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Kimura, Yoshiki; Tsuchiya, Kenichi*
Radioisotopes, 72(2), p.121 - 139, 2023/07
Rapid and precise radioisotope identification in the scene of nuclear detection and nuclear security incidents is one of the challenging issues for the prompt response on the detection alarm or the incidents. A radioisotope identification algorithm using a deep artificial neural network model applicable to handheld gamma-ray detectors has been proposed in the present paper. The proposed algorithm automatically identifies gamma-emitting radioisotopes based on the count contribution ratio (CCR) from each of them estimated by the deep artificial neural network model trained by simulated gamma-ray spectra. The automated radioisotope identification algorithm can support first responders of nuclear detection and nuclear security incidents without sufficient experience and knowledge in radiation measurement. The authors tested the performance of the proposed algorithm using two different types of deep artificial neural network models in application to handheld detectors having high or low energy resolution. The proposed algorithm showed high performance in identifying artificial radioisotopes for actually measured gamma-ray spectra. It was also confirmed that the algorithm is applicable to identifying 
U and automated uranium categorization by analyzing estimated CCRs by the deep artificial neural network models. The authors also com-pared the performance of the proposed algorithm with a conventional radioisotope identification method and discussed promising ways to improve the performance of the algorithm using the deep artificial neural network.
Mochimaru, Takanori*; Koizumi, Mitsuo; Takahashi, Tone; Hironaka, Kota; Kimura, Yoshiki; Sato, Yuki; Terasaka, Yuta; Yamanishi, Hirokuni*; Wakabayashi, Genichiro*
Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11
no abstracts in English
Kimura, Yoshiki; Matsui, Yoshiki; Tomikawa, Hirofumi
ITWG Nuclear Forensics Update (Internet), (15), p.4 - 7, 2020/06
Tamai, Hiroshi; Okubo, Ayako; Kimura, Yoshiki; Shinohara, Nobuo; Tazaki, Makiko; Shimizu, Ryo; Suda, Kazunori; Tomikawa, Hirofumi
Proceedings of INMM 58th Annual Meeting (Internet), 6 Pages, 2017/07
Nuclear forensics is a technical measure to analyse and collate samples of illegally used nuclear materials, etc., to clarify their origins, routes, etc. and contribute to criminal identifications. Close collaboration with police and judicial organizations is essential. The national response framework is being built up with international cooperation. Discussions on promoting technical capability and regional cooperation are presented.
Tamai, Hiroshi; Okubo, Ayako; Kimura, Yoshiki; Kokaji, Lisa; Shinohara, Nobuo; Tomikawa, Hirofumi
Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu (CD-ROM), 8 Pages, 2017/02
Nuclear Forensics capability has been developed under the international collaborations. For its effective function, technical development in analysis of seized nuclear materials as well as the institutional development in comprehensive response framework are required under individual national responsibility. In order to keep the "chain of custody" in the proper operation of sample collection at the event scene, radiological analysis at the laboratory, storage of the samples, and further inspection and trial, close cooperation and information sharing between relevant organisations are essential. IAEA issues the Implementing Guide to provide the model action plan and assists individual national development. International cooperation for the technical improvement and awareness cultivation is promoted. Examples in such national developments will be introduced and prospective technical/institutional prerequisite for nuclear forensics response framework will be studied.
Kimura, Yoshiki; Shinohara, Nobuo; Okubo, Ayako
Nihon Genshiryoku Gakkai-Shi ATOMO
, 57(12), p.782 - 786, 2015/12
no abstracts in English
Kimura, Yoshiki; Shinohara, Nobuo; Funatake, Yoshio
Proceedings of INMM 56th Annual Meeting (Internet), 8 Pages, 2015/07
Okubo, Ayako; Kimura, Yoshiki; Shinohara, Nobuo; Toda, Nobufumi; Funatake, Yoshio; Watahiki, Masaru; Sakurai, Satoshi; Kuno, Yusuke
JAEA-Technology 2015-001, 185 Pages, 2015/03
JAEA-Technology-2015-001.pdf:56.65MB
Nuclear forensics is the analysis of intercepted illicit nuclear or radioactive material and any associated material to provide evidence for nuclear attribution by determining origin, history, transit routes and purpose involving such material. Nuclear forensics activity includes sampling of the illicit material, analysis of the samples and evaluation of the attribution by comparing the analyzed data with database or numerical simulation. Because the nuclear forensics technologies specify the origin of the nuclear materials used illegal dealings or nuclear terrorism, it becomes possible to identify and indict offenders, hence to enhance deterrent effect against such terrorism. Worldwide network on nuclear forensics can contribute to strengthen global nuclear security regime. In this paper, the results of research and development of fundamental nuclear forensics technologies performed in Japan Atomic Energy Agency during the fiscal term of 2011-2013 were reported.
