naohiko; Ishitsuka, Etsuo
IEEE Transactions on Nuclear Science, 58(3), p.1151 - 1158, 2011/06
The Japan Materials Testing Reactor (JMTR) is now under refurbishment, and the operation of the new JMTR will start in FY 2011. The new JMTR has a plan to produce Mo, which is the parent nuclide of Tc, and two Mo production technologies have been developed: one is a solid irradiation method, and the other is a solution irradiation method. In this paper, the present status of the development on the Mo production technologies with the solid and solution irradiation methods was described. In the solid irradiation method, it was found that JMTR can provide about 20% of the Mo imported into Japan. In the solution irradiation method, the fundamental characteristics of the aqueous molybdate solutions selected as candidates for the irradiation target were cleared by the -ray irradiation test.
Kawachi, Naoki; Kikuchi, Kaori*; Suzui, Nobuo; Ishii, Satomi; Fujimaki, Shu; Ishioka, Noriko; Watabe, Hiroshi*
IEEE Transactions on Nuclear Science, 58(2), p.395 - 399, 2011/04