Study on galactic cosmic-ray transport in outer heliosphere

对MHD模型日球层中宇宙线轨道的计算表明，几乎所有能量在500GeV左右的粒子都是从日尾到达地球的，它们的轨道在太阳风终止激波和日球层顶之间形成的磁壁处发生了明显的偏转。我们还分析了西藏高计数空气簇射（AS）实验观测到的10TeV宇宙线强度的恒星日变化，证实了在10TeV区域不存在“尾入”分量各向异性，并且在1TeV以上，随着能量的增加，“尾入”分量各向异性逐渐减小。在西藏观测到的日变化与在喜马拉雅山AS实验的结果相当一致。Norikura超过15年，两者都符合“损失锥”分量各向异性。在“损失锥”各向异性中没有看到显著的能量依赖性。西藏AS实验还记录到恒星日变幅度有明显的季节变化。这种季节性变化可能是由于地球自转引起的，表明大尺度太阳磁场对宇宙线轨道的影响。为了研制新的宇宙线μ子探测器，我们采用四层88个正比计数器构建了窄角多方向望远镜，并对其性能进行了评价。一个新的记录系统，其中一台计算机确定每个μ子事件的入射方向，被证实是足够有用的，我们的网络观测。我们也一直在收集系统性能稳定性的数据，通过在巴西的Sao Martinho安装一个原型多向μ子探测器，我们扩大了现有网络的纵向覆盖范围。在巴西的新的探测器网络覆盖了初级宇宙射线的整个俯仰角，目前正在观测地磁暴的前兆。

Calculations of cosmic-ray orbits in a MHD model heliosphere showed that almost all particles with energy around 500GeV are arriving at the earth from the heliotail with their orbits significantly deflected at the magnetic wall formed in the region between the solar wind termination shock and heliopause. We also analyzed the sidereal daily variation of 10TeV cosmic-ray intensity observed by a high-count air shower ( AS ) experiment at Tibet and confirmed that the "Tail-in" component anisotropy doesn't exist in 10TeV region and diminishes with, increasing energy above 1TeV. The daily variation observed at Tibet was quite consistent with the result by the AS experiment at Mt. Norikura over 15 years, both were consistent with the "Loss-cone" component anisotropy. There was no significant energy dependence seen in the "Loss-cone" anisotropy. Tibet AS experiment also recorded a significant seasonal change in the magnitude of sidereal daily variation. This seasonal change, possibly due to earth's revolution suggests a influence of large scale solar magnetic field on cosmic-ray orbits.Aiming to develop a new cosmic-ray muon detector, we constructed a narrow angle multidirectional telescope using 88 proportional counters in four layers and evaluated the performance. A new recording system, in which a computer determines the incident direction of every muon event, is confirmed to be enough useful for our network observation. We have also been collecting data of the stability of the system performance.By installing a prototype multidirectional muon detector at Sao Martinho in Brazil, we extended the longitudinal coverage of the present network. The new network with the detector in Brazil, which covers a full range of pitch angle of primary cosmic-rays, is now observing precursors of geomagnetic storms.