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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:5 Percentile:42.72(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

Comparison of cosmic-ray environments on earth, moon, mars and in spacecraft using PHITS

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:11 Percentile:84.19(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.

Journal Articles

Space radiation dosimetry to evaluate the effect of polyethylene shielding in the Russian segment of the International Space Station

Nagamatsu, Aiko*; Casolino, M.*; Larsson, O.*; Ito, Tsuyoshi*; Yasuda, Nakahiro*; Kitajo, Keiichi*; Shimada, Ken*; Takeda, Kazuo*; Tsuda, Shuichi; Sato, Tatsuhiko

Physics Procedia, 80, p.25 - 35, 2015/12

 Times Cited Count:6 Percentile:90.08

JAXA has been investigated the effect of the shielding material for dosimeters in the ISS Russian segment under the ALTCRISS project. The PADLES package is a passive dosimeters which usually consists of two types of passive and integrating dosimeters, a CR-39 plastic nuclear track detector and a thermoluminescence dosimeter. In the ALTCRISS experiments, both tissue-equivalent material CR-39 PNTDs and NAN-JAERI were enclosed in the PADLES packages as radiators for CR-39 to precisely measure a personal exposed doses. We compared the doses obtained by PADLESs with or without the PEs, and with or difference of the two tissue-equivalent materials. The results of space radiation measurements of the ALTCRISS project Phase 1 to 4 using the PADLES system will be reported in this time: Phase 1 experiments was from December 2005 to April 2006, Phase 2 was from April to September 2006, phase 3 was from Sep 2006 to April 2007, and Phase 4 was conducted from May to October 2007.

Oral presentation

Tanpopo Working Group report; Space exposure of microbes and organic materials

Yokobori, Shinichi*; Kobayashi, Kensei*; Mita, Hajime*; Yabuta, Hikaru*; Nakagawa, Kazumichi*; Narumi, Issei; Hayashi, Nobuhiro*; Tomita, Kaori*; Kawaguchi, Yuko*; Shimizu, Yasuyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Astronaut dose estimation using the PHITS code in combination with realistic models of the Kibo module and the MATROSHKA phantom

Sato, Tatsuhiko; Nagamatsu, Aiko*; Takeda, Kazuo*; Niita, Koji*; Puchalska, M.*; Sihver, L.*; Reitz, G.*

no journal, , 

Estimation of organ doses and their mean quality factors for astronauts due to cosmic-ray exposure has been an essential issue in the planning of long-term space missions. We therefore performed simulation for calculating the organ doses and their mean quality factors inside the MATROSHKA phantom, using a realistic geometry of the Kibo module in combination with the NUNDO phantom, which was constructed based on the CT image of the phantom. The particle and heavy ion transport code system PHITS was employed in the simulation. From preliminary results, it is found that the calculated organ doses and their mean quality factors inside the MATROSHKA phantom agree with the corresponding experimental data fairly well.

Oral presentation

Estimation of astronaut dose inside the Kibo module during large solar flare events

Sato, Tatsuhiko; Kataoka, Ryuho*; Nagamatsu, Aiko*

no journal, , 

Forecast 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. In last 3 years, we have developed a warning system of aviation exposure to solar energetic particles: WASAVIES, which can predict the SEP doses at any flight conditions within 2.5 hours after the onset of ground level enhancements (GLE). In this system, the SEP fluxes incident to the atmosphere are calculated by physics based models, and they are converted to radiation doses using a database developed on the basis of air-shower simulation. In this study, we applied the same physics-based models to the estimate of the SEP fluxes on the orbit of International Space Station, and converted the fluxes to radiation doses for astronauts staying inside the Kibo module.

Oral presentation

Space radiation dosimetry in Kibo module, 2; Simulation

Sato, Tatsuhiko; Nagamatsu, Aiko*; Takeda, Kazuo*; Niita, Koji*; Puchalska, M.*; Sihver, L.*

no journal, , 

Estimation of doses for astronauts due to space radiation exposure has been an essential issue in the planning of long-term space missions. For that purpose, we developed a simulation tool for estimating radiation environments as well as doses for astronauts stayed in the Kibo module in ISS. The tool consists of the Particle and Heavy Ion Transport Simulation code, PHITS, in combination with the virtual Kibo module developed by JAXA. The accuracy of the simulation was examined on the basis of the experimental data obtained from the Area PADLES and MATROSHKA-Kibo measurements. It was found from the examination that the calculated doses agree with the measured data fairly well. The results of the examination also suggested that the consideration of the east-west asymmetry is important to reproduce the location-dependence of doses inside the Kibo module.

