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Journal Articles

Investigation of using a long-life electronic personal dosimeter for monitoring aviation doses of frequent flyers

Yasuda, Hiroshi*; Yajima, Kazuaki*; Sato, Tatsuhiko

Radiation Measurements, 134, p.106309_1 - 106309_4, 2020/06

 Times Cited Count:1 Percentile:24.17(Nuclear Science & Technology)

We have investigated an application of a recently developed electronic personal dosimeter (D-Shuttle) for aviation dosimetry. As results of measurements in four long-haul flights between Japan and Germany, the D-Shuttle indicated values were in the range of 25 to 30% of the total H$$^{*}$$(10) values estimated by a route-dose calculations program JISCARD EX. Though we need more measurements and analyses under different flight conditions to conclude, according to these results obtained so far, it would be possible to perform monitoring of the annual aviation doses of frequent flyers by using D-Shuttle on an individual basis.

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:1 Percentile:30.13(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:4 Percentile:25.43(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Nowcast and forecast of galactic cosmic ray (GCR) and solar energetic particle (SEP) fluxes in magnetosphere and ionosphere; Extension of WASAVIES to earth orbit

Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Miyoshi, Yoshizumi*; Ueno, Haruka*; Nagamatsu, Aiko*

Journal of Space Weather and Space Climate (Internet), 9, p.A9_1 - A9_11, 2019/03

 Times Cited Count:2 Percentile:49.6(Astronomy & Astrophysics)

Real-time estimation of astronaut doses during solar particle events (SPE) is one of the most challenging tasks in cosmic-ray dosimetry. We therefore develop a new computational method that can nowcast the solar energetic particle (SEP) as well as galactic cosmic-ray (GCR) fluxes on any Earth orbit during a large SPE associating with ground level enhancement. It is an extended version of WArning System for AVIation Exposure to Solar Energetic Particle, WASAVIES. The extended version, called WASAVIES-EO, can calculate the GCR and SEP fluxes outside a satellite based on its two-line element data. Moreover, organ dose and dose-equivalent rates of astronauts in the International Space Station (ISS) can be estimated using the system, considering its shielding effect. The accuracy of WASAVIES-EO was validated based on the dose rates measured in ISS, as well as based on high-energy proton fluxes observed by POES satellites.

Journal Articles

Real time and automatic analysis program for WASAVIES; Warning system for aviation exposure to solar energetic particles

Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*

Space Weather, 16(7), p.924 - 936, 2018/07

 Times Cited Count:7 Percentile:28.73(Astronomy & Astrophysics)

A physics-based warning system of aviation exposure to solar energetic particles, WASAVIES, is improved to be capable of real-time and automatic analysis. In the improved system, the count rates of several neutron monitors (NM) at the ground level, as well as the proton fluxes measured by the GOES satellite are continuously downloaded at intervals of 5 min and used for determining the model parameters. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. A web-interface of WASAVIES is also developed and will be released in the near future through the public server of NICT.

Journal Articles

Summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident

Iimoto, Takeshi*; Kinoshita, Norikazu*; Sakaguchi, Aya*; Sugihara, Shinji*; Takamiya, Koichi*; Tagami, Keiko*; Nagao, Seiya*; Bessho, Kotaro*; Matsumura, Hiroshi*; Miura, Taichi*; et al.

KEK Report 2016-3, 134 Pages, 2017/03

This report is summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident. It was compiled efforts related to the accident reported from the 13th to the 17th "Workshop on Environmental Radioactivity" which was held at the High Energy Accelerator Research and Development Organization.

Journal Articles

Development of micro-structured fluorescent plates for high-resolution imaging

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Matsubayashi, Masahito

JPS Conference Proceedings (Internet), 11, p.020005_1 - 020005_6, 2016/11

Journal Articles

Using LiF crystals for high-performance neutron imaging with micron-scale resolution

Faenov, A.*; Matsubayashi, Masahito; Pikuz, T.*; Fukuda, Yuji; Kando, Masaki; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Sakai, Takuro; Shiozawa, Masahiro*; et al.

High Power Laser Science and Engineering, 3, p.e27_1 - e27_9, 2015/10

 Times Cited Count:7 Percentile:50.14(Optics)

Journal Articles

Medaka blastoderm cells are capable of compensating the injured cells irradiated by carbon-ion micro-beam

Yasuda, Takako*; Oda, Shoji*; Asaka, Tomomi*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Yasuhiko; Mitani, Hiroshi*

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 85, 2015/03

In this present study, we examined the effects of heavy carbon-ions on development in pre-implantation period utilizing medaka blastula stage embryos (st. 11: blastderm diameter is about 500 $$mu$$m). We performed targeted irradiation by carbon-ion micro-beam (diameters of 120, 180 $$mu$$m) to a central parts of blastoderm and observed the abnormalities during development compared with whole-body irradiated embryos. As a results, retardation and characteristic malformed eyes were observed during development when blastoderm cells were partially irradiated, However, more than half of 50 Gy-irradiated embryos (area size=120 $$mu$$m diameter) could hatch normally in contrast to all embryos with 2 Gy of whole-body irradiation being lethal before hutching.

