标题： 2006年12月Forbush事件恢复时间的能量和电荷符号依赖性的证据，由PAMELA实验测量 显示英文标题

标题： Evidence of energy and charge sign dependence of the recovery time for the December 2006 Forbush event measured by the PAMELA experiment

摘要： 新的关于2006年12月由PAMELA仪器测量的短期银河宇宙射线（GCR）强度变化（Forbush减少）的最新结果被提出。Forbush减少是与行星际瞬变现象如激波和行星际日冕物质抛射（ICMEs）相关的银河宇宙射线强度的突然抑制。过去对此现象的大部分测量都是通过地面探测器如中子监测器或μ子望远镜进行的。这些技术只能对整个能量范围内的总体银河宇宙射线强度进行间接检测。由于PAMELA磁谱仪的独特特性，首次在广泛的刚度范围（0.4 - 20 GV）内以及对于不同种类的银河宇宙射线直接在太空中进行了研究，该Forbush减少始于2006年12月14日，是在2006年12月13日太阳发生日冕物质抛射之后发生的。使用每日平均的银河宇宙射线质子强度来研究Forbush减少的振幅和恢复时间的刚度依赖性。此外，首次研究了Forbush减少期间氦和电子强度的时间变化。有趣的是，在Forbush减少期间，氦和质子强度的时间演化结果一致，而低刚度电子（< 2 GV）显示出更快的恢复。电子恢复的差异被解释为银河宇宙射线在太阳系中传播过程中经历的漂移运动引入的电荷符号依赖性。 显示英文摘要

摘要： New results on the short-term galactic cosmic ray (GCR) intensity variation (Forbush decrease) in December 2006 measured by the PAMELA instrument are presented. Forbush decreases are sudden suppressions of the GCR intensities which are associated with the passage of interplanetary transients such as shocks and interplanetary coronal mass ejections (ICMEs). Most of the past measurements of this phenomenon were carried out with ground-based detectors such as neutron monitors or muon telescopes. These techniques allow only the indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease commencing on 2006 December 14, following a CME at the Sun on 2006 December 13 was studied in a wide rigidity range (0.4 - 20 GV) and for different species of GCRs detected directly in space. The daily averaged GCR proton intensity was used to investigate the rigidity dependence of the amplitude and the recovery time of the Forbush decrease. Additionally, for the first time, the temporal variations in the helium and electron intensities during a Forbush decrease were studied. Interestingly, the temporal evolutions of the helium and proton intensities during the Forbush decrease were found in good agreement, while the low rigidity electrons (< 2 GV) displayed a faster recovery. This difference in the electron recovery is interpreted as a charge-sign dependence introduced by drift motions experienced by the GCRs during their propagation through the heliosphere.