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Matsuoka, Moe*; Nakamura, Tomoki*; Osawa, Takahito; Iwata, Takahiro*; Kitazato, Kohei*; Abe, Masanao*; Nakauchi, Yusuke*; Arai, Takehiko*; Komatsu, Mutsumi*; Hiroi, Takahiro*; et al.
Earth, Planets and Space (Internet), 69(1), p.120_1 - 120_12, 2017/12
Times Cited Count：6 Percentile：21.84(Geosciences, Multidisciplinary)We have conducted ground-based performance evaluation tests of the Near-Infrared Spectrometer (NIRS3) onboard Hayabusa2 spacecraft and established a method for evaluating its measured reflectance spectra. Reflectance spectra of nine powdered carbonaceous chondrite samples were measured by both NIRS3 and a FT-IR spectrometer. Since raw data obtained by NIRS3 had considerable spectral distortion caused by systematic offsets in sensitivity of individual pixels, we have established two methods for correcting the NIRS3 data by comparing them with the corresponding FT-IR data. In order to characterize the absorption bands in NIRS3 spectra, the depth of each band component D
is defined for each wavelength (
m). Reflectance spectra of asteroid Ryugu, the target asteroid of Hayabusa2, to be recorded by the NIRS3 are expected to reveal the characteristics of the surface materials by using the evaluation technique.
Takahashi, Hiroki; Narita, Takahiro; Usami, Hiroki; Sakaki, Hironao; Kojima, Toshiyuki*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.756 - 759, 2015/09
no abstracts in English
Kada, Wataru*; Kambayashi, Yuya*; Iwamoto, Naoya*; Onoda, Shinobu; Makino, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Hoshino, Norihiro*; Tsuchida, Hidekazu*; Kojima, Kazutoshi*; et al.
Nuclear Instruments and Methods in Physics Research B, 348, p.240 - 245, 2015/04
Times Cited Count：4 Percentile：33.25(Instruments & Instrumentation)Takahashi, Hiroki; Maebara, Sunao; Kojima, Toshiyuki; Narita, Takahiro; Tsutsumi, Kazuyoshi; Sakaki, Hironao; Suzuki, Hiromitsu; Sugimoto, Masayoshi
Fusion Engineering and Design, 89(9-10), p.2066 - 2070, 2014/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Takahashi, Hiroki; Narita, Takahiro; Nishiyama, Koichi; Usami, Hiroki; Sakaki, Hironao; Kasugai, Atsushi; Kojima, Toshiyuki*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.799 - 802, 2014/10
no abstracts in English
Takahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Maebara, Sunao; Sakaki, Hironao; Suzuki, Hiromitsu
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.724 - 727, 2014/06
no abstracts in English
Deki, Manato*; Makino, Takahiro; Kojima, Kazutoshi*; Tomita, Takuro*; Oshima, Takeshi
Materials Science Forum, 778-780, p.440 - 443, 2014/02
Times Cited Count：3 Percentile：82.26(Crystallography)no abstracts in English
-ray and neutron area monitoring system of linear IFMIF prototype accelerator buildingTakahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Tsutsumi, Kazuyoshi; Maebara, Sunao; Sakaki, Hironao; Nishiyama, Koichi
Fusion Engineering and Design, 88(9-10), p.2736 - 2739, 2013/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)For radiation safety of the Linear IFMIF Prototype Accelerator, -ray and neutron area monitoring system are designed. This system monitors and records the measured data by using both a supervisory board in the access room and central control system. The interlock signals are sent to Personnel Protection System (PPS) and Machine Protection System (MPS) when the integrated dose value exceeds a threshold value. After receiving them, the PPS and the MPS immediately inhibit the beam operation for secure radiation safety. This monitoring system is designed to achieve a high reliability for data transfer using hardwired interlock signals and the performance of data communication between area monitoring system and control system.
Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Nozaki, Shinji*
Proceedings of SPIE, Vol.8725 (CD-ROM), 8 Pages, 2013/06
Times Cited Count：0 Percentile：0.01(Nanoscience & Nanotechnology)Oshima, Takeshi; Deki, Manato; Makino, Takahiro; Iwamoto, Naoya; Onoda, Shinobu; Hirao, Toshio*; Kojima, Kazutoshi*; Tomita, Takuro*; Matsuo, Shigeki*; Hashimoto, Shuichi*
AIP Conference Proceedings 1525, p.654 - 658, 2013/04
Times Cited Count：0 Percentile：0.05(Physics, Applied)Metal-Oxide-Semiconductor (MOS) capacitors were fabricated on n-type 4H-SiC epitaxial layers, and the leakage current through the gate oxide during heavy ion irradiation was investigated in order to evaluate dielectric breakdown induced by heavy ions (Single Event Gate Rupture: SEGR). The gate oxide at thickness ranges between 60 and 80 nm was formed using pyrogenic oxidation at 1100 
C for 60 min. Circular electrodes with 180 diameter were formed using Al evaporation and a lift-off technique. The leakage current observed through the gate oxide was monitored during 18 MeV oxygen (O) or nickel (Ni) ions. As a result, although no significant difference in the value of the electric field at the dielectric breakdown (around 8.2 MV/cm) was observed between non-irradiated and 18 MeV-O irradiated samples, the value decreased to be 7.3 MV/cm in the case of 18 MeV-Ni ion incidence. The Linier Energy Transfer (LET) for 18 MeV-O is 7 MeV cm
/mg, and this value is smaller than that for 18 MeV-Ni (24 MeV cm/mg). Also, 18 MeV-Ni ions deposit energy in narrower regions than 18 MeV-O ions. Thus, it can be concluded that the high density of charge induced by 18 MeV-Ni ions triggers SEGR in SiC MOS capacitors.
Deki, Manato; Makino, Takahiro; Tomita, Takuro*; Hashimoto, Shuichi*; Kojima, Kazutoshi*; Oshima, Takeshi
Proceedings of 10th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-10) (Internet), p.78 - 81, 2012/12
Metal-Oxide-Semiconductor (MOS) capacitors fabricated on Silicon Carbide (SiC) under applied biases were irradiated with heavy ions. The relationship between critical electric field (E
) and Linear Energy Transfer (LET) was investigated. As a results of 9 MeV-Ni, 18 MeV-Ni, Kr-322 MeV and 454 MeV-Xeirradiation (the values of LET are 14.6, 23.8, 42.2 and 73.2 MeV cm/mg, respectively), reciprocal value of E increases with increasing LET. The similar relationship was also reported Si MOS capacitors. However, the increase in SiC MOS capacitors is smaller than that in Si ones because the generation energy of one electron-hole pair for SiC is larger than that for Si.
Takahashi, Hiroki; Kojima, Toshiyuki; Narita, Takahiro; Sakaki, Hironao; Komukai, Satoshi*
Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3972 - 3974, 2012/07
Control System for LIPAc realizes the remote control and monitoring and data acquisition by use of EPICS. For the validations of each subsystem performance and the activity of IFMIF Accelerator design, it is very important data obtained by commissioning of LIPAc and each subsystem. To certainly archive the important data for LIPAc and to efficiently search the LIPAc data, for design and validation, we started developing Data Acquisition System (DAC) based on Relational Database (RDB) has been developed. The first design for DAC of LIPAc is configured (1) using PostgreSQL for RDB and (2) several RDB for data archiving to ensure the data archive performance and to consider the increasing data amount. In addition, (3) only one RDB for data search is included in DAC and users can search the data via this RDB. In this way, several RDB for DAC can behave only one RDB against users. In this article, the development status of DAC for LIPAc is presented.
Makino, Takahiro; Iwamoto, Naoya*; Onoda, Shinobu; Oshima, Takeshi; Kojima, Kazutoshi*; Nozaki, Shinji*
Materials Science Forum, 717-720, p.469 - 472, 2012/05
Times Cited Count：1 Percentile：54.7(Materials Science, Multidisciplinary)The peak amplitude of ion induced transient current in n-type 6H-SiC MOS capacitors decreased as the number of incident ions increased and the decrease was recovered to the initial value by applying a positive bias at +1 V. In addition, we monitored a change in the capacitance for the MOS capacitors during ion irradiation. The capacitances increase as the number of incident ion increase. Thus, the result obtained in this study indicates that the depletion layer decreased as the increasing number of incident ions and saturated. Since the number of incident ions at the peak current saturation corresponds to the saturation of the capacitance, we can conclude that the decrease in peak current comes from the decrease in the depletion layer. In addition, the generation of electron-hole pairs by incident ion may result in the formation of an inversion layer. This would have the effect of shielding the charge carriers from the applied bias further reducing the depletion layer width.