Kimura, Yoshiki; Shinohara, Nobuo; Sato, Kaneaki; Toda, Nobufumi; Shinoda, Yoshiharu; Funatake, Yoshio; Watahiki, Masaru; Kuno, Yusuke
Proceedings of INMM 55th Annual Meeting (Internet), 7 Pages, 2014/07
In 2010, the Japan Government issued the national statement at Nuclear Security Summit (Washington D.C., USA) to develop technologies related to measurement and detection of nuclear materials for nuclear forensics within three-year timeframe, and to share the products with the international community in order to contribute to strengthening the nuclear security system. In response to this statement, JAEA that possesses sufficient technical capabilities to fulfil this nuclear forensics mission has started a nuclear forensics technology development project since JFY 2011. This paper will present the progress of the development project during JFY 2011 to 2013. This project includes the developments of analytical technologies such as isotope and impurity measurements, morphology analysis, age determination technique, and the prototype of national nuclear forensics library (NNFL). Some future prospects of this project will be also presented in this paper.
Kimura, Yoshiki; Shinohara, Nobuo; Funatake, Yoshio
Journal of Nuclear Materials Management, 42(4), p.40 - 45, 2014/00
Japan Atomic Energy Agency (JAEA) has initiated an R&D project on nuclear forensics technology from 2011. This project includes development of prototype national nuclear forensics library (NNFL), and the JAEA attended to the first international table top exercise of NNFL "Galaxy Serpent" held by ITWG as a part of our NNFL development project. In this paper, outline and experiences of the JAEA investigation in the table top exercise are described and the lessons learned from the experiences were discussed. Brief current status of the NNFL development project at JAEA was also introduced in the present paper. The lessons from the experiences in the exercise will be effectively applied to the development of NNFL at JAEA.
Kimura, Yoshiki; Shinohara, Nobuo; Funatake, Yoshio; Sato, Kaneaki; Toda, Nobufumi; Shinoda, Yoshiharu; Watahiki, Masaru; Kuno, Yusuke
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10
Japan Atomic Energy Agency (JAEA) has initiated R&D project on nuclear forensics technology such as analytical technologies towards the establishment of nuclear forensics capabilities in Japan. National Nuclear Forensics Library (NNFL) is one of the fundamental nuclear forensics capabilities and a prototype NNFL has been developed as one R&D topic of the project at JAEA. Main objective of a NNFL is to determine whether a seized nuclear or other radioactive material from nuclear security event (e.g. illicit trafficking) is originated from a country or not. Analytical data of the seized material are compared with the existing materials populated in a NNFL, and its attributions such as origin and history will be identified. This paper describes the current status and future plan on the development of prototype NNFL. The outline and the results of the participation in an international table top exercise on NNFL named "Galaxy Serpent" were also reported in the present paper.
Kimura, Yoshiki; Shinohara, Nobuo; Sato, Kaneaki; Toda, Nobufumi; Shinoda, Yoshiharu; Watahiki, Masaru; Kuno, Yusuke
Proceedings of INMM 54th Annual Meeting (CD-ROM), 7 Pages, 2013/07
Japan Atomic Energy Agency (JAEA) that possesses sufficient analytical capabilities to fulfil the mission of nuclear forensics technology development has started R&D project from JFY 2011. The R&D of the nuclear forensics technology at JAEA covers the development of analytical technology such as isotope and impurity measurements, morphology analysis, age determination technique, and proto-type of national nuclear forensics library. Each topic of the R&D has been promoted under the international cooperation with US-DOE. This paper will present the present status and brief results of the R&D project on nuclear forensics analytical technology and nuclear forensics library at JAEA. Some future plan of the R&D such as attribute identification of Japanese nuclear materials, data populating plan for existing nuclear materials data in JAEA fuel cycle facilities will be also introduced in the presentation.
Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Japanese Journal of Applied Physics, 51(4), p.048003_1 - 048003_2, 2012/04
Times Cited Count：2 Percentile：8.93(Physics, Applied)A proton beam driven by a repetitive high-intensity-laser is utilized to induce a 
Li(p,n)Be nuclear reaction. The total activity of Be are evaluated by two different methods. The activity obtained measuring the decay 
-rays after 1912 shots at 1 Hz is 1.7
0.2 Bq. This is in good agreement with 1.60.3 Bq evaluated from the proton energy distribution measured using a time-of-flight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system.
