Origin of Anomalous Cosmic Rays and the Acceleration Mechanism

我们在1992年9月至1994年8月期间，利用轨道高度为1 Au的GEOTAIL卫星上的MI-1/2和HI粒子望远镜测量了宇宙线粒子，观测了能量为3-250 MeV/n的He到Fe的安静时粒子。在1992年末，太阳活动极大期之后，观测到了低于50 MeV/n的能谱中O、N和Ne的异常增强。异常C也很明显，尽管C增强与它们相比很小。在最近两个太阳活动周，宇宙线异常数据与中子监测数据之间的相关性较好，但在1992-1994年，宇宙线异常数据与中子计数率之间的相关性较大。在这个太阳活动周中，O、N和Ne的通量已迅速恢复到前一个太阳活动极小期的水平，尽管ACR通量迅速恢复的原因目前还不清楚，但在太阳活动极小期到来之前的第22周，宇宙线N、O和Ne的异常强存在已被证实。异常Ar是VOYAGER在深空观测到的，但在1 Au处首次观测到。我们发现了第一个证据，表明在30 MeV/n以下的异常宇宙射线中出现了可测量的硫成分。与具有高第一电离势（FIPs）的异常N、O和Ne通量相比，具有中等FIPs的异常C和S通量非常小。这些结果可以从菲斯克等人（1974）提出的异常宇宙射线起源的设想中定性地预期。这意味着它们在非常局部的星际介质中被显著电离。

We have measured cosmic ray particles during the period September 1992 through August 1994 using the particle telescopes MI-1/2 and HI onboard the GEOTAIL satellite orbiting at 1 AU.We have examined the quiet-time particles from He to Fe with the energies of 3-250 MeV/n. Remaekable enhancement of anomalous O,N and Ne in the energy spectra below 50 MeV/n was observed in the late 1992, just after the solar maximum. The anomalous Cis also evident though the C enhancement is small compared with them. The correlation between the anomalous cosmic ray data and the neutron monitor data is relatively good in the last two solar cycles but in the years 1992-1994 there is a large difference between the ACR and the neutron counting rate. The fluxes of O,N and Ne in this solar cycle have rapidly recovered to the level in the previous solar minimum although the origin of this rapid recovery of the ACR fluxes is presently unknown.Strong presence of anomalous cosmic ray N,O and Ne was shown well before the approaching solar minimum at solar cycle 22. Anomalous Ar was firstly observed at 1 AU though it was observed by the VOYAGER in deep space. We found the first evidence for the emergence of a measurable sulfur component of anomalous cosmic rays below 30 MeV/n. Comparing the fluxes of anomalous N,O and Ne with high first ionization potentials (FIPs) , the anomalous C and S fluxes, which have intermediate FIPs, are very small. These results could be qualitatively expected from the scenario for the origin of the anomalous cosmic rays proposed by Fisk et al. (1974) . It implies that they are significantly ionized in the very local interstellar medium.