Observation of solar neutrons at high altitudes near the equator

本研究旨在通过地面观测加速质子与太阳大气相互作用产生的高能太阳中子（>100MeV），阐明太阳表面高能粒子的加速机制。在研究太阳加速时，使用中子比质子更可取，因为中子不会被行星际磁场反射。为了有效地探测太阳中子，以名古屋大学日地环境实验室为主体的小组在世界范围内完成了一个太阳中子探测器网络，对太阳进行全天观测。这些探测器位于赤道附近的高山上，因为太阳中子在空气中传播时会衰减。根据科学研究补助金，玻利维亚的Chacaltaya太阳中子探测器的数据采集系统是15年前设计的，已经被一个相当新的系统所取代， ...更多信息 其中数据获取在电力的断电之后自动开始。查卡尔塔亚（海拔：5250米，纬度：16度S）是我们网络中观测太阳中子的最佳地点。这一经验对在墨西哥Sierra Negra的探测器采用相同的系统很有用，因为那里没有人长期停留。Sierra Negra（海拔4600米，北纬19度）是观测太阳中子的第二好地方。据信这些新系统将在2007年开始的下一个太阳周期中正常工作，并且我们可以比以前更有效地检测太阳中子。当我们正在改进这两个系统时，2005年9月7日发生了一次大规模的太阳耀斑。在查卡尔塔亚和Sierra Negra的太阳中子探测器都成功地探测到了太阳中子信号，这是我们的探测器迄今为止获得的最重要的信号。此外，查卡尔塔亚和墨西哥城的中子监测器也探测到了清晰的信号。对这一事件的分析目前还在进行中，而获得这类事件正是我们此次科研资助的目的所在。少

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taking system of the solar neutron detector at Chacaltaya in Bolivia, which was designed more than 15 years ago, has been replaced by a quite a new system, by wh … More ich a data taking starts automatically after a power cut of the electricity.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