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Journal Articles

Angular distribution of $$gamma$$ rays from the $$p$$-wave resonance of $$^{118}$$Sn

Koga, Jun*; Takada, Shusuke*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Niinomi, Yudai*; Okudaira, Takuya*; et al.

Physical Review C, 105(5), p.054615_1 - 054615_5, 2022/05

 Times Cited Count:2 Percentile:69.47(Physics, Nuclear)

no abstracts in English

Journal Articles

Energy-dependent angular distribution of individual $$gamma$$ rays in the $$^{139}$$La($$n, gamma$$)$$^{140}$$La$$^{ast}$$ reaction

Okudaira, Takuya*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Niinomi, Yudai*; Sakai, Kenji; et al.

Physical Review C, 104(1), p.014601_1 - 014601_6, 2021/07

 Times Cited Count:3 Percentile:56.39(Physics, Nuclear)

Journal Articles

Development of a Gd$$_{2}$$Si$$_{2}$$O$$_{7}$$ (GPS) scintillator-based alpha imaging detector for rapid plutonium detection in high-radon environments

Morishita, Yuki; Izaki, Kenji; Kaneko, Junichi*; Yamamoto, Seiichi*; Higuchi, Mikio*; Torii, Tatsuo

IEEE Transactions on Nuclear Science, 67(10), p.2203 - 2208, 2020/10

 Times Cited Count:7 Percentile:72.9(Engineering, Electrical & Electronic)

We developed a Gd$$_{2}$$Si$$_{2}$$O$$_{7}$$ (GPS) scintillator-based alpha imaging detector and demonstrated its effectiveness by evaluating actual Pu particle and $$^{222}$$Rn progeny. The GPS scintillator plate was prepared by a sintering method. The outer dimensions of the GPS scintillator plate were 5 $$times$$ 5 cm, and the scintillator layer was approximately 50 $$mu$$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 ($$^{222}$$Rn) progeny counts were reduced by 65.3% by applying an energy window. Although the Pu/$$^{222}$$Rn progeny activity ratio was 1/51, the Pu particle was successfully identified among $$^{222}$$Rn progeny within the 5 min-measurement time. The imaging detector has an excellent ability for detecting Pu among $$^{222}$$Rn progeny. Thus, this detector is useful for alpha contamination monitoring in high-radon-background environments.

Journal Articles

Transverse asymmetry of $$gamma$$ rays from neutron-induced compound states of $$^{140}$$La

Yamamoto, Tomoki*; Okudaira, Takuya; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.

Physical Review C, 101(6), p.064624_1 - 064624_8, 2020/06

 Times Cited Count:8 Percentile:75.29(Physics, Nuclear)

Journal Articles

Measurement of the angular distribution of $$gamma$$-rays after neutron capture by $$^{139}$$La for a T-violation search

Okudaira, Takuya; Shimizu, Hirohiko*; Kitaguchi, Masaaki*; Hirota, Katsuya*; Haddock, C. C.*; Ito, Ikuya*; Yamamoto, Tomoki*; Endo, Shunsuke*; Ishizaki, Kohei*; Sato, Takumi*; et al.

EPJ Web of Conferences, 219, p.09001_1 - 09001_6, 2019/12

Parity violating effects enhanced by up to 10$$^6$$ times have been observed in several neutron induced compound nuclei. There is a theoretical prediction that time reversal (T) violating effects can also be enhanced in these nuclei implying that T-violation can be searched for by making very sensitive measurements. However, the enhancement factor has not yet been measured in all nuclei. The angular distribution of the (n,$$gamma$$) reaction was measured with $$^{139}$$La by using a germanium detector assembly at J-PARC, and the enhancement factor was obtained. From the result, the measurement time to achieve the most sensitive T-violation search was estimated as 1.4 days, and a 40% polarized $$^{139}$$La target and a 70% polarized $$^3$$He spin filter whose thickness is 70 atm$$cdot$$cm are needed. Therefore high quality $$^3$$He spin filter is developed in JAEA. The measurement result of the (n,$$gamma$$) reaction at J-PARC and the development status of the $$^3$$He spin filter will be presented.

