Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kataoka, Ryuho*; Sato, Tatsuhiko; Kato, Chihiro*; Kadokura, Akira*; Kozai, Masayoshi*; Miyake, Shoko*; Murase, Kiyoka*; Yoshida, Rihito*; Tomikawa, Yoshihiro*; Munakata, Kazuoki*
Journal of Space Weather and Space Climate (Internet), 12, p.37_1 - 37_11, 2022/11
Times Cited Count:1 Percentile:22.72(Astronomy & Astrophysics)Solar modulation of galactic cosmic rays around the solar minimum in 2019-2020 looks different in the secondary neutrons and muons observed at the ground. To compare the solar modulation of primary cosmic rays in detail, we have to remove the possible seasonal variations caused by the atmosphere and surrounding environment. As such surrounding environment effects, we evaluate the snow cover effect on neutron count rate and the atmospheric temperature effect on muon count rate both simultaneously observed at Syowa Station in the Antarctic (69.01 S, 39.59 E). The corrected muon count rate starts decreasing in late 2019, earlier than the corrected neutron count rate which starts decreasing in early 2020, possibly indicating the rigidity dependent solar modulation in the heliosphere.
Koizumi, Takatsugu*; Honda, Fuminori*; Sato, Yoshiki*; Li, D.*; Aoki, Dai*; Haga, Yoshinori; Gochi, Jun*; Nagasaki, Shoko*; Uwatoko, Yoshiya*; Kaneko, Yoshio*; et al.
Journal of the Physical Society of Japan, 91(4), p.043704_1 - 043704_5, 2022/04
Times Cited Count:2 Percentile:46.35(Physics, Multidisciplinary)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:7 Percentile:38.79(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.
Sato, Tatsuhiko; Nagamatsu, Aiko*; Ueno, Haruka*; Kataoka, Ryuho*; Miyake, Shoko*; Takeda, Kazuo*; Niita, Koji*
Radiation Protection Dosimetry, 180(1-4), p.146 - 149, 2018/08
Times Cited Count:14 Percentile:81.7(Environmental Sciences)Cosmic-ray dose rates spatially and temporally change very much. In this study, we compared the calculated cosmic-ray environments on the Earth, Moon, and Mars as well as inside spacecraft on low-earth orbit (LEO) and at interplanetary space. In the calculation, a galactic cosmic-ray model developed in DLR and trapped proton/electron models AP9/AE9 were used for determining the incident cosmic-ray fluxes, and the Particle and Heavy Ion Transport code System, PHITS, was employed for the cosmic-ray transport simulation in the Earth, Lunar, and Martian systems as well as spacecraft. The virtual International Space Station (ISS) model developed by JAXA was adopted as the representative of spacecraft in the PHITS simulation. This paper focuses on the comprehensive discussions on the difference of cosmic-ray environments and the effective methods of their shielding in various exposure situations.
Kataoka, Ryuho*; Sato, Tatsuhiko; Miyake, Shoko*; Shiota, Daiko*; Kubo, Yuki*
Space Weather, 16(7), p.917 - 923, 2018/07
Times Cited Count:19 Percentile:69.84(Astronomy & Astrophysics)A ground level enhancement (GLE) event occurred on 10-11 September 2017, associated with X8.2 solar flare exploded at western limb. The magnitude of the GLE was not so large even at the peak, but the duration of the event was longer than average. We briefly report the results of our manually conducted nowcast using WASAVIES (Warning System of AViation Exposure to Solar energetic particles). The maximum radiation dose rate at 12 km flight altitude was estimated to be approximately 2 Sv/h, which is only one-third of the corresponding background dose rate due to the galactic cosmic-ray exposure. This result verified the safety of aircrews and passengers in aviation during this event.
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:19 Percentile:69.84(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.
Miyake, Shoko*; Kataoka, Ryuho*; Sato, Tatsuhiko
Space Weather, 15(4), p.589 - 605, 2017/04
Times Cited Count:19 Percentile:64.02(Astronomy & Astrophysics)Weak solar activity and high cosmic-ray flux during the coming solar cycle are qualitatively anticipated by the recent observation that show the decline in the solar activity levels. We have quantitatively predicted the cosmic-ray modulation and resultant radiation exposure at flight altitude by using the time-dependent and three dimensional model of the cosmic-ray modulation. The database of airshower simulation performed by Particle and Heavy Ion Transport code System, PHITS, was employed in the prediction. Our predictions of the neutron monitor counting rate and the radiation dose of aircrews during the solar cycle 24/25 have some natures caused by the charge sign dependence of the cosmic-ray modulation, such as the flat-top profiles.
