| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
This research aims to clarify the acceleration mechanism of high energy particles at the solar surface, by observing on the ground high energy solar neutrons (>100MeV) produced by the interaction between accelerated protons and the solar atmosphere. It is more preferable to use neutrons than protons to study solar acceleration, because neutrons are not reflected by the interplanetary magnetic field. In order to detect solar neutrons effectively, the group which mainly includes Solar-Terrestrial Environment Laboratory, Nagoya University, has completed a network of solar neutron detectors in the world to observe the Sun for a whole day. These detectors are located at high mountains near the equator, because solar neutrons are attenuated while propagating in the air. According to the Grant-in-Aid for Scientific Research, the data taking system of the solar neutron detector at Chacaltaya in Bolivia, which was designed more than 15 years ago, has been replaced by a quite a new system, by wh
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ich a data taking starts automatically after a power cut of the electricity. Chacaltaya (altitude : 5250m, latitude : 16 degrees S) is the best place to observe solar neutrons in our network. This experience was useful to adopt the same system to the detector at Sierra Negra in Mexico, where nobody stays permanently. Sierra Negra (altitude : 4600m, latitude : 19 degrees N) the second best place to observe solar neutrons. These new systems are believed to work properly during the next solar cycle, which will start in 2007, and, we bacame to detect solar neutrons much more efficiently than before. While we were improving both systems, a large solar flare occurred on September 7, 2005. The solar neutron detectors both at Chacaltaya and Sierra Negra have succeeded in detecting solar neutron signals, which are the most significant ones so far obtained by our detectors. Moreover, neutron monitors at Chacaltaya and Mexico City also detected clear signals. The analysis on this events is now in progress, but obtaing this kind of event is what we have aimed by this Grant-in-Aid for Scientific Research. Less
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