Journal Articles

Development of an alpha dust monitor using a GPS scintillator plate

Morishita, Yuki; Kaneko, Junichi*; Higuchi, Mikio*; Izaki, Kenji; Yajima, Tatsuo*; Matsuura, Mitsugu*; Tamura, Ken; Torii, Tatsuo

Radiation Measurements, 122, p.115 - 120, 2019/03

 Times Cited Count:7 Percentile:66.48(Nuclear Science & Technology)

Journal Articles

Optimization of thickness of GAGG scintillator for detecting an alpha particle emitter in a field of high beta and gamma background

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Hoshi, Katsuya; Torii, Tatsuo

Radiation Measurements, 112, p.1 - 5, 2018/05

 Times Cited Count:15 Percentile:86.05(Nuclear Science & Technology)

To detect plutonium isotopes ($$^{238}$$Pu, $$^{239}$$Pu, and $$^{240}$$Pu) in a field of high beta and $$gamma$$ background, an alpha particle detector with low beta and $$gamma$$-ray sensitivity is required. Therefore, we optimized the thickness of the GAGG scintillator for alpha particle detection in a field of high beta and $$gamma$$ background. We prepared three GAGG scintillators with thicknesses of 0.05 mm, 0.07 mm, and 0.1 mm. Each of the GAGG scintillators was coupled optically to the SiPM array, which was used as the photodetector. Alpha, beta, and $$gamma$$ rays were irradiated onto the developed alpha particle detector, and their spectra were obtained. All GAGG scintillators used in this study were not sensitive to $$gamma$$ rays with a dose rate of 1 mSv/h. The beta count of the 0.05-mm-thick GAGG was only 1/100 that of the 0.1-mm-thick GAGG. Therefore, the 0.05-mm-thick GAGG scintillator is promising from the viewpoint of detecting plutonium contamination in a field with high beta and $$gamma$$ background.

Journal Articles

Flexible alpha camera for detecting plutonium contamination

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Nemoto, Norio

Radiation Measurements, 103, p.33 - 38, 2017/08

 Times Cited Count:13 Percentile:80.47(Nuclear Science & Technology)

Nuclear fuel materials, such as uranium and plutonium (Pu), are handled at nuclear fuel facilities. There are a contamination source of Pu in tight spaces that cannot be directly measured by a ZnS(Ag) scintillation detector, such as interspace between a glovebox window and a platform, pipe flange, port cover of vinyl bag, and filter interspaces. Therefore, we developed a new imaging detector called a flexible alpha camera that enables to identify the Pu contamination for tight spaces at work sites. The thickness of the flexible alpha camera was only $$sim$$1/5 of the ZnS(Ag) scintillation detector, and its efficiency for 4-pi direction was 42.7% for 5.5-MeV alpha particles. Minimal detectable activity (MDA) was 0.014 Bq. Four types of PuO$$_{2}$$ sample, removed from a duct, Bag-In/Bag-Out port, glovebox glove, and vinyl sheet, were measured by the flexible alpha camera and the PuO$$_{2}$$ particle was automatically identified. Using the flexible alpha camera, the Pu contamination source can be quickly detected, preventing the spread of contamination.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2015 (Contract research)

Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.

JAEA-Research 2016-016, 131 Pages, 2016/10


By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.

Journal Articles

Performance comparison of scintillators for alpha particle detectors

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Toi, Kohei*; Tsubota, Yoichi*; Higuchi, Mikio*

Nuclear Instruments and Methods in Physics Research A, 764, p.383 - 386, 2014/11

 Times Cited Count:34 Percentile:93.47(Instruments & Instrumentation)

Journal Articles

Development of a Si-PM based alpha camera for plutonium detection in nuclear fuel facilities

Morishita, Yuki; Yamamoto, Seiichi*; Izaki, Kenji; Kaneko, Junichi*; Toi, Kohei*; Tsubota, Yoichi*

Nuclear Instruments and Methods in Physics Research A, 747, p.81 - 86, 2014/05

 Times Cited Count:38 Percentile:95.2(Instruments & Instrumentation)

Alpha particles are monitored for detecting nuclear fuel material (i.e., plutonium and uranium) at nuclear fuel facilities. In this study, we developed a new alpha-particle imaging system by combining an Si-PM array, which is insensitive to noise, with a Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (GAGG) scintillator, and evaluated our developed system's fundamental performance. The scintillator was 0.1-mm thick, and the light guide was 3.0 mm thick. An $$^{241}$$Am source was used for all the measurements. We evaluated the spatial resolution by taking an image of a resolution chart. A 1.6 lp/mm slit was clearly resolved, and the spatial resolution was estimated to be less than 0.6-mm FWHM. The energy resolution was 13% FWHM. A slight distortion was observed in the image, and the uniformity near its center was within 24%. We conclude that our developed alpha-particle imaging system is promising for plutonium detection at nuclear fuel facilities.