Hoffheins, B.; Miyaji, Noriko; Asano, Takashi; Nagatani, Taketeru; Ishiyama, Koichi; Kimura, Takashi; Kodani, Yoshiki
Proceedings of INMM 52nd Annual Meeting (CD-ROM), 10 Pages, 2011/07
Following Japan's conclusion of the Additional Protocol and the IAEA's broader conclusion regarding the peaceful nature of Japan's nuclear activities, the Japan government and facility operators have worked with the IAEA to apply integrated safeguards to increase inspection efficiency and to ensure verification correctness and completeness. These safeguards approaches rely heavily on the implementation of advanced technologies such as unattended surveillance and non-destructive assay measurement, automated nuclear material accounting, solution monitoring and remote monitoring. These technologies have enabled random interim inspections; they have also reduced the level of effort required for nuclear material accounting and inspection activities. A more comprehensive understanding of the impact of advanced technologies on operation and inspection processes would be useful for developing methodologies to support better system design and evaluation of existing systems.
-doped mixed scandium garnetsOkada, Hajime; Tanaka, Momoko; Kiriyama, Hiromitsu; Nakai, Yoshiki*; Ochi, Yoshihiro; Sugiyama, Akira; Daido, Hiroyuki; Kimura, Toyoaki*; Yanagitani, Takagimi*; Yagi, Hideki*; et al.
Optics Letters, 35(18), p.3048 - 3050, 2010/09
Times Cited Count：13 Percentile：53.86(Optics)Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki*; Shimomura, Takuya; Sasao, Hajime*; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Kondo, Shuji; Kanazawa, Shuhei; et al.
Reza Kenkyu, 38(9), p.669 - 675, 2010/09
This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe a low gain optical parametric chirped-pulse amplification (OPCPA) preamplifier that uses high energy, clean pulse seeding and is shown to significantly improve the contrast to better than 10
-10
relative to the peak of the main femtosecond pulse. We also report the use of a diffractive optical element for beam homogenization of a 100 J level Nd:glass green pump laser, achieving a flat-topped spatial profile with a filling factor near 80 %.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanoue, Manabu*; Kanazawa, Shuhei; Wakai, Daisuke*; Sasao, Fumitaka*; Okada, Hajime; et al.
Optics Letters, 35(10), p.1497 - 1499, 2010/05
Times Cited Count：85 Percentile：95.22(Optics)OPCPA (Optical parametric chirped-pulse amplification) operation with low gain by seeding with high energy, clean pulses is shown to significantly improve the contrast to better than 
-
in a high intensity Ti:sapphire laser system that is based on chirped pulse amplification. In addition to the high contrast broadband high energy output from the final amplifier is achieved with a flat-topped spatial profile of filling factor near 77%. This is the result of pump beam spatial profile homogenization with diffractive optical elements. Final pulse energies exceed 30-Joules indicating capability for reaching peak powers in excess of 500-TW.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.
Applied Optics, 49(11), p.2105 - 2115, 2010/04
Times Cited Count：39 Percentile：83.7(Optics)We have developed a femtosecond high intensity laser system, which combines both Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques, that produces more than 30-J broadband output energy, indicating the potential for achieving peak powers in excess of 500-TW. With a cleaned high-energy seeded OPCPA preamplifier as a front-end in the system, for the compressed pulse without pumping the final amplifier we found that the temporal contrast in this system exceeds 10
on the sub-nanosecond timescales, and is near 10
on the nanosecond timescale prior to the peak of the main femtosecond pulse. Using diffractive optical elements for beam homogenization of 100-J level high-energy Nd:glass green pump laser in a Ti:sapphire final amplifier, we have successfully generated broadband high-energy output with a near-perfect top-hat-like intensity distribution.
Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Tanoue, Manabu*; Akutsu, Atsushi; Okada, Hajime; Motomura, Tomohiro*; Kondo, Shuji; Kanazawa, Shuhei; et al.
Reza Kenkyu, 37(6), p.425 - 430, 2009/06
This paper reviews the temporal contrast and spatial beam quality improvement techniques in a high intensity Ti:sapphire laser system that is based on chirped-pulse amplification (CPA). We describe an optical parametric chirped-pulse amplification (OPCPA) preamplifier that is seeded by a cleaned high-energy pulse. It demonstrates a background amplified spontaneous emission (ASE) level of 10 relative to the peak main femtosecond pulse on the picosecond timescale. We also report a cryogenically-cooled Ti:sapphire final amplifier which generates focused peak intensity in excess of 10
W/cm
at a 10 Hz repetition rate.
Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Applied Physics Express, 2(6), p.066001_1 - 066001_3, 2009/05
Times Cited Count：14 Percentile：49.78(Physics, Applied)Protons with energies up to 3.5 MeV have been generated by a 10 Hz compact laser with an intensity of about 10 W/cm, focused on a 7.5 mm thick polyimide target. These protons were used to induce a nuclear reaction of 
B(p,n)C. A total activity of 11.1 Bq was created after 60-shot laser irradiation. The possibility of thin layer activation (TLA) using a high-intensity ultra-short pulsed laser is discussed.