Journal Articles

Air shower simulation for WASAVIES; Warning system for aviation exposure to solar energetic particles

Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Yashiro, Seiji*; Kuwabara, Takao*; Shiota, Daiko*; Kubo, Yuki*

Radiation Protection Dosimetry, 161(1-4), p.274 - 278, 2014/10

 Times Cited Count:17 Percentile:12.12(Environmental Sciences)

We applied our simulation technique to the analysis of air shower induced by mono-energetic protons and alpha particles, which are the dominant component of SEP. The results of the simulations were summarized in a database containing particle fluxes for each condition as a function of the atmospheric depth. This database was then incorporated into our developing Warning System of AVIation Exposure to SEP called WASAVIES. In this system, the aircrew doses due to SEP exposure are estimated within 6 hours after the flare onset, using the established database multiplied with the SEP fluxes incident to the earth. The MHD Cube model is employed in the determination of the incident SEP fluxes. The procedures for the air shower simulation together with some initial results of the aircrew dose calculations for past ground-level enhancement (GLE) events will be presented at the meeting.

Journal Articles

Fabrication of fine imaging devices using an external proton microbeam

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Koka, Masashi; Sato, Takahiro; Ishii, Yasuyuki; Oshima, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 332, p.238 - 241, 2014/08

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

We have successfully fabricated novel microscopic imaging devices made from UV/EB curable resin using an external scanning proton microbeams. The devices are micro-structured fluorescent plates that consist of an array of micro-pillars that align periodically. The base material used in the pillars is UV/EB curable resin and each pillar contains phosphor grains. The pattern exposures were performed using a proton beam writing technique. The height of the pillars depends on the range of the proton beam. Optical microscopy and scanning electron microscopy have been used to characterize the samples. The results show that the fabricated fluorescent plates are expected to be high-spatial-resolution imaging devices.

Journal Articles

Radiation dose forecast of WASAVIES during ground-level enhancement

Kataoka, Ryuho*; Sato, Tatsuhiko; Kubo, Yuki*; Shiota, Daiko*; Kuwabara, Takao*; Yashiro, Seiji*; Yasuda, Hiroshi*

Space Weather, 12(6), p.380 - 386, 2014/06

 Times Cited Count:13 Percentile:47.1(Astronomy & Astrophysics)

Solar energetic particles (SEP) sometimes induce air shower that significantly increase the radiation dose at flight altitudes. In order to inform the situation of such a space radiation hazard to aircrews, a physics-based forward model is developed as WASAVIES (Warning System for Aviation Exposure to SEP) based on the focused transport equation and Monte Carlo particle transport simulation of the air shower. WASAVIES gives the fastest and simplest way to predict the time profile of dose rate during ground-level enhancements (GLEs).

Journal Articles

Observation of fallout deposition in an outdoor swimming pool 50 km away from the Fukushima Daiichi Nuclear Power Plant

Saegusa, Jun; Yasuda, Ryo; Kurikami, Hiroshi

Radiation Measurements, 60, p.53 - 58, 2014/01

 Times Cited Count:5 Percentile:51.92(Nuclear Science & Technology)

After the Fukushima Daiichi Nuclear Power Plant (NPP) accident, the fallout deposited in an outdoor swimming pool was observed. At a pool situated 50 km away from the NPP, the average concentrations of radiocesium for the water and sediment were quantified as 170 Bq L$$^{-1}$$ and 3.6$$times$$10$$^{5}$$ Bq kg$$^{-1}$$, respectively. Taking account of these concentrations and of the water balance in and around the pool, the deposition density of radiocesium, as of August 2011, was precisely estimated to be 0.32$$pm$$0.03 MBq m$$^{-2}$$ ($$k$$ = 1). The density corroborated the previous results obtained by the other methods, i.e., airborne surveys, in-situ Ge surveys and soil samplings at neighboring locations. The radioactivity concentrations of $$^{89}$$Sr, $$^{90}$$Sr, $$^{238}$$Pu and $$^{239+240}$$Pu in the water were all less than the minimum detectable activities - 2, 0.1, 0.002 and 0.002 Bq L$$^{-1}$$, respectively.