JAEA Reports

Application of imaging plate to the radiation protection in the MOX fuel fabrication facility, 2; The effect of changing exposure conditions and analysis conditions

Sagawa, Naoki; Izaki, Kenji; Mizuniwa, Harumi*

JAEA-Technology 2013-029, 28 Pages, 2013/11


Developed in the Mixed Oxide fuel fabrication facility, Basic handling of IP, analysis method, detection of Pu and radioactivity quantification. These are the conditions that the exposure conditions and the analysis condition are constant. However, in the case of Contamination has occurred in the workplace, contaminated samples are not only Pu. It may contain a Pb or RnTn. Then, if other work is being carried out in a room that is the operation of IP, it's difficult to darken the room. PSL is reduced when light hits the IP. In this study, we have investigated in order to upgrade radiation protection, in the case of Containing the Pb or PSL reduction by light. Additionally, regarding change of analysis condition, the analysis method was examined when the resolution was changed to 50 micro, 100 micro and 200 micro.

JAEA Reports

Application of imaging plate to the radiation protection in the MOX fuel fabrication facility

Sagawa, Naoki; Yamazaki, Takumi; Kurosawa, Shigeyuki*; Izaki, Kenji; Mizuniwa, Harumi; Takasaki, Koji

JAEA-Technology 2010-051, 35 Pages, 2011/03


The image analysis method using a imaging plate (IP) is recent technique, and this method can get the information of radioactivity distribution by the unit of Photo Simulated Luminescence (PSL). We have investigated the PSL images obtained by measuring some plutonium samples which are radiation protection samples in order to apply imaging plate to the radiation protection at the MOX fuel facility. Plutonium spots were extracted from the PSL image extracted by the threshold, in which about 99% of the back ground was excluded, and identified by the additional requirement that the spot size is more than 40 pixels. The average background is subtracted from PSL strength of the spot area identified as Pu, and the radioactivity of the Pu spot was evaluated by multiplying the conversion calculation that is in consideration of fading.

JAEA Reports

Study on pulse height discrimination of alpha-ray using ZnS(Ag) scintillation detector; Adaptability to contamination monitoring equipments

Izaki, Kenji; Ino, Kazuo*; Mizuniwa, Harumi

JAEA-Research 2008-107, 46 Pages, 2009/03


The contamination control has been carried out by alpha-ray measurement in facilities where handling plutonium like the MOX fuel manufacturing facility and the reprocessing facility, etc. In the case of alpha-ray measurement, it is necessary to consider the influence of radon progeny that is natural radionuclide. The influence of radon progeny has been decreased by pulse height discrimination technique using the semiconductor detector as needed. However, the semiconductor detector has potentially significant problems such as the durability and noise susceptibility. Therefore the accuracy of pulse height discrimination by the ZnS(Ag) scintillation detector was confirmed as alternative to the semiconductor detector. This report shows the accuracy of pulse height discrimination technique using the ZnS(Ag) scintillation detector and evaluates the adaptability to contamination control equipments.

Journal Articles

Installation places of criticality accident detectors in the plutonium conversion development facility

Sanada, Yukihisa; Tsujimura, Norio; Shimizu, Yoshio; Izaki, Kenji; Furuta, Sadaaki

Journal of Nuclear Science and Technology, 45(Suppl.5), p.74 - 77, 2008/06

 Times Cited Count:1 Percentile:10.27(Nuclear Science & Technology)

The purpose of this study is the establishment of the determination procedures for the placements of CAAS detectors in PCDF. The dose of detection point was evaluated the simple equation which was formulated in calculated factors by MCNP and ANISN. When the alarm trip point was 2.0 mGy/h, the detection area was covered 30 m distances from the equipment to the CAD and 100 cm concrete shielding. This result will be reflected in the determination of the CAD placements and three CADs were placed in PCDF.

