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Journal Articles

Feasibility study of the one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042002_1 - 042002_7, 2021/10

For the application in the measurement of the high dose rate hot spots inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, we propose a novel one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding. The proposed method estimates the incident position of radiation to the fiber by the unfolding of the wavelength spectrum output from the fiber edge using the fact that the attenuation length of light along the fiber depends on the wavelength. Because this method measures the integrated light intensity, this method can avoid the problem of counting loss and signal pile-up, which occurs in the radiation detector with pulse counting mode under high dose rate field. Through basic experiments using the ultraviolet light source and $$^{90}$$Sr/$$^{90}$$Y radioactive point source, basic properties of source position detection were confirmed.

Journal Articles

Development of one-dimensional optical fiber type radiation distribution sensing method based on wavelength spectrum unfolding

Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo

Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05

Journal Articles

Communication-overlap techniques for improved strong scaling of gyrokinetic Eulerian code beyond 100k cores on the K-computer

Idomura, Yasuhiro; Nakata, Motoki; Yamada, Susumu; Machida, Masahiko; Imamura, Toshiyuki*; Watanabe, Tomohiko*; Nunami, Masanori*; Inoue, Hikaru*; Tsutsumi, Shigenobu*; Miyoshi, Ikuo*; et al.

International Journal of High Performance Computing Applications, 28(1), p.73 - 86, 2014/02

 Times Cited Count:17 Percentile:76.3(Computer Science, Hardware & Architecture)

Journal Articles

Development of numerical techniques toward extreme scale fusion plasma turbulence simulations

Idomura, Yasuhiro; Nakata, Motoki; Yamada, Susumu; Machida, Masahiko; Imamura, Toshiyuki*; Watanabe, Tomohiko*; Nunami, Masanori*; Inoue, Hikaru*; Tsutsumi, Shigenobu*; Miyoshi, Ikuo*; et al.

Proceedings of 31st JSST Annual Conference; International Conference on Simulation Technology (JSST 2012) (USB Flash Drive), p.234 - 242, 2012/09

Journal Articles

Formation of a uniform ion beam using multipole magnets

Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Okumura, Susumu; Ishibori, Ikuo; Yokota, Wataru; Watanabe, Shinichi*; Kubono, Shigeru*; Oshiro, Yukimitsu*

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.3895 - 3897, 2009/05

Journal Articles

Ablation-initiated isotope-selective atomic absorption spectroscopy of lanthanide elements

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

AIP Conference Proceedings 1104, p.30 - 35, 2009/03

no abstracts in English

JAEA Reports

Resonance absorption spectroscopy for laser-ablated lanthanide atom, 1; Optimized experimental conditions for isotope-selective absorption of gadolinium (Contract research)

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

JAEA-Research 2008-056, 24 Pages, 2008/06

JAEA-Research-2008-056.pdf:5.1MB

For remote isotope analysis of low-decontaminated TRU fuel, we are developing an analytical technique on the basis of the resonance absorption spectroscopy for the laser-ablation plume. To improve isotopic selectivity and detection sensitivity of this technique, we measured absorption spectra of Gd atom with various conditions. As a result, high resolution spectrum was obtained from the observation of slow component of the plume produced under low-pressure rare-gas ambient. The observed narrowest linewidth of about 0.85 GHz was found to be close to the Doppler width estimated for Gd atom of room temperature. Furthermore, relaxation rate of higher meta-stable state was found to be faster than that of ground state, suggesting that use of the transition arising from ground state or lower meta-stable state is preferable for highly sensitive isotope analysis.

Journal Articles

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

Journal Articles

Development of frequency stabilized diode laser based on a spectroscopic study on magnetically induced circular dichroism of atomic rubidium

Miyabe, Masabumi; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo; Wendt, K.*

Japanese Journal of Applied Physics, Part 1, 45(5A), p.4120 - 4122, 2006/05

 Times Cited Count:2 Percentile:8.74(Physics, Applied)

We developed a frequency-stabilized diode laser using magnetically induced circular dichroism. From a spectroscopic study on Rb-${it D}$ $$_{2}$$ line, the most stable Doppler-broadened and Doppler-free lines were determined to be the transition from ${it F}$g=2 ground state of $$^{85}$$Rb and the crossover resonance from ${it F}$g=3 ground state to ${it F}$e=3 and 4 excited states of $$^{85}$$Rb respectively. Furthermore, we measured the fluctuation of the laser locked to the Doppler-free line to be $$pm$$50kHz/8hour and thus revealed the applicability to a several-hours stabilization. The developed laser can be used as a reference laser for frequency stabilization system for multiple tunable lasers for RIMS analysis.