Journal Articles

Micromachining of commodity plastics by proton beam writing and fabrication of spatial resolution test-chart for neutron radiography

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Matsubayashi, Masahito; Kada, Wataru; Koka, Masashi; Sato, Takahiro; Okubo, Takeru; Ishii, Yasuyuki; et al.

Nuclear Instruments and Methods in Physics Research B, 306, p.299 - 301, 2013/07

 Times Cited Count:7 Percentile:41.73(Instruments & Instrumentation)

Journal Articles

Decontamination of outdoor school swimming pools in Fukushima after the nuclear accident in March 2011

Saegusa, Jun; Kurikami, Hiroshi; Yasuda, Ryo; Kurihara, Kazuo; Arai, Shigeki; Kuroki, Ryota; Matsuhashi, Shimpei; Ozawa, Takashi; Goto, Hiroaki; Takano, Takao; et al.

Health Physics, 104(3), p.243 - 250, 2013/03

 Times Cited Count:3 Percentile:68.05(Environmental Sciences)

After the Nuclear accident on March 2011, water discharge from many outdoor swimming pools in the Fukushima prefecture was suspended out of concern that radiocesium in the pool water would flow into farmlands. We have reviewed the existing flocculation method for decontaminating pool water and established a practical decontamination method by demonstrating the process at several pools in the Fukushima prefecture.

Journal Articles

A Line pair indicator made of Gd film for evaluating spatial resolution

Yasuda, Ryo; Matsubayashi, Masahito; Sakai, Takuro; Nojima, Takehiro; Iikura, Hiroshi; Katagiri, Masaki*; Takano, Katsuyoshi*; Pikuz, T.; Faenov, A.*

Physics Procedia, 43, p.196 - 204, 2013/00

 Times Cited Count:1 Percentile:41.32

Journal Articles

Investigation of the brightness enhancement using brightness enhancement films on a scintillator

Iikura, Hiroshi; Tsutsui, Noriaki*; Saito, Yasushi*; Nojima, Takehiro; Yasuda, Ryo; Sakai, Takuro; Matsubayashi, Masahito

Physics Procedia, 43, p.161 - 168, 2013/00

 Times Cited Count:2 Percentile:25.19

Journal Articles

Development of an imaging system for the observation of water behavior in a channel in PEFC

Nojima, Takehiro; Yasuda, Ryo; Takenaka, Nobuyuki*; Katagiri, Masaki*; Iikura, Hiroshi; Sakai, Takuro; Matsubayashi, Masahito

Physics Procedia, 43, p.282 - 287, 2013/00

 Times Cited Count:2 Percentile:25.19

We developed a new imaging system for observing the water distribution in Polymer Electrolyte Fuel Cell (PEFC) under operation. This imaging system realizes both low noise and high sensitivity imaging and it enables to obtain an image in relatively short exposure time. This imaging system consists of EM-CCD (Electron Multiplication-Charged Coupled Device) camera, a LiF/ZnS scintillator screen and slit system. The EM-CCD camera has wide dynamic range and high sensitivity. The brightness of the scintillator screen is about three times higher than that of conventional type. The slit system was used for reducing the white dot noise caused by primary and/or secondary prompt $$gamma$$ rays. A characteristic test of this imaging system using JARI (Japan Automobile Research Institute)-standard cell was carried out at TNRF. In the results of the test, qualitative and quantitative observation of water behavior in the channel of PEFC was archived by the new imaging system.

Journal Articles

Development of a high-performance optical system and fluorescent converters for high-resolution neutron imaging

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Matsubayashi, Masahito

Physics Procedia, 43, p.223 - 230, 2013/00

 Times Cited Count:0 Percentile:100

JAEA Reports

Guide for decontaminating swimming pool at schools

Matsuhashi, Shimpei; Kurikami, Hiroshi; Yasuda, Ryo; Takano, Takao; Seko, Noriaki; Naganawa, Hirochika; Kuroki, Ryota; Saegusa, Jun

JAEA-Testing 2011-007, 189 Pages, 2012/07


Because of TEPCO Fukushima Dai-ichi Nuclear Power Plant accident due to the Great East Japan Earthquake, a huge amount of radioactive materials was widely dispersed and precipitated into the environment. Swimming pools in Fukushima prefectures were contaminated with the radioactives. We JAEA carried out several demonstration tests to decontaminate the radioactives and discharge the pool water safely. We concluded the results obtained from the tests as "Guide for decontaminating swimming pool at school" and released it quickly. Following this, we also released the guide in English. This manuscript, as an experimental report of the swimming pool water decontamination, is consisted from the guide in Japanese and English prepared.

141 (Records 1-20 displayed on this page)