Journal Articles

Heavy-ion microbeam system at JAEA-Takasaki for microbeam biology

Funayama, Tomoo; Wada, Seiichi*; Yokota, Yuichiro; Fukamoto, Kana; Sakashita, Tetsuya; Taguchi, Mitsumasa; Kakizaki, Takehiko*; Hamada, Nobuyuki*; Suzuki, Michiyo; Furusawa, Yoshiya*; et al.

Journal of Radiation Research, 49(1), p.71 - 82, 2008/01

 Times Cited Count:46 Percentile:78.69(Biology)

Research concerning cellular responses to low dose irradiation, radiation-induced bystander effects, and the biological track structure of charged particles has recently received particular attention in the field of radiation biology. Target irradiation employing a microbeam represents a useful means of advancing this research by obviating some of the disadvantages associated with the conventional irradiation strategies. The heavy-ion microbeam system at JAEA-Takasaki can provide target irradiation of heavy charged particles to biological material at atmospheric pressure using a minimum beam size 5 $$mu$$m in diameter. The system can be applied to the investigation of mechanisms within biological organisms not only in the context of radiation biology, but also in the fields of general biology such as physiology, developmental biology and neurobiology, and should help to establish and contribute to the field of "microbeam biology".

Journal Articles

Development of the irradiation method for the first instar silkworm larvae using locally targeted heavy-ion microbeam

Fukamoto, Kana; Shirai, Koji*; Sakata, Toshiyuki*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kakizaki, Takehiko; Shimura, Sachiko*; Kobayashi, Yasuhiko; et al.

Journal of Radiation Research, 48(3), p.247 - 253, 2007/05

 Times Cited Count:17 Percentile:48.25(Biology)

To carry out the radio-microsurgery study using silkworm, ${it Bombyx mori}$, we have already developed the specific irradiation systems for eggs and third to fifth instar larvae. In this study, a modified application consisting of the first instar silkworm larvae was further developed using heavy-ion microbeams. This system includes aluminum plates with holes specially designed to fix the first instar silkworm larvae during irradiation, and Mylar films were used to adjust energy deposited for planning radiation doses at certain depth. Using this system, the suppression of abnormal proliferation of epidermal cells in the knob mutant was examined. Following target irradiation of the knob-forming region at the first instar stage with 180-mum-diameter microbeam of 220 MeV carbon ($$^{12}$$C) ions, larvae were reared to evaluate the effects of irradiation. The results indicated that the knob formation at the irradiated segment was specially suppressed in 5.9, 56.4, 66.7 and 73.6 % of larvae irradiated with 120, 250, 400 and 600 Gy, respectively, but the other knob formations at the non-irradiated segments were not suppressed in either irradiation. Although some larva did not survive undesired non-targeted exposure, our present results indicate that this method would be useful to investigate the irradiation effect on a long developmental period of time. Moreover, our system could also be applied to other species by targeting tissues, or organs during development and metamorphosis in insect and animals.

JAEA Reports

Investigation concerning influence of cosmic rays on criticality accident alarm system; Relationship between "Single Detection" and cosmic rays

Izaki, Kenji; Suzuki, Hideki; Tsubaki, Hirohiko; Ozeki, Kiyoshi

JAEA-Research 2007-009, 40 Pages, 2007/03


Criticality Accident Alarm System (CAAS) has been used in Nuclear Fuel Cycle Engineering Laboratories for about 20 years, and there is occurrence of the abnormal signal called "Single Detection", as an operational problem of CAAS. Radiation Protection Division has investigated the causes affecting "Single Detection", as well as reducing the influence of noises such as electromagnetic waves and power source variations. This report shows the result of the long-term observation with detectors of CAAS and describes that cosmic rays have high possibility to cause "Single Detection".

Journal Articles

Regeneration mechanism of hemopoietic organs in the silkworm, ${it Bombyx mori}$, after heavy-ion irradiation; Analysis by transplantation of the irradiated organs using a transgenic silkworm strain

Kiguchi, Kenji*; Shirai, Koji*; Sakata, Toshiyuki*; Fukamoto, Kana; Kakizaki, Takehiko; Wada, Seiichi*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Kobayashi, Yasuhiko

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 117, 2007/02

no abstracts in English

Journal Articles

Impression of "Symposium on Cosmic Radiation Exposure to Aircraft Crew"

Izaki, Kenji

Hoken Butsuri, 41(2), p.64 - 66, 2006/06

no abstracts in English

71 (Records 1-20 displayed on this page)