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Taira, Yoshitaka*; Endo, Shunsuke; Kawamura, Shiori*; Nambu, Taro*; Okuizumi, Mao*; Shizuma, Toshiyuki*; Omer, M.; Zen, H.*; Okano, Yasuaki*; Kitaguchi, Masaaki*
Physical Review A, 107(6), p.063503_1 - 063503_10, 2023/06
Times Cited Count：0 Percentile：0.01(Optics)no abstracts in English
Kitayama, Yoshiharu
Gamma Ray Imaging; Technology and Applications, p.165 - 179, 2023/00
A gamma-ray imager is a powerful tool for visualizing the distribution of radioactive materials. Recently, it has been applied to the decommissioning site of the Fukushima Daiichi Nuclear Power Station. At the decommissioning site, an imager compact, lightweight, and capable of quantitative evaluation of radioactivity is demanded. The Gamma-ray Imager using Small-Angle Scattering (GISAS) was proposed as a gamma-ray imager that meets all these requirements. GISAS consists of several shield-free directional gamma-ray detectors that detect only small-angle Compton scattering. Simulations and experiments verified the feasibility of the shield-free directional gamma-ray detectors. The shield-free directional gamma-ray detector consists of a scatterer that detects small-angle Compton scattering and an absorber that detects the scattered gamma rays. By setting an appropriate energy window for each detector, only scattering events that can be considered almost straightforward are detected. Through simulations and experiments, we have confirmed that using a silicon drift detector as the scatterer and a Gd3Al2Ga3O12 scintillator as the absorber, we can detect only small-angle Compton scattering events and obtain directionality for 662 keV gamma rays.
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo
Journal of Nuclear Engineering and Radiation Science, 7(4), p.042006_1 - 042006_7, 2021/10
Takahashi, Yoshiyuki*; Koizumi, Mitsuo
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(8), p.452 - 456, 2020/08
no abstracts in English
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06
Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm
placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.
Seya, Michio; Naoi, Yosuke; Kobayashi, Naoki; Nakamura, Takahisa; Hajima, Ryoichi; Soyama, Kazuhiko; Kureta, Masatoshi; Nakamura, Hironobu; Harada, Hideo
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01
The Integrated Support Center for Nuclear Non-proliferation and Nuclear Security (ISCN) of Japan Atomic Energy Agency (JAEA) has been conducting (based on collaborations with JAEA other centers) the following basic technology development programs of advanced non-destructive detection/measurement of nuclear material for nuclear security and nuclear non-proliferation. (1) The demonstration test of the Pu-NDA system for spent fuel assembly using PNAR and SINRD (JAEA/USDOE(LANL) collaboration, completed in JFY2013), (2) Basic development of NDA technologies using laser Compton scattered 
-rays (Demonstration of an intense mono-energetic -ray source), (3) Development of alternative to He-3 neutron detection technology, (4) Development of neutron resonance densitometry (JAEA/JRC collaboration)This paper introduces above programs.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1331, 2014/10
A high intensity -ray source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. A beamline and an experimental hatch are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 842, 2014/10
In order to demonstrate accelerator and laser technologies required for a laser Compton scattering (LCS) photon generation, a LCS photon source is under construction at the Compact ERL (cERL). We considered the flux monitors for the adjustment LCS photon source. A thin scintillator detector and a silicon drift detector are employed as flux monitors and are installed at the upstream part of the LCS beamline. The background signal level due to the bremsstrahlung of the electron beam was measured by a CsI(pure) scintillator. In the result of the measurement, the background signal is acceptable level for the flux monitors.
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Honda, Yosuke*; Kosuge, Atsushi*; Urakawa, Junji*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1940 - 1942, 2014/07
In order to demonstrate required accelerator and laser technologies for a high intensity -ray source from the laser Compton scattering (LCS), an LCS photon source and the peripheral equipment are under construction at the Compact ERL (cERL) at High Energy Accelerator Research Organization (KEK). The LCS photon source by an electron beam in the energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear species. The LCS photon source and the peripheral equipment consist of a mode-locked fiber laser, laser enhancement cavity, beamline, and experimental hatch. The commissioning of the LCS photon source will be started in February 2015.
Kawano, Yasunori
Denki Gakkai Gijutsu Hokoku, Dai-1018-Go, p.25 - 29, 2005/05
Aims of "The Investigation Committee on Pulsed Power Generation and Application" are to investigate recent developments on generation and control of pulsed power, to clarify the technological issues, and to provide the future prospects of such research area. This paper is written as the "section 3.3 Optical Diagnostics" in the technical report of the committee. Here, "diagnostics of relativistic electron beam in a torus plasma by laser inverse Compton scattering" is reported. This method has been newly proposed by JAERI for active measurement of the energy distribution of runaway electrons in a tokamak plasma. The paper presents the basic properties of scattered photons estimated in the case of runaway electron beam observed in JT-60U (number of beam electrons=2e17 electrons, beam electron energy = 30 MeV). For instance, when we use the fundamental YAG laser with the energy of 10 J/pulse and pulse widths of 1 ns, maximum energy of scattered photons would be in the X-ray region, and the signal to noise ratio can be estimated as 
3. It is also mentioned that the development of the pulse X-ray imaging spectroscopy is required for this diagnostics method.
Kawano, Yasunori; Nakano, Tomohide; Isayama, Akihiko; Hatae, Takaki; Konoshima, Shigeru; Oyama, Naoyuki; Kondoh, Takashi; Tamai, Hiroshi; Kubo, Hirotaka; Asakura, Nobuyuki; et al.