Kawamura, Hideki*; Noda, Masaru*; Nishikawa Naohito*; Sato, Shoko*; Tanaka, Tatsuya*
JNC TJ7410 2003-002, 515 Pages, 2003/03
Tono Geoscience Center (TGC) of Japan Nuclear Cycle Development Institute has been conducting the Regional Groundwater Investigation and Mizunami Underground Laboratory (MIU) Project in order to develop investigation technologies and evaluation methods of geological environment. At present, towards the next progeress reporting on research and development for geological disposal of HLW in Japan, based on the existing research and development results, the Projects which are conducted at Tono Geoscience Center are required for promoting the MIU program smoothly and effeciently with regard to the current Japanese HLW program. According to such situation, for planning of the geological environment investigation and research at TGC and the next progress reporting, this study has investigated and summarizes overseas environmental impact assessments for final disposal, overseas site characterization and site selection, and overseas research plan of underground research laboratories. Based on the results of investigation, some technologies which have possibility to be applied to the MIU Project have been studied. Also overseas quality assurance programs have been investigated, and examples of the application of their concepts to MIU project have been considered.
Iwata, Yoshihiro*; Takahashi, Shoko*; Ishii, Keizo*; Sato, Takahiro; Kamiya, Tomihiro
no journal, ,
no abstracts in English
Sato, Tatsuhiko; Nagamatsu, Aiko*; Ueno, Haruka*; Kataoka, Ryuho*; Miyake, Shoko*; Takeda, Kazuo*; Niita, Koji*
no journal, ,
We are developing the computational dosimetry system used for cosmic-ray exposure, based on the Particle and Heavy Ion Transport code System PHITS. In the system, cosmic-ray environments outside spacecraft are estimated from the JAXA's space-radiation environment model, while cosmic-ray environments inside spacecraft are determined from the PHITS simulation. The details of the system will be presented at the meeting.
Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Kubo, Yuki*; Ishii, Mamoru*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
Estimation of radiation doses for astronauts as well as aircrews due to the exposure to solar energetic particles (SEP) is one of the greatest challenges in space weather research. We are therefore developing a WArning System for AVIation Exposure to Solar energetic particle (WASAVIES), under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP). In the system, the SEP fluxes incident to the atmosphere are calculated by physics-based models. Thus, WASAVIES can estimate not only the current value but also time variation of the aircrew doses after a GLE event occurs. A brief outline of WASAVIES together with the status of on-going research subjects such as development of the automatic calculation algorithm will be presented at the meeting.
Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Kubo, Yuki*; Ishii, Mamoru*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
Estimation of radiation doses for astronauts as well as aircrews due to the exposure to solar energetic particles (SEP) is one of the greatest challenges in space weather research. We are therefore developing a WArning System for AVIation Exposure to Solar energetic particle (WASAVIES), under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP). In the system, the radiation doses due to SEP exposure at flight altitudes are calculated on the basis of physics-based models and databases with four free parameters, which express the absolute value, power index, and time profiles of SEP fluxes near the sun, and the pitch angle incident to the magnetosphere. Thus, WASAVIES can estimate not only the current value but also time variation of the aircrew doses after a GLE event occurs. A brief outline of WASAVIES together with the status of on-going research subjects such as development of the web-based nowcast and forecast system will be presented at the meeting.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Tsujino, Takashi*
no journal, ,
A ground level enhancement (GLE) event occurred on 10-11 September 2017, associated with X8.2 solar flare exploded at western limb. The magnitude of the GLE was not so large even at the peak, but the duration of the event was longer than average. We briefly report the results of our manually conducted nowcast using WASAVIES (Warning System of AViation Exposure to Solar energetic particles). The maximum radiation dose rate at 12 km flight altitude was estimated to be approximately 2 Sv/h, which is only one-third of the corresponding background dose rate due to the galactic cosmic-ray exposure. This result verified the safety of aircrews and passengers in aviation during this event. The automatic calculation system of WASAVIES was developed, and it will be released via website of Regional Warning Center Japan, International Space Environment Services (RWC Japan, ISES) at NICT in near future.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
A physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, is developed for nowcasts and forecasts the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. A web-interface of WASAVIES is also developed and will be released in the near future through the public server of NICT.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
We are developing a physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, under the framework of the PSTEP project in Japan. It can nowcast and forecast the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. A web-interface of WASAVIES is also developed and will be released in the near future through the public server of NICT.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*; Ueno, Haruka*; et al.
no journal, ,
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 detailed calculation procedures of WASAVIES-EO will be presented at the meeting, together with the results of its validation based on the experimental data measured in ISS during GLE60, 71 and 72.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Miyoshi, Yoshizumi*
no journal, ,
We are developing a physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, under the framework of the PSTEP project in Japan. It can nowcast and forecast the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. In this presentation, we will explain details of the web-interface of WASAVIES, which will be released in the near future through the public server of NICT.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
no journal, ,
We are developing a physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, under the framework of the PSTEP project in Japan. It can nowcast and forecast the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. A web-interface of WASAVIES is also developed and will be released from March 2019 through the public server of NICT.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Miyoshi, Yoshizumi*
no journal, ,
We are developing a physics-based warning system for aviation exposure to solar energetic particles, WASAVIES, under the framework of the PSTEP project in Japan. It can nowcast and forecast the radiation dose rates all over the world up to 24 h after the large solar flare onset. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. The accuracy of the calculated dose rates is well validated by the reproducibility of the count rates of several neutron monitors and GOES proton fluxes. A web-interface of WASAVIES was also developed and released via the public server of NICT.