Journal Articles

Development of RIMS apparatus for isotope analysis of Calcium nuclear waste materials

Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

Journal of Nuclear Science and Technology, 43(4), p.305 - 310, 2006/04

 Times Cited Count:13 Percentile:65.92(Nuclear Science & Technology)

We are developing an resonance ionization spectrometric apparatus aiming at an analysis of a radioactive isotope of calcium ($$^{41}$$Ca) in nuclear waste materials. The developed system consists of the reference laser whose frequency was locked on a Doppler-free absorption line of 85Rb and the computer-controlled fringe offset lock system which transfer frequency stability of the reference laser to slave lasers for Ca excitation. With heterodyne spectroscopy and laser induced fluorescence spectroscopy of Ca, it was confirmed that the developed apparatus was suitable for resonance ionization spectrometric analysis.

Journal Articles

Determination of ionization potential of calcium by high-resolution resonance ionization spectroscopy

Miyabe, Masabumi; Geppert, C.*; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo; Wendt, K. D. A.*

Journal of the Physical Society of Japan, 75(3), p.034302_1 - 034302_10, 2006/03

 Times Cited Count:17 Percentile:66.04(Physics, Multidisciplinary)

High-resolution resonance ionization spectroscopy has been utilized to determine a precise ionization potential of Ca. Three-step resonance excitation with single-mode extended cavity diode lasers populates long and unperturbed Rydberg series of 4snp (1P1) and 4snf (1F3) states in the rage of n=20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm$$^{-1}$$ with the accuracy improved one order of magnitude higher than previously reported ones.

JAEA Reports

Development of frequency stabilized laser system for long-lived isotope analysis, 3; Computer-based laser frequency tuning system

Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

JAERI-Tech 2005-043, 27 Pages, 2005/08

JAERI-Tech-2005-043.pdf:2.51MB

Multi-step resonance ionization spectrometry for long-lived nuclei in nuclear waste materials requires laser sources having high frequency stability and tunability. In this study we have developed a novel frequency control system consisting of digital circuitry and computer to improve the frequency tunability of the developed laser stabilization system using dichroic atomic vapor laser lock (DAVLL) and fringe offset lock (FOL) techniques. Based on the heterodyne experiment and multi-step laser induced fluorescence spectroscopy of atomic Ca, the frequency stability and tunability of the developed system were evaluated.

JAEA Reports

Determination of the $$^{40}$$Ca ionization potential by high-precision three-step resonance ionization spectroscopy

Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

JAERI-Research 2004-023, 17 Pages, 2004/11

JAERI-Research-2004-023.pdf:2.71MB

High precision resonance ionization spectroscopy has been applied to determination of an accurate ionization potential of $$^{40}$$Ca. Three-step resonant excitation with single-mode extended cavity diode lasers populates a series of ${it 4snp}$ ($$^{1}$$P$$_{1}$$) and ${it 4snf}$ ($$^{1}$$F$$_{3}$$) Rydberg states in the rage of ${it n}$=20-150. By using an extended Ritz formula for quantum defect, the series convergence limit has been determined to be 49305.9240 (20) cm$$^{-1}$$ with the accuracy improved one order of magnitude higher than previously reported ones.

JAEA Reports

Development of frequency stabilized laser system for long-lived isotope analysis, 2; Simultaneous locking system for multiple diode lasers using Zeeman effect and interferometer

Miyabe, Masabumi; Kato, Masaaki; Oba, Masaki; Wakaida, Ikuo; Watanabe, Kazuo

JAERI-Tech 2004-065, 19 Pages, 2004/10

JAERI-Tech-2004-065.pdf:0.99MB

In nuclear waste materials there are various radionuclides to which standard analytical techniques are difficult to be applied. We are developing an analytical technique where such nuclides are ionized and mass-analyzed using diode laser based multi-step RIMS technique. The diode laser, however, has one drawback, i.e. its oscillation wavelength is readily drifted by acoustic, electric and optical noise, and thus the laser without frequency stabilization is not suitable for the analysis. In this study, we have developed (1) the diode laser whose frequency is stabilized to an intense absorption line of Rb by Zeeman effect and (2) the stabilization system where diode lasers for 3-step ionization of Ca are locked to the Rb-stabilized laser using a Fabry-perot interferometer. Additionally, to evaluate overall frequency stability of the stabilization system, fluctuations in the photoion and fluorescence signals arising from 3-step RIMS of Ca were simultaneously observed.