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
In order to mitigate the post-disruption runaway electrons, experiments has been carried out with impurity pellet injection. As a result, we have observed the prompt exhaust of the runaway electrons and the reduction of runaway plasma. We have presented one possible explanation for basic behavior of the runaway plasma current that it follows the balance of the avalanche generation of runaway electrons and their slowing down predicted by the model, including effects by synchrotron radiation. On the other hand, standing on the fact that the current quench time is extended by runaway electrons, the experiment for avoiding the current quench by runaway electrons has been carried out. The runaway electrons reinforced the discharge to survive against the low Te of less than several tens eV and an additional impurity pellet injection, and thus the plasma current was maintained and terminated as programmed. To study the dynamics of runaway electrons precisely, a new active and direct diagnostic concept using the laser inverse Compton scattering has been proposed.
-rays produced in laser-induced compton-backscatteringHirade, Tetsuya; Toyokawa, Hiroyuki*; Odaira, Toshiyuki*; Suzuki, Ryoichi*; Ogaki, Hideaki*
Materials Science Forum, 445-446, p.474 - 476, 2004/02
Positron annihilation methods are very unique and strong tools to investigate materials. However, positrons are usually injected from outside of the samples. Therefore the samples should be in a vacuum or radioisotopes should be attached. Recently, Selim et al. applied high-energy g-rays (2MeV) produced by use of 6MeV electron linac to create positrons in thick materials. We have also been trying a similar method. In our case, high-energy -rays (20MeV) produced in laser-induced Compton-backscattering are applied for positron creation in samples. The -rays do not spread and penetrate straightly in air. When you place a sample on the path of -rays, positrons are created in the sample and usual positron annihilation methods can be applied. Moreover, It is not needed to place the samples in vacuum and radioisotopes are not necessary. It means that the measurements of very high temperature materials such as metals near/over melting points will be possible. The detail of this method and some examples of experimental results will be introduced.
Radioisotopes, (36), p.49 - 56, 1987/00
no abstracts in English
Nagai, Ryoji; Hajima, Ryoichi; Shizuma, Toshiyuki; Mori, Michiaki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*
no journal, ,
no abstracts in English
Seya, Michio
no journal, ,
This oral presentation introduces present status of development activities in Europe, United States of America and in Japan of non-destructive detection technologies, which are required for member states in IAEA Nuclear Security Series No.15 (Nuclear Security Recommendations on Nuclear and Other Radioactive Material out of Regulatory Control). Also, the NDA technologies presently applied to IAEA safeguards as well as development program of spent fuel Pu NDA technologies of NGSI (Next Generation Safeguards Initiative) of DOE are explained. In addition, among development activities of JAEA relating nuclear security and nuclear safeguards, development of laser Compton scattered -ray source and NRF (Nuclear Resonance Fluorescence) -NDA technologies using LCS -rays and also development of NRD (Neutron Resonance Densitometry) technologies are presented.
-raysMori, Michiaki; Kosuge, Atsushi*; Hajima, Ryoichi; Nagashima, Keisuke; Kondo, Kiminori; Kiriyama, Hiromitsu
no journal, ,
We report on a high average power Yb-fiber CPA laser system. The system can produces an average power of 100 W class at 160 MHz in a 5 ps pulse with narrow bandwidth of 0.4 nm in full-width-half-maximum. The bandwidth of the laser beam can be varied (from 0.4 nm to 2 nm) easily by changing the configuration of a spectrum mask at a secondary pulse stretcher. The power fluctuation is only 0.6% (rms value), which was measured over a period of 10 hours. The excellent beam profile is preserved over the full range of average power. The reliable, efficient, and compact our fiber laser system is currently being applied to realize intense LCS -ray source.
-raysHajima, Ryoichi; Seya, Michio
no journal, ,
Monochromatic -rays produced by laser Compton scattering could be used for detection of nuclear material with cobined use of nuclear resonance flourescence. By using ERL (Energy Recovery Linac) based -ray source for producing high intensity, it is possible to detect nuclear material inside an heavily shielded object and also to have clear imaging inside of it. In this poster presentation, a prospect of application of the -ray source to nuclear material detection system.
Kirihara, Yoichi; Namito, Yoshihito*; Sanami, Toshiya*; Itoga, Toshiro*; Nakashima, Hiroshi; Miyamoto, Shuji*; Asano, Yoshihiro*
no journal, ,
no abstracts in English
Koizumi, Mitsuo; Omer, M.; Takahashi, Tone; Seya, Michio; Hajima, Ryoichi; Shizuma, Toshiyuki; Hashimoto, Satoshi*; Amano, So*; Miyamoto, Shuji*
no journal, ,
JAEA, QST, and University of Hyogo are developing a nuclear material detection technique that utilizes a measurement method of nuclear resonance fluorescence gamma-ray scattering induced by laser Compton scattering gamma-ray beams, under the subsidiary for "promotion of strengthening nuclear security or the like" of MEXT. So far, experimental apparatus, a laser system, gamma-ray detectors, data acquisition systems, and so on, are prepared for a demonstration experiment to be performed at NEW SBARU facility of University of Hyogo. An imitated nuclear material sample hidden in a shield will be placed on an automatic stage. This presentation overview the purpose of this program, preparation status, plan of demonstration experiments and a workshop.
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki
no journal, ,
no abstracts in English