Oral presentation

Space radiation dosimetry in Kibo module, 1; Measurement

Nagamatsu, Aiko*; Sato, Tatsuhiko; Kitajo, Keiichi*; Shimada, Ken*; Sakane, Sayuri*; Takeda, Kazuo*; Niita, Koji*

no journal, , 

Continuous space-radiation dosimetry is one of the key missions at the International Space Station (ISS) for radiation health management of crew members and for scientific activities. Since the Japanese Experiment Module KIBO was attached to the ISS in 2008, we have been performing continuous space radiation dosimetry using a passive and integrating dosimeters, PADLES (Passive Dosimeter for Life-Science Experiments in Space). To date, several hundreds of PALDES having returned from the ISS showed anisotropy of the radiation environment and changes in the dose rate due to ISS attitudes and differences in shielding conditions. On this occasion, an overview of JAXA's continuous radiation dosimetry activities and the preliminary results will be presented with the discussions, which based on the simulation analysis with Particle and Heavy Ion Transport code System PHITS.

Oral presentation

Space and terrestrial cosmic-ray environments estimated using PHITS and EXPACS

Sato, Tatsuhiko; Abe, Shinichiro; Nagamatsu, Aiko*

no journal, , 

Evaluation of cosmic-ray environment is essential in the estimate of soft error rates (SER) of semiconductor devices used not only in spacecraft but also on the Earth. This paper briefly summarizes the features of our developed models for calculating space and terrestrial cosmic-ray fluxes, which are based on the Particle and Heavy Ion Transport code System (PHITS) and EXcel based Program for calculating Atmospheric Cosmic-ray Spectrum (EXPACS), respectively. Examples of the calculated SERs obtained using EXPACS are also presented, in comparison with the corresponding data obtained using the standard model described in JESD89A. The difference between the calculated SERS is probably attributable to the inaccuracy associated with the simple scaling method adopted in the JESD89A model.

Oral presentation

Simulation of the radiation environment inside ISS using the PHITS code

Sato, Tatsuhiko; Nagamatsu, Aiko*; Takeda, Kazuo*; Niita, Koji*; Puchalska, M.*; Sihver, L.*

no journal, , 

Estimation of doses for astronauts due to space radiation exposure has been an essential issue in the planning of long-term space missions. For that purpose, we developed a simulation tool for estimating radiation environments as well as doses for astronauts stayed in the Kibo module in ISS. The tool consists of the Particle and Heavy Ion Transport Simulation code, PHITS, in combination with the virtual Kibo module developed by JAXA. The accuracy of the simulation was examined on the basis of the experimental data obtained from the Area PADLES and MATROSHKA-Kibo measurements. It was found from the examination that the calculated doses agree with the measured data fairly well. The results of the examination also suggested that the considerations of the east-west asymmetry and the existence of other modules are important to reproduce the location-dependence of doses inside the Kibo module.

Oral presentation

Radiation protection of humans in space and aviation; Current states and future needs on the warning system for aviation exposure to SEP (WASAVIES)

Sato, Tatsuhiko; Ishii, Mamoru*; Kataoka, Ryuho*; Kubo, Yuki*; Minoshima, Takashi*; Miyoshi, Yoshizumi*; Nagamatsu, Aiko*; Shiota, Daiko*; Takashima, Takeshi*; Yasuda, Hiroshi*

no journal, , 

Forecast 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. In last 5 years, we have developed a WArning System for AVIation Exposure to Solar energetic particles: WASAVIES. In this system, the SEP fluxes incident to the atmosphere are calculated by physics-based models, and they are converted to radiation doses using a database developed on the basis of air-shower simulation. However, it takes approximately 2.5 hours to determine the parameters used in the physics-based models after the detection of GLEs, and thus, the current WASAVIES cannot predict doses during the peak of GLEs. Therefore, we are trying to reduce the time for evaluating the parameters, as well as to develop a nowcast system for the radiation dose due to SEP exposure, under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP) in Japan. A brief outline of WASAVIES together with our future strategy will be presented at the meeting.

Oral presentation

Cosmic-ray dosimetry based on the PHITS code

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.

Oral presentation

Real-time estimation of astronaut doses during large solar particle events based on WASAVIES

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.

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