JAEA Reports

Development of frequency stabilized laser system for long-lived isotope analysis, 1; Development of Littrow configuration extended cavity diode laser

Miyabe, Masabumi; Oda, Koichi*; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

JAERI-Tech 2004-064, 33 Pages, 2004/10

JAERI-Tech-2004-064.pdf:1.89MB

In nuclear waste materials there are various radionuclides to which standard analytical techniques are difficult to be applied. We are developing an analytical technique where such nuclides are analyzed using multi-step resonance ionization mass spectrometry. In this study, we have developed an external cavity diode laser applicable to the analysis. The wavelength and output power dependence on injection current and temperature were investigated for various types of laser diodes. Based on the data, we have obtained a suitable condition to operate the ECDL in stable single-mode oscillation, so that a continuous scanning range of about 100 GHz was realized. Additionaly, to evaluate the bandwidth of the developed ECDL, we have performed Doppler-free spectroscopy. The reasonable agreement of the measured isotope shift and HFS splitting with the reported values demonstrated that the developed ECDL is applicable to a precise laser spectroscopy as well as a laser trace analysis.

Journal Articles

Cold neutron beam focusing by a superconducting sextupole magnet

Suzuki, Junichi; Oku, Takayuki*; Adachi, Tomohiro*; Shimizu, Hirohiko*; Hirumachi, Tamiko*; Tsuchihashi, Takahiro*; Watanabe, Ikuo*

Journal of Applied Crystallography, 36(Part3, 1), p.795 - 799, 2003/01

no abstracts in English

Journal Articles

The Summary report on engineering design activities in the International Thermonuclear Experimental Reactor (ITER) project

Mori, Masahiro; Shoji, Teruaki; Araki, Masanori; Saito, Keiji*; Senda, Ikuo; Omori, Junji*; Sato, Shinichi*; Inoue, Takashi; Ono, Isamu*; Kataoka, Takahiro*; et al.

Nihon Genshiryoku Gakkai-Shi, 44(1), p.16 - 89, 2002/01

no abstracts in English

Journal Articles

Development of a 13T-46kA Nb$$_{3}$$Sn conductor and central solenoid model coils for ITER

Takahashi, Yoshikazu; Ando, Toshinari; Hiyama, Tadao; Nakajima, Hideo; Kato, Takashi; Sugimoto, Makoto; Isono, Takaaki; Oshikiri, Masayuki*; Kawano, Katsumi; Koizumi, Norikiyo; et al.

Fusion Engineering and Design, 41(1-4), p.271 - 275, 1998/09

 Times Cited Count:4 Percentile:38.7(Nuclear Science & Technology)

no abstracts in English

Oral presentation

High-resolution resonance ionization mass spectrometry for isotope analysis of calcium

Miyabe, Masabumi; Wakaida, Ikuo; Oba, Masaki; Kato, Masaaki; Watanabe, Kazuo

no journal, , 

We have developed a frequency stabilized laser system for RIMS analysis of a long-lived radionuclide of calcium (41Ca) in concrete waste materials. A stable reference laser has been developed using magnetically induced circular dichroism of atomic rubidium. The frequency stability was estimated to be 50kHz over 8 hour period from beat frequency measurement. To transfer the high frequency stability to the other lasers for 3-step excitation of atomic calcium, a computer-controlled fringe offset lock system has been developed as well. By using the system precise frequency tuning of 1MHz error over 1GHz scan was realized. The overall frequency tuning precision was also confirmed by a multistep fluorescence and resonance ionization spectroscopy of calcium.

Oral presentation

Development of resonance ionization mass spectrometry for calcium radioisotope in nuclear waste materials

Miyabe, Masabumi; Oba, Masaki; Kato, Masaaki; Wakaida, Ikuo; Watanabe, Kazuo

no journal, , 

We have been developing a continuous-wave resonance ionization mass spectrometry (cw-RIMS) apparatus aiming at an analysis of $$^{41}$$Ca radioisotope in nuclear waste materials. The optimum three-step ionization schemes of Ca were investigated and the 4snf (1F3) series members of around n=35 were found to have high isotope-selectivity and efficiency under our experimental conditions. The background noise arising from the thermal ions were negligible at a furnace current of $$<$$1500K. On the basis of these results the abundance sensitivity of 8$$times$$10$$^{-8}$$ was demonstrated for $$^{46}$$Ca. Also we extended data on isotope shift and hyperfine structure of 4snf (1F3) series up to n=80.

33 (Records 1-20 displayed on this page)