The research group led by Professor Shoji Torii of the Waseda University Faculty of Science and Technology is using the observation data of the "High Energy Electron and Gamma Ray Observatory (CALET)" installed at the International Space Station (ISS) to make the ISS magnetic latitude from evening to night *. It was revealed that there was a "concentrated heavy rain of electrons" in which a large amount of radioactive electrons (electrons with an energy of about 100 million electron volts) were poured over several minutes when passing through a high area.
"CALET" is an observation device carried to the ISS in August 2015, and is a joint research project between JAXA and Waseda University.The research team includes 8 research institutes such as the National Institute of Polar Research and the University of Tokyo Institute for Cosmic Ray Research.
By observing extremely high-energy electrons, gamma rays, protons and nuclear components flying in the universe with high accuracy by "CALET", "the origin and acceleration mechanism of high-energy cosmic rays and gamma rays" and "cosmic rays are galaxies". The purpose is to elucidate the mechanism that is transmitted inside.
As a result of analyzing the data for 4 months from the start of CALET observation, the phenomenon of "concentrated electron rain" occurs repeatedly at the timing when the ISS passes through the area with high magnetic latitude from the evening to the middle of the night. It is also clear that it occurs mainly when the Van Allen belt (the region where radiation electrons are concentrated from 1 km to 4 km above the equator) is abundant and when aurora activity is active. Became.
Since "burst of electrons" causes damage due to charging of artificial satellites and ozone destruction in the middle atmosphere, it is expected that it will be useful for research on space weather forecasts and atmospheric chemistry.The results of this research are posted online in Geophysical Research Letters (May 2016, 5).
* Magnetic latitude is the latitude determined based on the axis of the earth's geomagnetism.