Iwamoto, Naoya*; Koizumi, Atsushi*; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Koike, Shumpei*; Uchida, Kazuo*; Nozaki, Shinji*
Materials Science Forum, 717-720, p.267 - 270, 2012/05
Times Cited Count：1 Percentile：54.7(Materials Science, Multidisciplinary)In this study, we carried out an attempt to identify the defects responsible for the degraded charge collection efficiency of the 6H-SiC p
n diode irradiated with 1 MeV electrons by the alpha particle induced charge transient spectroscopy. To form defects in the SiC crystal, one of the diodes was irradiated with 1 MeV electrons at a fluence of 1
10
/cm. Collected charges of the diodes were measured in room temperature using 5.486 MeV alpha particles from 
Am source. After the electron irradiation, the collected charge of the diode at a reverse bias of 100 V decreased to 84% of its initial value. In order to investigate the relationship between degradation of collected charge and defects in detail, time-dependent collected charges of the diodes were measured in temperature ranges from 170 K to 310 K. As a result, two distinct peaks labeled X
and X
are found for the electron-irradiated diode, and their activation energies are estimated to be 0.30 and 0.47 eV, respectively. These two peaks are considered to correspond to the defect levels introduced by the electron irradiation. In particular, when the diodes are used in room temperature, X is more critical to the charge collection than X.
Komatsu, Hisanori*; Kojima, Kentaro*; Funato, Yoshiki*; Matsuda, Yasuhiro*; Kijimura, Taiki*; Okuyama, Katsushi*; Yamamoto, Hiroko*; Iwami, Yukiteru*; Ebisu, Shigeyuki*; Nomachi, Masaharu*; et al.
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 85, 2012/01
n diode irradiated with high-energy electronsIwamoto, 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
Times Cited Count：5 Percentile：38.65(Engineering, Electrical & Electronic)no abstracts in English
Takahashi, Hiroki; Kojima, Toshiyuki; Tsutsumi, Kazuyoshi; Narita, Takahiro; Nishiyama, Koichi; Sakaki, Hironao; Maebara, Sunao
Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.1734 - 1736, 2011/09
Control system for the IFMIF/EVEDA prototype accelerator consists of six subsystems; Central Control System (CCS), Local Area Network (LAN), Personnel Protection System (PPS), Machine Protection System (MPS), Timing System (TS) and Local Control System (LCS). The Prototype Accelerator provides the deuteron beam with the beam power more than 1 MW, and this control system is required the high reliability and usability to perform various operation modes for beam commissioning. To satisfy these requirements, we are developing mainly PPS, MPS and TS at the beginning. This paper presents the status of hardware development of the PPS, MPS and TS.
-raysOshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Nozaki, Shinji*; Kojima, Kazutoshi*
Materials Science Forum, 679-680, p.362 - 365, 2011/03
Times Cited Count：1 Percentile：57.27(Engineering, Multidisciplinary)Charge induced in the 6H-Silicon Carbide (SiC) n Metal-Oxide-Semiconductor (MOS) capacitors by 15 MeV oxygen ion microbeams was evaluated using Transient Ion Beam Induced Current (TIBIC) before and after -ray irradiations. With increasing number of incident ions, the peak height of TIBIC signals decreases and the fall time increases. The decrease in TIBIC peak finally saturated. The peak height of the TIBIC signal can be refreshed to its original shape by applying a positive bias of + 1V to the oxide electrode. This result can be explained in terms of the existence of deep hole traps. Small decrease in both TIBIC signal peak and collected charge was observed due to -ray irradiation.
Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Koizumi, Atsushi*; Uchida, Kazuo*; Nozaki, Shinji*
IEEE Transactions on Nuclear Science, 58(1), p.305 - 313, 2011/02
Times Cited Count：10 Percentile：60.88(Engineering, Electrical & Electronic)no abstracts in English
Onoda, Shinobu; Makino, Takahiro; Iwamoto, Naoya*; Vizkelethy, G.*; Kojima, Kazutoshi*; Nozaki, Shinji*; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 57(6), p.3373 - 3379, 2010/12
no abstracts in English
